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THE 
LONDON,  EDINBURGH,  and  DUBLIN 

PHILOSOPHICAL    MAGAZINE 

AND 

JOURNAL   OF    SCIENCE. 

CONDUCTED  BY 

SIR  DAVID  BREWSTER,  K.H.  LL.D.  F.R.S.L.&E.  &c. 
RICHARD  TAYLOR,  F.L.S.  G.S.  Astr.S.  Nat.H.Mosc.  &c 
RICHARD  PHILLIPS,  F.R.S.L.&E.  F.G.S.  &c 
ROBERT  KANE,  M.D.  M.R.I.A. 


"  Nee  aranearum  sane  textus  ideo  melior  quia  ex  se  fila  gignunt,  nee  noster 
vilior  quia  ex  alienis  libamus  ut  apes."    Just.  Lips.  Polit.  lib.  i.  cap.  1 .  Not. 


VOL.   XXI. 

NEW  AND  UNITED  SERIES  OF  THE  PHILOSOPHICAL  MAGAZINE, 
ANNALS  OF  PHILOSOPHY,  AND  JOURNAL  OF  SCIENCE. 

JULY— DECEMBER,  1842. 


LONDON: 

RICHARD  AND  JOHN  B.  TAYLOR,  RED  LION  COURT,  FLEET  STREET, 

Printers  and  Publishers  to  the  University  of  London; 

SOLD    BY    LONGMAN,    BROWN,    GREEN,   AND  LONGMANS ;     CADELL;    SIMPKIN, 
MARSHALL    AND    CO.;     S.     HIGHLEY  ;      WHITTAKER    AND    CO.;     AND 

SHERWOOD,  GILBERT,  AND   PIPER,    LONDON  :    BY    ADAM    AND 

CHARLES  BLACK,  AND  THOMAS  CLARK,  EDINBURGH;    SMITH 

AND    SON,    GLASGOW  ;    HODGES    AND    SMITH,    DUBLIN  : 

AND  G.  W.  M.  REYNOLDS,  PARIS. 


The  Conductors  of  the  Philosophical  Magazine  have  to  acknowledge  the  editorial 
assistance  rendered  them  hy  their  friend  Mr.  Edward  W.  Brayley,  F.L.S., 
F.G.S.,  Assoc.  Inst.  C.  E. ;  Member  of  the  American  Philosophical  Society, 
and  Corresponding  Member  of  the  Philosophical  Society  of  Basle,  &c.  Librarian 
to  the  London  Institution- 


CONTENTS  OF  VOL.  XXI. 


NUMBER  CXXXV.— JULY,  1842. 

Page 

Prof.  D.  P.  Gardner  on  the  Influence  of  the  Dew-point  on  Ve- 
getables, considered  especially  with  reference  to  their  Tem- 
perature          1 

Messrs.  W.  Francis  and  H.  Croft's  Notices  of  the  Results  of 

the  Labours  of  Continental  Chemists  (continued) 15 

Mr.  Galloway's  Further  Remarks  on  Fernel's  Measure  of  a 
Degree,  in  Reply  to  Professor  De  Morgan's  Letter  in  the 

Number  for  May    22 

The  Rev.  D.  Williams's  Supplementary  Notes  on  the  true  Posi- 
tion in  the  "  Devonian  System  "  of  the  Cornish  Killas  ....       25 

The  Rev.  P.  Kelland's  Note  on  Fluid  Motion 29 

Prof.  Dove's  Experiments  in  Magneto -Electricity,   illustrative 

of  a  Passage  in  Professor  Faraday's  Researches    33 

Dr.  R.  Kane's  Note  on  the  Composition  of  the  Basic  Sulphate 

of  Mercury,  or  Turpeth  Mineral 35 

Mr.  T.  S.  Davies  on  Pascal's  Mystic  Hexagram 37 

Mr.  W.  H.  Balmain's  New  Process  for  Preparing  Oxygen. ...      42 
Mr.  S.  M.  Drach  on  Sir  D.  Brewster's  Deductions  from  the 

Hourly  Observations  at  Leith  in  1824-25     43 

Mr.  Earnshaw  on  the  Motion  of  Luminous  Waves  in  an  Elastic 
Medium,  consisting  of  a  system  of  detached  particles,  sepa- 
rated by  finite  intervals 46 

Proceedings  of  the  Royal  Society    50 

1» Royal  Astronomical  Society 56 

London  Electrical  Society 61 

Royal  Irish  Academy    64 

New  Books  : — Howard's  Cycle  of  Eighteen  Years  in  the  Seasons 

of  Britain    69 

On  the  Red  Molybdate  of  Lead,  by  If.  G.  Rose 73 

Method  of  distinguishing  between  weak  Solutions  of  Nitrates 

and  Chlorates,  by  M.  Vogel,  jun 74 

On  the  Existence  of  Sulphur  in  Plants 74 

Action  of  Salts  on  Living  Plants 76 

On  Chlorite  and  Repidolite,  by  M.  Kobell 76 

Analysis  of  theTachylyte  of  Vogelsgebirge,  by  M.  Klett     ....      77 

Analysis  of  Native  Aluminates 78 

Meteorological  Observations  for  May  1842 79 

Meteorological  Observations  made  at  the  Apartments  of  the 
Royal  Society  by  the  Assistant  Secretary,  Mr.  Roberton ; 
by  Mr.  Thompson  at  the  Garden  of  the  Horticultural  Society 
at  Chiswick,  near  London;  by  Mr.  Veall  at  Boston;  by  the 
Rev.  W.  Dunbar  at  Applegarth  Manse,  Dumfries-shire ;  and 
by  the  Rev.  C.  Clouston  at  Sandwick  Manse,  Orkney     ....      80 

a  2 


IV  CONTENTS  OF  VOL.  XXI. 

Page 

NUMBER  CXXXVL— AUGUST. 

M.  Hess  on  the  Scientific  Labours  of  Jeremias  Benjamin  Richter. 
Addressed  to  the  Imperial  Academy  of  Sciences  of  St.  Peters- 
burg, at  the  public  sitting  of  Dec.  29,  1840 81 

Mr.  J.  R.Christie  on  the  Extension  of  Budan's   Criterion  for 
the  Imaginary  Roots,  and  a  new  Method  of  effecting  the  Se- 
paration of  the  nearly  equal  Roots  of  a  numerical  Equation      96 
The  Rev.  Prof.  Challis  on  the  Analytical  Condition  of  the  Rec- 
tilinear Motion  of  Fluids    101 

Mr.  Gulliver's  Contributions  to  the  Minute  Anatomy  of  Ani- 

.mals.     No.  II 107 

Mr.  Baily's  Account  of  some  Experiments  with  the  Torsion-rod, 

for  determining  the  Mean  Density  of  the  Earth    Ill 

Prof.  Powell's  Note  on  Mr.  Earnshaw's  Paper  in  Phil.  Mag.  for 

April  1842 122 

The  Rev.  P.  Kelland's   Reply  to  some  Objections  against  the 

Theory  of  Molecular  Action  according  to  Newton's  Law    . .     124 
Mr.  C.  Hood  on  some  peculiar  Changes  in  the  Internal  Struc- 
ture of  Iron,  independent  of,  and  subsequent  to,  the  several 

Processes  of  its  Manufacture »  . .    130 

The  Rev.  Humphrey  Lloyd's  Notice  of  a  remarkable  Magnetic 
Disturbance  which  occurred  on  the  2nd  and  4th  of  July,  1842   137 

Proceedings  of  the  Geological  Society 141 

American  Philosophical  Society 150 

Fourth  Meeting  of  the  Italian  Congress  of  Men  of  Science.  ...    153 
On  the  Earthquake  felt  in  parts  of  Cornwall,  on  February  17, 

1842 153 

On  the  Blue  Colour  of  Ultramarine,  by  M.  Eisner 156 

Preparation  of  Oxichloric  Acid,  by  M.  Ad.  Nativelle 157 

On  the  Action  of  Water  on  Lead,  by  Prof.  Christison     158 

Apothecaries'  Hall  :  appointment  of  Mr.  Warington    159 

Meteorological  Observations  for  June  1842     159 

Table 160 


NUMBER  CXXXVIL— SEPTEMBER. 

Mr.  W.  Francis's  Chemical  Examination  of  the  Fruit  of  Meni- 

spermum  Cocculus  (Semina  Cocculi  Indici)    161 

Mr.  Gulliver's  Contributions  to  the  Minute  Anatomy  of  Ani- 
mals.    No.  Ill 168 

Mr.  F.  C.  Calvert  on  the  Preparation  of  Quina  and  Cinchonia     171 

Prof.  J.  Booth  on  a  Theorem  in  Analytic  Geometry 176 

Mr.  Darwin's  Notes  on  the  Effects  produced  by  the  Ancient 
Glaciers  of  Caernarvonshire,  and  on  the  Boulders  transported 

by  Floating  Ice 180 

Mr.  J.  Rees's  Application  t  i  particular  instances  of  the  general 
Formula  for  eliminating  the  Weights  of  Mixed  Bases 188 


CONTENTS  OF  VOL.  XXI.  V 

Page 
Mr.  T.  S.  Davies  on  the  Employment  of  Polar  Coordinates  in 

expressing  the  Equation  of  the  Straight  Line,  and  its  appli- 
cation to  the  proof  of  a  property  of  the  Parabola 190 

Mr.  R.  Warington  on  the  Change  of  Colour  in  the  Biniodide 

of  Mercury 192 

Mr.  H.  Croft  on  a  new  Oxalate  of  Chromium  and  Potash  ....  197 
Mr.  R.  "Warington's  additional  Observations  on  the  Red  Oxalate 

of  Chromium  and  Potash 201 

The  Rev.  P.  Kelland's  Reply  to  some  Objections  against  the 

Theory  of  Molecular  Action  according  to  Newton's  Law  .  .  202 
Sir  D.  Brewster  on  the  Connexion  between  the  Phenomena  of 

the  Absorption  of  Light  and  the  Colours  of  thin  Plates  ....  208 
Mr.  Earnshaw  on  the  Theory  of  the  Dispersion  of  Light ;   in 

reply  to  Prof.  Powell's  Note 217 

Mr.  H.  A.  Goodwin's  Proof  of  Professor  Wallace's  Property  of 

the  Parabola 219 

Proceedings  of  the  Royal  Society 220 

Royal  Irish  Academy 228 

On  Curcumine,  by  M.  Vogel,  jun 233 

On  the  Action  of  Acids  on  Curcumine,  by  M.  Vogel,  jun 234 

On  the  Action  of  Alkaline  Substances  on  Curcumine 235 

Insoluble  Salts  of  the  Alkaline  Earths  dissolved  by  Hydrochlo- 

rate  of  Ammonia  and  Chloride  of  Sodium 236 

Production  of  Formic  Acid  in  Oil  of  Turpentine 236 

Precipitation  of  certain  Salts  by  excess  of  Acids,  by  M.  Wacken- 

roder 236 

Solubility  of  Salts  in  Pernitrate  of  Mercury     237 

On  Laurostearine,  by  M.  Marsson    237 

On  Laurostearic  Acid,  by  M.  Marsson 238 

On  the  Presence  of  Antimony  in  Arsenious  Acid   238 

Discovery  of  a  new  Metal,  Didym     239 

Meteorological  Observations  for  July  1842 239 

Table 240 


NUMBER  CXXXVII I. —OCTOBER. 

Mr.  Gulliver's  Contributions  to  the  Minute  Anatomy  of  Ani- 
mals.  No.  IV 241 

M.  Dufrenoy's  Description  of  Greenovite.    246 

Mr.  Smee's  New  Definition  of  the  Voltaic  Circuit,  with 
Formulae  for  ascertaining  its  Power 248 

The  Rev.  P.  Kelland's  Reply  to  some  Objections  against  the 
Theory  of  Molecular  Action  according  to  Newton's  Law.  .  . .    263 

Mr.  W.  H.  Balmain's  Observations  on  the  Formation  of  Com- 
pounds of  Boron  and  Silicon  with  Nitrogen  and  certain  Metals  270 

Prof.  Miller  on  the  Optical  Constants  of  Tourmaline,  Dioptase 
and  Anatase     277 


VI  CONTENTS  OF  VOL.  XXI. 

Page 
Messrs.  W.  Francis  and  H.  Croft's  Notices  of  the   Results  of 

the  Labours  of  Continental  Chemists  (continued)     278 

Mr.  John  Phillips  on  the  Occurrence  of  Shells  and  Corak  in  a 
Conglomerate  Bed,  adherent  to  the  face  of  the  Trap  Rocks  of 

the  Malvern  Hills 2  88 

Prof.  MacCullagh  on  the  Dispersion  of  the  Optic  Axes,  and  of 

the  Axes  of  Elasticity,  in  Biaxal  Crystals    293 

Mr.  G.  G.  Stokes's  Remarks  on  a  paper  by  Professor  Challis, 
*'  On  the    analytical  Condition  of  the  Rectilinear  Motion  of 

Fluids" 297 

The  Rev.  H.  Moseley  on  Conch yliometry    300 

Proceedings  of  the  Geological  Society 306 

London  Electrical  Society 310 

Chemical  Society     313 

Bichloride  of  Hydrogen 320 

On  the  Action  of  Chlorides  upon  Protochloride  of  Mercury    . .    320 

On  Cinchovatina — a  new  Vegetable  Alkali 323 

Preparation  of  pure  Potash  and  Soda 324 

Detection  of  Iodine  in  Bromides 324 

Preparation  of  Ferrocyanic  Acid  and  Ferridcyanide  of  Potassium    325 

Obituary     327 

Meteorological  Observations  for  August  1842     327 

Table 328 


NUMBER  CXXXIX. -NOVEMBER. 

Letter  addressed  by  M .  Edmond  Becquerel  to  the  Editors  of  the 
Annales  de  Chimie  et  de  Physique,  in  Reply  to  Mr.  Daniell's 
Letter  to  Mr.  R.  Phillips  on  the  Constant  Voltaic  Battery, 

inserted  in  the  Phil.  Mag.  for  April  1842    329 

Prof.  Grove's  Remarks  on  a  Letter  of  Professor  Daniell  con- 
tained in  the  Philosophical  Magazine  for  April   333 

Mr.  H.  Fox  Talbot  on  the  Iodide  of  Mercury 336 

On  the  Progress  of  Embryology  in  the  Year  1840 337 

Mr.  Earnshaw  on  the  Theory  of  Molecular  Action  according  to 

Newton's  Law :  in  Reply  to  Professor  Kelland    340 

The  Rev.  M.  O'Brien's  Additional  Remarks  upon  a  Com- 
munication of  Professor  Kelland,  published  in  the  Phil.  Mag. 

for  May  last    342 

Prof.  Kelland's  Vindication  of  himself  against  the  Charges  of 

the  Rev.  M.  O'Brien 344 

Dr.  Draper  on  certain  Spectral  Appearances,  and  on  the  disco- 
very of  Latent  Light 348 

Dr.  M.  Barry's  Note  regarding  the  Structure  of  Muscle 351 

Dr.  G.  Fownes  on  the  Preparation  of  Artificial  Yeast 352 

Mr.  H.  Croft  on  some  Salts  of  Cadmium 355 


CONTENTS  OF  VOL.  XXI.  Vll 

Page 
Mr.  Murchison  on  the  Salt  Steppe  south  of  Orenburg,   and 

on  a  remarkable  Freezing  Cavern 357 

Extracts  from  a  Letter  addressed  by  Sir  J.  F.  W.  Herschel  to 
Mr.  Murchison,  explanatory  of  the  Phenomena  of  the  Freezing 

Cave  of  Illetzkaya  Zatchita    359 

Sir  J.  F.  W.  Herschel  on  some  Phenomena  observed  on  Glaciers, 
and  on  the  internal  Temperature  of  large  Masses  of  Ice  or 
Snow,  with  some  Remarks  on  the  natural  Ice -caves  which 

occur  below  the  limit  of  perpetual  Snow 362 

Proceedings  of  the  Geological  Society 365 

Chemical  Society 378 

Royal  Irish  Academy 389 

— Royal  Astronomical  Society     397 

Institution  of  Civil  Engineers 401 

London  Electrical  Society     404 

New  Books  : — Newman  on  the  Difficulties  of  Elementary  Geo- 
metry, &c. — Logarithmic  and  Trigonometric  Tables,  &c.   . .    405 

Prof.  MacCullagh  on  the  Law  of  Double  Refraction 407 

Atomic  Weight  of  Elements 409 

On  a  very  curious  Fact  connected  with  Photography,  disco- 
vered by  M.  Moeser  of  Koenigsberg,  communicated  by  Prof. 

Bessel  to  Sir  D.  Brewster. 409 

Use  of  Iron  Wire  for  Secondary  Electro-magnetic  Coils 411 

Non-conversion  of  Calomel   into    Sublimate  by   the  Alkaline 

Chlorides    411 

Method  of  distinguishing  Zinc  from  Manganese  in  Solutions 

containing  Ammoniacal  Salts,  by  M.  Otto 412 

On  MM.  Varrentrapp  and  Will's  Method  of  determining  Azote 

in  Organic  Analyses,  by  M.  Reizet 412 

New  Double  Salt  of  Soda  and  Protoxide  of  Platina    413 

Composition  of  Conia    414 

Mr.  Luke  Howard's  Cycle  of  Eighteen  Years  in  the  Seasons 

of  Britain 415 

Meteorological  Observations  for  September  1842    415 

Table     416 


NUMBER  CXL.— DECEMBER. 

Prof.  Grove  on  a  Gaseous  Voltaic  Battery 417 

Prof.  Daniell  on  the  Constant  Voltaic  Battery 421 

The  Rev.  P.  Kelland  on  certain  Arguments  adduced  in  the  last 

Number  of  the  Philosophical  Magazine    422 

The  Rev.  Prof.  Challis  on  the  Analytical  Condition  of  Rectilinear 

Fluid  Motion,  in  Reply  to  Mr.  Stokes's  Remarks    423 

Dr.  A.  Waller's  Experiments  on  the  coloured  Films  formed  by 

Iodine,  Bromine,  and  Chlorine  upon  various  Metals    426 

Mr.  Earnshaw's  Reply  to  Professor  Kelland's  Defence  of  the 

Newtonian  Law  of  Molecular  Action     437 

The  Rev.  J.  Booth  on  a  Theorem  in  Analytical  Geometry  ....    444 


Vlll  CONTENTS  OF  VOL.  XXI. 

Page 
Messrs.  W.  Francis  and  H.  Croft's  Notices  of  the  Results  of  the 

Labours  of  Continental  Chemists  (continued)    446 

Dr.  Draper  on  a  new  Imponderable  Substance,  and  on  a  Class 

of  Chemical  Rays  analogous  to  the  Rays  of  Dark  Heat  ....    453 
Mr.  R.  Hunt  on  Thermography,   or  the  Art  of  Copying  En- 
gravings, or  any  printed  Characters  from  Paper  on  Metal 
Plates  ;  and  on  the  recent  Discovery  of  Moser,  relative  to  the 

formation  of  Images  in  the  Dark 462 

Mr.  Hopkins  on  the  Elevation  and  Denudation  of  the  District  of 

the  Lakes  of  Cumberland  and  Westmoreland 468 

Proceedings  of  the  Royal  Astronomical  Society 477 

London  Electrical  Society 484 

Cambridge  Philosophical  Society 485 

Use  of  Sulphate  of  Ammonia  in  Agriculture    488 

Chloride  of  Gold  as  a  Test  of  certain  Vegetable  Alkalies  ....    489 
Non-Decomposition  of  Vegetable  Alkalies  by  exposure  to  Fer- 
menting Bodies ■ , 490 

Preparation  and  Composition  of  Pepsin    491 

Action  of  Chlorides  on  some  Mercurial  Compounds,    by    M. 

Mialhe    492 

On  a  new  Mode  of  forming  Ammonia,  by  M.  Reizet 495 

Meteorological  Observations  for  October  1842    495 

Table 496 


NUMBER  CXLL— SUPPLEMENT  TO  VOL.  XXL 

Prof.  Marianini  on  the  Currents  produced  by  the  Actuation  or 

Induction  of  instantaneous  Electric  Currents   497 

Proceedings  of  the  Royal  Astronomical  Society     510 

Royal  Irish  Academy 532 

Geological  Society    540 

Index 562 


PLATE. 


I.— Linear  Solar  Spectra  with  their  corresponding  Tithonographs ;  illus- 
trative of  a  paper  by  Dr.  Dkaper. 


Errata. 

Page  43,  line  13  from  the  bottom,/or  (*+T)'  read  e  (*+T)\ 

44,  —      3,  put  sign  +  before   \/ . 

55,  —       7  from  the  bottom,  instead  of  "  M.  Catalan,"  read  "  Pro- 
fessor MacCullagh." 
176,  line  13,/or  quina  read  citichonia. 
473,  line  4  from  the  bottom,/or  Penim  read  Penine. 
529,  line  2  from  the  bottom,/or  node  read  note. 


THE 
LONDON,  EDINBURGH  and  DUBLIN 

PHILOSOPHICAL  MAGAZINE 

AND 

JOURNAL  OF   SCIENCE. 


[THIRD  SERIES.] 


JULY  1842. 


I.    On  the  Influence  of  the  Dew-point  on  Vegetables,  considered 

especially  with  reference  to  their  Temperature.     By  D.  P. 

Gardner,  M.D.,  Professor  of  the  Physical  Sciences,  fyc.  in 

Hampden  Sidney  College,  tyc,  Corresponding  Member  of  the 

New  York  Lyceum  qf  Natural  History*. 
HPHE  object  of  this  paper  is  to  establish  the  mutual  relation 
existing  between  the  temperature  of  plants  f,  their  eva- 
poration, and  the  amount  of  vapour  existing  in  the  atmosphere. 
The  subject  will  be  examined  under  four  heads,  which  have 
been  suggested  by  the  results  of  the  experiments  instituted, 
and  are  therefore  gradual  developments  of  the  proofs  by  which 
the  connexion  between  the  dew-point  and  temperature  of 
plants  is  sought  to  be  established. 

1st.  Certain  vegetables  are  without  any  specific  heat. 

2ndly.  The  variations  plus  or  minus  the  atmospheric  tem- 
perature observable  in  plants  are  owing  chiefly  to  the  state  of 
the  dew-point,  its  elevation  causing  an  increase  of  heat  by 
checking  evaporation,  and  its  depression  by  favouring  evapo- 
ration producing  coldness ;  in  other  words,  the  rate  of  evapo- 
ration, and  its  effect  in  producing  a  decrease  of  temperature  in 
plants,  is  directly  as  the  greatness  of  the  drying  power,  and 
inversely  as  its  diminution. 

3rdly.  The  sensible  heat  of  plants  is  directly  as  the  atmo- 
spheric temperature,  and  the  chemical  action  going  on  in  their 
cells ;  and  inversely  as  the  evaporation,  radiation  and  conduc- 

*  Read  before  the  Linnsean  Society,  November  16th,  1841,  and  now  com- 
municated at  the  request  of  the  Author,  by  J.  J.  Bennett,  Esq.,  Sec.  L.S. 

t  On  the  subject  of  the  heat  of  plants,  see  Meyen's  Report  for  1839,  in 
the  Annals  and  Magazine  of  Natural  History,  vol.  viii.  p.  27 ;  also  the 
original  paper  by  Vrolyk  and  De  Vriese,  in  the  same  work,  vol.  vii.  p.  161 
— Edit. 

Phil,  Mag,  S.  3.  Vol.  21.  No.  135.  July  1842.         B 


2       Professor  Gardner  on  the  Influence  of  the  Dew-point 

tion  of  the  soil  and  surrounding  air :  to  this  we  add,  chemical 
action  increases  with  atmospheric  temperature,  &c.  &c,  and 
consequently  the  amount  of  heat  resulting  therefrom. 

4thly.  A  review  of  the  foregoing  doctrine,  with  some  re- 
marks on  apparent  anomalies. 

§  I .   That  certain  Vegetables  are  without  any  specific  heat. 

A  number  of  insulated  measures  of  the  temperature  of 
flowers  has  hitherto  been  admitted  into  the  books  on  vege- 
table physiology  as  the  whole  of  our  information  on  the  sub- 
ject of  vegetable  heat;  and  these  measures  have  been  re- 
ceived with  distrust  or  altogether  denied.  M.  de  Lamarck 
observed  an  increase  of  temperature  in  the  spadix  of  Arum 
vulgare,  which  M.  Sennebier  afterwards  measured  and  found 
equal  to  7°  C.  above  the  atmosphere.  The  German  natu- 
ralist Schultz  found  a  flower  of  Calladium  pinnatifidum  at  19° 
to  20°  C.  when  the  surrounding  air  was  only  15°  C.  Messrs. 
Hubert  and  Bory  measured  the  temperature  of  the  spadix  of 
Arum  cordifolium  in  the  Isle  of  France,  and  found  it  at  sun- 
rise 4"Jf°  to  49°  C. ;  the  atmospheric  temperature  being  only 
19°  C.  M.  de  Saussure  carried  his  experiments  further,  and 
with  the  differential  thermometer  ascertained  an  increase  of~°C. 
in  the  male  flowers  of  the  melon  and  other  Cucurbitaceae. 

Hypotheses  have  not  been  wanting  to  explain  the  reason 
why  flowers  should  enjoy  a  more  elevated  temperature  than 
the  other  parts  of  the  plant.  Mr.  Murray  imagined  it  was 
due  to  their  colour.  Brongniart  ascribed  it  to  the  increased 
action  of  the  molecules  interested  in  the  process  of  fecunda- 
tion. Others  have  adopted  the  more  plausible  idea,  that  it  de- 
pended upon  increased  chemical  action,  as  the  absorption  of 
oxygen  by  the  petals,  &c.  of  the  flower. 

But  Messrs.  Treviramis,  Goppert  and  Schubler,  altogether 
deny  that  flowers  give  any  indications  of  an  increase  of  tem- 
perature. M.  Aug.  de  Candolle  ascribes  this  denial  to  the 
erroneous  conclusions  at  which  these  botanists  arrived  from 
experimenting  on  imperfect  plants ;  since  his  experience  at 
Montpellier  had  led  him  to  the  same  opinion  as  Saussure 
and  others. 

Placed  in  so  embarrassing  a  situation,  our  only  resource 
was  to  undertake  a  new  series  of  experiments  upon  the  sub- 
ject ;  for  although  the  mass  of  evidence  appears  to  be  in  fa- 
vour of  the  existence  of  a  specific  temperature  in  flowers,  yet 
the  measures  given  are  too  dissimilar  to  prove  satisfactory, 
and  the  experiments  appear  to  have  been  performed  in  too 
loose  a  manner  to  silence  opposition.  The  mere  introduction 
of  a  thermometer  into  a  flower  is  a  process  undeserving  any 


on  Vegetables,  with  reference  to  their  Temperature.        3 

serious  attention :  the  state  of  the  atmosphere  has  been  omitted, 
and  in  other  respects  the  data  are  so  imperfect,  as  to  exclude 
the  possibility  of  our  repeating  any  of  the  experiments  given 
under  similar  circumstances. 

The  instrument  with  which  their  measures  have  been  made 
is  altogether  too  bulky  in  such  delicate  researches ;  for  al- 
though the  bulb  of  a  thermometer  may  be  thrust  into  a  pump- 
kin flower  or  tulip  with  tolerable  facility,  yet  the  contact  of 
the  circumambient  air  is  not  completely  cut  off  by  the  shape 
of  the  flower ;  and  if  the  fingers  or  any  other  contrivance 
be  used  as  a  means  of  closing  the  corolla  upon  the  thermo- 
meter, the  temperature  of  the  new  body  complicates  the 
result.  Even  when  introduced  with  all  care,  a  bulk  of  mer- 
cury or  air  of  as  many  cubic  lines  as  the  flower  has  super- 
ficial measure,  in  either  case  an  imperfect  conductor,  can  only 
give  a  doubtful  result.  It  is  too  large  in  most  cases,  and  must 
be  confined  to  experiments  upon  a  few  scattered  flowers ;  nor 
can  it  in  any  instance  be  made  use  of  to  obtain  a  set  of  mea- 
sures over  the  whole  plant ;  most  stems  would  be  crushed  in 
attempting  to  introduce  it ;  and  even  if  we  succeeded  so  far, 
the  measure  obtained  must  be  imperfect,  from  the  injury  in- 
flicted upon  the  plant  and  the  small  amount  of  mercury  or  air 
in  absolute  contact. 

These  considerations  have  induced  me  to  make  use  of  a 
thermo-electric  pair  and  the  galvanometer  as  the  most  suitable 
thermoscope.  The  pair  consists  of  a  tinned  iron  and  copper 
wire,  each  y^th  of  an  inch  in  diameter,  soldered  together  at  one 
extremity  with  tin  for  T\,th  of  an  inch,  and  sharpened  so  as  to 
enter  with  slight  force  any  part  of  a  plant ;  the  wires  used  were 
about  nine  inches  long,  and  were  passed  through  a  large  bung, 
so  that  the  fingers  might  not  approach  the  junction,  the  cork 
serving  as  anon-conducting  handle,  and  being  sufficiently  re- 
moved to  hinder  the  possibility  of  producing  a  current  of  ther- 
mo-electricity by  radiation  from  the  hand.  The  galvanometer 
employed  was  the  simple  multiplier  of  Schweigger ;  the  axis 
being  suspended  by  a  fibre  of  raw  silk  and  bearing  two  needles 
perfectly  astatic,  and  also  at  the  lower  end  a  parallelogram 
of  tin-foil  which  was  immersed  in  a  vessel  of  water  beneath 
the  galvanometer ;  the  object  of  this  addition  is  to  steady  the 
vibrations  of  the  needles,  as  shown  by  Dr.  Draper  (Phil. 
Journ.).  The  whole  arrangement  was  covered  by  a  glass 
bell-jar,  having  a  graduated  arc  pasted  on  the  inside  at  an 
appropriate  height,  which  by  moving  the  glass  vessel  can  be 
brought  to  any  place  so  as  to  arrange  the  zero  point  with 
great  facility ;  the  upper  needle  also  bore  a  fine  wire  standing 
up  at  right  angles  from  its  extremity,  which  as  the  needle  is 

B2 


4      Professor  Gardner  on  the  Influence  of  the  Dew-point 

deflected  plays  across  the  arc  and  tends  to  assist  the  admea- 
surement. 

The  thermo-electric  pair  and  galvanometer  can  be  made 
an  extremely  delicate  differential  thermometer ;  and  from  ex- 
periments already  made  by  Drs.  Forbes,  Ritchie,  Draper,  &c., 
we  are  justified  in  stating  that  the  degree  of  variation  of  the 
astatic  needles  is  very  uniform  for  equal  increments  of  heat, 
in  cases  where  the  total  amount  of  variation  is  as  limited  as 
in  the  following. 

In  obtaining  the  numbers  of  the  tables,  or  the  measures  of 
temperature,  the  pointed  extremity  of  the  pair  was  thrust  into 
the  parts  of  the  plant  specified,  care  being  taken  to  avoid 
contact  by  the  fingers  with  either  the  plant  or  thermoscope  ; 
the  numbers  given  are  the  mean  of  at  least  five  measures  made 
by  forming  and  breaking  the  electric  circle.  The  same  pair 
and  galvanometer  were  used  throughout,  and  the  value  of  a 
degree  of  the  index  equals  two  elevenths  of  a  degree  of  Fahr- 
enheit, or  1°  F.  =  5°' 5  galvanometer.  It  is  well  to  observe  here 
that  the  whole  of  the  junction  of  the  thermo-electric  pair  must 
be  introduced  into  the  plant,  otherwise  the  current  of  electri- 
city does  not  circulate  freely  through  the  length  of  the  wires, 
but  passes  round  from  the  warm  to  the  cold  parts  of  the  junc- 
tion, forming  a  circle  that  does  not  include  the  galvanometer, 
and  therefore  producing  no  deflection  of  the  needles. 

The  dew-point  marked  in  the  tables  was  taken  immediately 
before  and  after  each  series  of  measures,  and  if  any  difference 
existed,  the  mean  adopted. 

The  height  of  the  thermometer  is  marked  both  at  the  time 
of  the  deposit  of  dew  upon  the  exterior  of  a  glass  of  iced  water 
and  its  vanishing.  The  drying  power,  which  is  Dr.  Dalton's 
expression  for  the  difference  between  the  dew-point  and  at- 
mospheric temperature,  is  also  marked  in  the  tables ;  and  it  is 
well  to  remark,  that  that  great  philosopher  has  ascertained 
that  the  amount  of  evaporation  is  the  same  for  all  temperatures 
if  the  drying  power  be  the  same. 

The  experiments  were  performed  in  the  shade,  every  dis- 
turbing cause,  as  currents  of  air,  motion,  &c.  being  avoided. 
The  thermometer  hanging  at  the  side  of  the  galvanometer, 
and  the  dew-point,  &c,  were  all  estimated  at  the  same  spot. 

Arum  Walteri  (foliis  sagittatis)  was  preferred  for  experi- 
ment ;  because  it  was  in  this  genus  Lamarck,  Sennebier,  &c. 
noticed  the  striking  variations  of  temperature  recorded  in  the 
commencement  of  this  section  ;  it  moreover  flourished  in  my 
immediate  neighbourhood,  and  was  of  convenient  size  to  esta- 
blish a  complete  series  of  measures  upon.  The  plants  were 
dug  from  the  marsh  in  which  they  grew,  with  several  pounds 


on  Vegetables,  with  reference  to  their  Temperature.       5 

of  native  soil  around  their  bulbs,  shortly  after  sun-rise,  placed 
in  a  wooden  box  and  carried  at  once  to  the  place  of  destina- 
tion about  200  yards  distant ;  after  having  been  left  a  suffi- 
cient time  to  allow  the  soil  to  radiate  any  excess  of  heat,  or 
about  two  hours  under  any  circumstances,  the  measures  were 
commenced,  and  recorded  at  the  time.  Other  examinations 
of  the  same  group  of  plants  took  place  however  at  different 
periods  in  the  day,  the  plants  being  uninjured  and  vigorous. 

It  is  necessary  I  should  observe  here,  that  all  attempts  made 
to  examine  plants  in  situ  failed  from  various  causes ;  the  dif- 
ference of  temperature  between  parts  exposed  to  the  sun  and 
those  in  the  shade ;  the  impossibility  of  managing  the  delicate 
thermoscope  in  the  open  air ;  the  disturbing  effects  of  cur- 
rents, gusts  of  wind,  &c. ;  nor  does  it  appear  to  me  at  all 
necessary  that  such  examinations  should  be  made,  even  if  the 
results  could  be  depended  upon.  The  measures  derived  from 
a  vigorous  plant  removed  under  the  foregoing  circumstances 
are  fully  as  trustworthy;  and  when  the  great  deviations  of  the 
needles  come  to  be  considered,  even  the  most  sceptical  will 
allow  that  the  difference  of  situation  would  not  have  influenced 
the  result  beyond  a  few  degrees ;  in  which  I  may  possibly  be 
in  error ;  but  upon  the  general  fact  there  cannot  be  any  dis- 
pute. 

So  far  the  tables  introduced  may  be  regarded  as  exhibiting 
the  measures  made  upon  one  species ;  but  although  it  has  not 
been  considered  necessary  to  tabulate  the  other  results,  yet  a 
similar  series  of  experiments  were  made  on  the  undermen- 
tioned plants,  as  far  as  it  was  found  practicable,  but  none  of- 
fered the  advantages  possessed  by  Arum. 

The  examination  of  these  plants  gave  the  same  general  result, 
and  they  may  therefore  be  dismissed,  after  simply  stating  that 
they  corroborate  in  all  respects  the  observations  hereafter  to 
be  made  on  the  subject  of  vegetable  temperature,  &c. 

Symphytum  officinale,  Pastinaca  sativa,  Cicuta  maculata, 
Asclepias  obtusifolia  et  syriaca,  Arctium  Lappa,  Sagittaria  sa- 
gittifolia,  Rumex  crispus,  Lobelia  cardinalis,  Daucus  Carota, 
Datura  Stramonium,  Delphinium  consolidum,  Cynoglossum  offi- 
cinale, &c. 

The  botanist  will  recognise  in  this  list,  plants  of  sufficient 
bulk  to  allow  of  the  introduction  of  the  thermo-electric  pair. 
They  are  also  very  frequently  met,  and  were  chosen  partly 
from  this  cause,  as  well  as  from  their  proximity  to  the  labora- 
tory. The  list  could  be  elongated  indefinitely  if  a  smaller  pair 
were  used,  but  it  is  unnecessary  to  introduce  other  cases,  as 
each  observer  can  modify  his  apparatus  as  to  the  fineness  of 
the  elements  according  to  his  pleasure. 


6      Professor  Gardner  on  the  Influence  of  the  Dew-point 

Lest  the  deviation  of  the  needle  of  the  galvanometer  should 
be  due  to  any  other  cause  than  a  current  produced  by  the 
temperature  of  the  plants,  several  experiments  were  made  to 
decide  this  point.  The  magnetic  influence  of  the  tinned  iron, 
the  action  of  vegetable  acids,  friction,  radiation  from  the  per- 
son or  surrounding  objects,  were  all  examined,  and  it  was 
found,  that  under  the  precautions  adopted,  all  these  disturb- 
ing causes  were  neutralized,  so  that  all  the  measures  given 
are  solely  attributable  to  the  presence  of  sensible  heat  in  the  plant . 

Where  more  than  one  measure  is  recorded,  it  was  either 
made  upon  different  parts  of  the  same  plant,  or  at  different 
times  upon  different  parts ;  in  the  latter  case,  the  time  which 
had  elapsed  between  the  measures  is  also  recorded. 

Table  A. 

June  8th,  1839.  A  vigorous  group  of  Arum  JValteri  with 
well-developed  spathae,  and  several  pounds  of  mud  in  situ. 

Thermometer  66°  Fahr.  Dew-point  54>°.  Drying  power  12°. 
Clear.      . 


Parts  of  the  plant  examined. 

Two  hours 
after  col- 
lection. 

Three  hours 
after  col. 
lection. 

+  14-8 
+  14-8 
0 

-  7-15 

—20-9 
-20-9 

-20-9 

All  in  degrees 
of  galvanometer. 

"Agreeing  with 
the  mercurial 
thermometer, 
or  3°-8  Fahr. 
below  the  at- 
<{    mospheric 
l_  temperature. 

Fully  developed  leaf  stem    

Stem  (or  rather  collection  of  pe- "] 
tioles)oneinch  below  soil  with-  I 

Stem,  six  inches  below  soil,  co-  \ 
vered  with  adherent  earth   ...  / 

Table  B. 
June  11th.  Pastinaca  sativa  in  flower,  with  adherent  soil. 
Thermometer  81°  Fahr.  Dew-point  66°.  Drying  power  15°. 
Clear. 


Farts  of  the  plant  examined. 

Galvanometer. 

Stem,  near  umbel  with  young  \ 

+  8- 

0 

0 

-  1-4 

-106 

—20 

-20 

—20 

+  8- 
0 
0 

fCorrespond- 

1     ing  with  a 

depression  of 

a  little  more 

than  3-5°  of 

<     Fahrenheit's 

I    thermometer. 

Stem  at  3  feet,  %\  feet  and  1  foot  \ 

Stem  six  inches  above  grouud... 
Stem  one  inch  above  ground   ... 

Larger  branches  of  root  

Temperature  of  the  soil 

on  Vegetables,  with  reference  to  their  Temperature,  7 

Table  C. 
June  12th.    Arum  Walteri,  a  fresh  group,  &c.     Thermo- 
meter 86°  Fahr.  Dew-point  64°.  Drying  power  22°.  Clear. 


Parts  of  the  plant  examined. 

Galvanometer. 

Male  &  female  portions  of  spadix 

0 
0 
0 

+  1 

0 
-1-4 
-205 
-20-5 
—20-5 

0 
0 
0 

+  V2 

0 
-1-4 
-20-5 

0 

0 

+  1-5 

0 

0 

0 
0 

+1 

0 

"Agreeing 
with    the 
thermo- 
metric 
tempera- 
ture of 
3°-6Fahr. 
f  below  the 
\  air. 

Collection  of  leaf-stems  (stem) 
Stern  three  inches  above  soil  ... 

Bulb  

Soil    

Table  D. 
June  7th.  Arum  Walteri,  &c.,  three  hours  after  collection. 
Thermometer  64°  Fahr.    Dew-point  51°.    Drying  power  13°. 
Fahr.  Clear. 


Parts  of  the  plant  examined. 

Spadix  in  vigorous  /  male  part.., 
action \  female  part 

Petioles  of  various  leaves 

Midribs  of  various  leaves 

Stem  (collection  of  petioles  \ 
two  inches  above  soil   J 

Stem  one  inch  above  soil 

Stem  surrounded  by  soil  

Temperature  of  soil , 


Galvanometer. 


+  13 
+  13-7 
+  8-8 
+  13 

+  2 

-  2-5 

—14 

-14 


+  8-8 
+  12-5 


14 


+  7 
+  12 


-14 


+  8 
+  11 

+  7 


-14 


("Agreeing 

with  the 

i    thermo- 

t  metric 
measure 


To  these  tables  many  others  might  be  added,  as  they  all 
tend  to  establish  the  same  point.  If  we  examine  them  solely 
to  ascertain  whether  they  afford  any  proof  of  the  existence  of 
a  certain  specific  or  vegetable  heat,  we  are  irresistibly  led  to 
acknowledge  that  the  proof  is  against  any  such  vital  agent,  and 
we  deduce  this, — . 

1st.  Because  in  the  four  tables  the  atmospheric  tempera- 
tures quoted  are  66°,  81°,  86°  and  64°  respectively,  and  yet 
the  plant  varies  with  each. 

2d.  We  observe  that  the  temperature  of  the  soil  is  thesame 
as  that  of  the  subterrene  stem  or  root,  and  that  the  excess  of 
temperature,  if  any  such  exist,  is  found  in  parts  remote  from 
the  soil,  and  in  which  vital  action  is  taking  place.  It  is  na- 
tural that  the  root  should  be  of  the  same  temperature  as  the 
earth,  for  along  its  vessels  are  passing  the  fluids  derived  from 
the  soil ;  and  the  conducting  power  of  the  latter  must  tend  to 


8       Professor  Gardner  on  the  Influence  of  the  Dew-point 

keep  down  the  heat  of  the  root,  even  when  chemical  action  is 
taking  place  most  actively  in  its  structure. 

We  are  therefore  justified  in  asserting  that  vegetables  (so  Jar 
as  annuals  and  perennials)  possess  no  specific  heat  similar  to 
that  belonging  to  mammals.  Sec,  but  that  their  temperature  varies 
'with  the  atmosphere  within  certain  limits. 

§  2.  That 'the  variations  plus  or  minus  the  atmospheric  tempera- 
ture are  partly  owing  to  the  state  of  the  dew-point,  fyc.  (p.l.) 
It  is  well  known  that  evaporation  cannot  take  place  from  any 
surface  unless  the  temperature  and  dew-point  differ ;  for  as 
a  given  bulk  of  air  is  only  capable  of  retaining  a  certain 
amount  of  watery  vapour  in  solution  at  a  known  tempera- 
ture, it  follows,  that  if  the  dew-point  indicates  that  amount  of 
saturation,  all  evaporation  must  cease  so  long  as  these  condi- 
tions are  maintained.  It  is  also  well  known,  that  the  heat 
produced  by  chemical  and  vital  actions  taking  place  in  the 
highest  animals  is  antagonized  by  evaporation  from  the  skin 
and  lungs,  the  tendency  of  which  is  to  produce  coldness.  We 
have  here  therefore  a  source  of  heat  and  its  opposite  which 
likewise  exists  in  plants,  with  this  difference,  that  whilst  the 
former  power  is  considerably  lessened,  the  latter  is  increased 
in  consequence  of  the  extensive  surface  from  which  evapora- 
tion takes  place. 

But  the  rapidity  of  evaporation  is  dependent  upon  several 
circumstances,  as  the  amount  of  drying  power,  velocity  of  the 
wind,  extent  of  surface,  &c. ;  of  these  the  first  is  the  most  im- 
portant and  easiest  of  examination.  To  show  its  influence, 
we  introduce  three  other  tables,  selected  as  illustrating  the 
influence  of  the  amount  of  drying  power  most  extensively. 

Table  E. 
June  12th.     Arum  Walteri;  soil  extremely  wet,  and  conse- 
quently adhering  less  firmly  than  in  the  previous  cases.  Ther- 
mometer 85°.  Dew-point  60°.  Drying  power  25°.  Clear. 


Parts  of  the  plant  examined. 

Galvanometer. 

-5 
-5 
-5 

0 

-2 
0 
-9 
+  2 
-7-5 
—  24 
-27 
-30 
-30 

-5 

-5 

-5 

0 

0 

0 

-8- 
-24 

-5 

-3-6 

-5 

-  -2 

-  -2 

-7-5 

—5 

-5 

—5 

0 

Spatha  open  and  J  male  portion 

spadix  active    \  female  

Male  spadix  giving  off  pollen  ... 

Expanded  leaf,  midrib 

Stem,  or  collection  of  petioles 

Stem  three  inches  below  soil  ... 
Temperature  of  the  soil  

f  With 

I  meter. 

on  Vegetables,  'with  reference  to  their  Temperature.      9 

In  this  table  we  are  presented  with  an  unusually  high 
amount  of  drying  power,  the  effect  of  which  is  to  produce  so 
rapid  an  evaporation,  that  the  heat  generated  in  the  most  ac- 
tive parts  of  the  plant  is  neutralized.  This  group  of  plants, 
although  very  vigorous  when  examined,  was  drooping  in  six 
hours  after  from  excessive  evaporation. 

Table  F. 
June  14th.  Arum  Walteri,  with  plenty  of  moist  earth.  Ther- 
mometer 86°  Fahr.     Dew-point  62°.     Drying  power   24-°. 
Clouds  rising. 


Parts  of  the  plant  examined. 

Galvanometer. 

Young  spadix,  male  portion    ... 

-4 

-4-5 

-5 

—  5    ' 

-5-5 
—5 

Expanded  spatha  {^^pa'dix 

midrib  ... 

-5 
-5 

-6 
-5 

midrib 

-9 
-6 

—9 
-6 

Main  stem  one  inch  above  soil 

-36 

three  inches  below 

-55 
-56 

... 

/  Agreeing  with  the 
\   thermometer. 

Table  G. 
The  same  group  as  in  Table  E,  again  examined  six  hours 
after  collection,  about  half  an  hour  after  the  falling  of  rain. 
Plants  very  vigorous.     Thermometer  75°  Fahr.     Dew-point 
65°.     Drying  power  10°.    Clearing. 


— I 

Parts  of  the  plant  examined. 

Galvanometer. 

Young  spatha,  male  part 

+  8 
+8 
+8-5 
+8 
+  10 
+  '5 
+  12 
—  2 
-30 
-32 

+9 

+7-8 
+  8-8 
+  9 

0 

+  8 

+  10 

("Agreeing  with 
•j  the  thermome- 
Lter. 

Young  expanded  leaf,  midrib  ... 

six  inches  below    ... 

Temperature  of  soil 

In  tables  E,  F  and  C  of  the  previous  section  the  drying  power 
is  extremely  high,  22°,  24°,  and  25°  Fahr. ;  the  effect  accord- 
ing to  hypothesis  should  be  an  exalted  evaporation,  and  we 
find  accordingly  that  all  parts  of  the  plant  in  these  three  tables 
exhibit  a  temperature  below  that  of  the  atmosphere. 


10    Professor  Gardner  on  the  Influence  of  the  Dem-point 

The  tables  G  and  A  and  D  of  section  the  first  are  of  a  dif- 
ferent class ;  in  these  the  drying  power  varies  from  10°  to  12° 
and  1 3° ;  being  about  half  of  the  power  in  the  above  tables, 
and  representing  the  air  more  saturated  with  watery  vapour, 
and  therefore  less  conducive  to  evaporation.  In  these  tables 
we  remark  an  uniform  elevation  of  ■  temperature  in  all  the 
highly  organized  parts  of  the  plant;  notwithstanding  the  minus 
measures  of  the  root  from  contact  with  a  moist  and  therefore 
evaporating  soil ;  a  good  illustration,  en  passant,  of  the  non- 
conducting nature  of  living  vegetable  tissues. 

Not  to  become  diffuse,  we  perceive  in  these  results, — 
1st.  An  uniformity  which  recommends  them  to  our  reason. 
2ndly.  They  are  in  conformity  with  the  experience  of  man- 
kind. The  effects  of  moist  air  on  vegetation  is  known  to  all, 
the  rapid  growth,  the  vigour  of  plants,  or  to  speak  more  scien- 
tifically, the  activity  of  the  chemical  and  organic  actions  which 
maintain  life  are  fully  manifest.  The  result  is  an  increment 
of  temperature  in  exact  proportion  to  the  varying  activity  of 
each  organ,  whether  in  the  respiration  of  the  leaf  or  the  ge- 
nerative functions  of  the  parts  appointed  to  the  reproduction 
of  the  species. 

The  effects  of  a  drought  are  no  less  apparent ;  the  leaves 
hang  down ;  there  is  an  air  of  listlessness  about  plants  very 
analogous  to  the  effects  of  heat  upon  the  human  frame,  and 
due  to  the  undue  evaporation. 

How  firm  and  succulent  is  the  state  of  a  leaf  during  moist 
weather ;  how  exsiccated  and  flabby  during  a  dry  season  !  of 
this  the  tobacco  planters  in  Virginia  are  so  well  aware,  that 
they  esteem  moist  foggy  weather  favourable  when  gathering 
their  crop.  It  is  somewhat  curious  that  these  remarks  apply 
to  the  human  family ;  the  natives  of  moist  countries,  as  the 
Netherlands,  England,  &c,  being  of  fuller  habit  than  those  who 
live  in  arid  regions ;  this  similitude  does  not  however  extend 
so  far  as  in  plants,  from  the  effects  of  the  diseases  prevalent  in 
swampy  countries.  It  gives  me  great  pleasure  here  to  recom- 
mend the  paper  of  Mr.  Hopkins  in  the  London  and  Edin- 
burgh Philosophical  Magazine  for  February  1839,  on  Malaria, 
in  which  he  examines  the  influence  of  the  hygrometrical  state 
of  the  air  upon  animal  life. 

At  this  stage  of  the  investigation  it  is  necessary  to  meet  an 
objection  already  urged  against  the  foregoing  doctrine,  that 
it  levels  the  principle  of  life  in  vegetables  to  mere  chemical 
action.  We  do  not  hold  any  such  view.  We  simply  claim 
that  the  sensible  caloric  generated  by  plants  is  the  result  of 
internal  action;  the  amount  of  caloric  is  also  more  or  less,  ac- 
cording to  the  activity  of  the  evaporation,  the  influence  of  high 


on  Vegetables,  with  reference  to  their  Temperature.        11 

temperature  radiation,  and  conduction  of  the  soil.  The  or- 
ganic molecule  of  plants  is  not  a  mere  compound  atom,  for  it 
is  beyond  the  art  of  the  chemist  to  create  it  synthetically. 

But,  further,  to  meet  objections  of  this  kind,  and  convince 
ourselves  of  the  influence  exercised  by  evaporation  upon  the 
temperature  of  vegetable  substances,  we  resolved  to  have  re- 
course to  experimental  proof  of  a  direct  nature.  For  this 
purpose  an  experiment  made  by  Dr.  Hales  (Statical  Essays, 
exp.  30)  upwards  of  a  century  ago,  was  repeated  with  such 
modifications  as  to  suit  our  purpose. 

A  green  apple,  about  l±  inch  in  diameter  with  a  cluster 
of  leaves,  was  plucked  from  the 
tree;  and  the  stem  introduced 
through  a  cork  into  a  glass  tube 
filled  with  water,  to  the  lower 
end  of  which  a  smaller  tube  was 
cemented,  the  extremity  passing 
downwards  into  a  cistern  of  de- 
coction of  logwood  ;  the  appa- 
ratus being  supported  in  the  ver- 
tical position  by  a  retort-stand, 
as  represented  in  the  sketch; 
and  being  found  air-tight,  the  fol- 
lowing experiments  were  made. 
The  temperature  of  the  apple 
was  estimated  at  given  intervals 
with  the  thermo-electric  pair,  at 
the  same  time  the  drying  power 
and  elevation  of  the  coloured 
fluid  in  the  smaller  tube  was  ex- 
amined, and  the  measures  tabulated  for  the  purpose  of  ex- 
amining the  connexion  of  these  phenomena  at  a  coup  d'ceil. 
A  further  experiment  was  then  made  by  covering  the  apple 
and  its  leaves  with  a  delicate  caoutchouc  bag,  so  as  to  arrest 
evaporation,  and  after  a  given  interval  examining  the  tempe- 
rature of  the  fruit  and  elevation  of  the  coloured  fluid.  These 
experiments  were  repeated  many  times,  but  it  is  unnecessary 
to  adduce  more  than  two  series  in  this  place. 

Table  H. 

June  14th.    An  apple  with  twelve  leaves,  examined  imme- 
diately after  collection  at  lh  45'  p.m 


Examined 

at 
intervals  of 

Height  risen 

in 

interval. 

Galvano- 
meter. 

Temp, 
by 

Therm. 

Dew- 
point. 

Drying 
power. 

State  of  the 
Atmosphere. 

15' 
18' 
15' 
15' 

T8W  inch. 

9 
TIT 

tVtt 

& 

TV 

0 
+  -5 
+3-6 
+  5-5 

84  F. 
84 
80 
76 

64 
65 
63 
63 

20 
19 
17 
13 

Cloudy. 
Very  cloudy. 
Thunder,  &c. 
Rain  storm. 

12     Professor  Gardner  on  the  Influence  of  the  Dew-point 

After  a  delay  of  12'  the  caoutchouc  bag  was  used  and  tied 
tightly  around  the  stem,  and  after  1 7'  the  bag  was  pierced 
by  the  electric  pair,  the  results  being, — 


Examined 

at 
intervals  of 

Height  risen 

in 

interval. 

Galvano. 
meter. 

Temp.       Dew. 

tu  y    -     point. 
Therm.      * 

Drying 
power. 

State  of  the 
Atmosphere. 

17' 

6 
TtT 

+  13-75 

80         67 

13 

Clear. 

Beyond  this  period  it  is  impossible  to  examine  the  gauge,  for 
the  included  stem  begins  to  give  off  gas  into  the  water,  and 
therefore  partially  arrests  the  ascent  of  the  coloured  fluid. 

Table  I. 
June  15th.  Experiment  as  before,  time  of  collection  9h  35'. 


Examined 

at 
intervals  of, 

Height  risen 

in 

interval. 

Galvano- 
meter. 

Temp. 

by 
Therm. 

Dew- 
point. 

Drying 
power. 

State  of  the 
Atmosphere. 

j 

9h35' 
20' 
35' 

0 

lVAuich. 

1.    6 

1    TTT 

-30 
-2-5 
—  1-6 

73 

72 

72 

53 

55 

57 

20 
17 
15 

Fair. 

Cloudy. 

Cloudy. 

The  fruit  and  leaves  were  entirely  covered  with  the  caout 
chouc  at  10h  40',  and  pierced  after  35/  delay. 

35' 

7 
TV 

+  15-0 

74 

59 

15 

Cloudy. 

The  coldness  of  the  fruit  in  the  three  first  measures  of  the 
table  I.  was  due  to  the  presence  of  a  little  external  moisture, 
and  the  greater  temperature  of  the  room  than  the  external 
air. 

In  both  these  tables  the  effect  of  arresting  the  evaporation 
is  extremely  apparent  by  an  elevation  of  8^°  and  160,6  re- 
spectively ;  it  is  to  be  observed,  however,  that  the  drying  power 
given  in  the  two  additional  tables  represent  the  external  and 
not  internal  measure;  the  saturation  within  the  caoutchouc- 
bag  being  probably  greater.  In  the  table  H.  there  is  another 
coincidence  worthy  of  remark,  the  gauge  marks  a  decreasing 
power  of  suction  on  the  part  of  the  apple  as  its  temperature 
increases  and  the  evaporation  decreases,  showing  a  compen- 
sation between  the  amount  of  perspiration  of  the  leaves  and 
fruit  and  the  supply  of  fluid. 

Without  detaining  the  reader,  it  appears  that  the  foregoing 
tables  prove, — 

1st.   That  the  temperature  varies  with  the  drying  power. 

2ndly.  That  the  amount  of  evaporation  and  its  effects  in  pro- 


on  Vegetables,  with  reference  to  their  Temperature.        13 

during  coldness  is  directly  as  the  greatness  of  the  drying  power, 
and  inversely  as  the  approximation  of  the  dew-point  to  the  at- 
mospheric temperature. 

§  3.  The  sensible  heat  of  plants  is  directly  as  the  atmo- 
spheric temperature  and  the  chemical  action  going  on  in  their 
cells,  and  inversely  as  the  radiation,  evaporation  and  con- 
duction together,  tyc.  (p.  1 .) 

We  have  introduced  this  postulate  rather  to  give  complete- 
ness to  the  subject  than  to  enter  into  any  lengthened  examina- 
tion. That  it  is  true,  can  be  readily  shown  by  a  few  references 
to  the  foregoing  tables ;  the  proofs  drawn  may  be  conveniently 
ranged  under  three  heads : — 

1st.  The  temperature  of  plants  varies  nearly  with  the  at- 
mosphere, the  greatest  difference  measured  being  about  5° 
Fahrenheit. 

2ndly.  The  parts  in  which  the  greatest  exhibitions  of  tem- 
perature above  the  air  have  been  witnessed  are  the  seat  of  ac- 
tive chemical  and  organic  action,  as  the  ovaries,  male  spadix, 
midrib  of  leaves,  &c,  the  stem  being  seldom  above  or  below 
the  external  temperature. 

3rdly.  Roots  and  subterrene  stems  are  of  the  same  tempe- 
rature as  the  soil,  and  generally  below  the  atmosphere,  in  con- 
sequence of  evaporation  taking  place  from  the  earth.  This 
diminished  temperature  in  the  plant  must  depend  partly  upon 
conduction.  That  vegetables  also  lose  heat  by  radiation,  is 
shown  by  the  copious  deposit  of  dew  seen  upon  their  leaves 
after  a  clear  chilly  night. 

§  4".  A  review  of  the  subject,  with  some  remarks  on  apparent 

anomalies. 

Since  the  preceding  experiments  were  made  there  has  been 
published  in  the  Journal  de  Chimie,  an  article  on  vegetable 
heat  by  M.  Dutrochet*.  He  inclosed  a  dead  and  living 
plant  in  an  atmosphere  saturated  with  moisture,  and  examined 
their  temperature  with  Breschet's  physiological  pair.  The 
result  of  his  experiments  brought  him  to  the  conclusion,  that 
living  plants  possessed  a  temperature  that  exceeded  the  atmo- 
spheric temperature  by  one-third  centigrade  as  a  maximum. 
Van  Beck  has  since  repeated  the  experiments  of  M.  Dutro- 
chet  and  arrived  at  an  opposite  conclusion,  viz.  that  the  living 
plant  betrayed  two-thirds  centigrade  as  a  maximum  below  the 
dead  plant. 

Independently  of  the  discordance  in  these  measures,  we 
cannot  understand  how  a  plant  can  be  said  to  possess  a  spe- 

*  The  author  did  not  see  the  original  paper,  but  an  extract  in  the  Edin- 
burgh Philosophical  Journal  of  Professor  Jameson,  1840. 


14  Prof.  Gardner  on  the  Influence  of  the  Dew-point  on  Vegetables. 

cific  temperature  that  varies  within  one-third  plus  or  minus 
the  atmospheric  temperature,  which  may  be  90°  Fahr.  at  noon, 
and  40°  in  the  evening.  The  real  cause  of  the  elevation  or 
depression  measured,  is  to  be  found  in  the  more  or  less  per- 
fect saturation  of  the  atmosphere  in  which  the  experiments 
were  conducted.  There  is,  however,  a  great  difference  be- 
tween the  amount  of  heat  measured  by  M.  Dutrochet  and 
myself;  but  whatever  may  be  the  cause  of  the  discrepancy,  the 
measures  given  in  the  tables  are  certainly  free  from  error, 
since  most  of  them  were  authenticated  by  the  simultaneous 
examination  of  my  friends  at  Hampden  Sidney  College. 

We  are  much  more  concerned  by  the  apparent  anomalies 
exhibited  by  Nature.    Why  are  not  all  plants  destroyed  by 
frost?    Why  do  not  tubers,  bulbs,  &c.  perish  during  winter? 
For  if  there  be  no  specific  heat  in  these  organized  substances, 
their  fluids  should  freeze  and  thereby  produce  disorganiza- 
tion.    In  reply  to  this  we  remark,  that  the  fluids  of  vegetables 
congeal  at  temperatures  below  the  freezing  point  of  water  in 
consequence  of  the  presence  of  mucilage  and  acids,  &c.  Again, 
the  degree  of  succulence  of  the  plant  and  strength  of  the 
tissues,  as  well  as  their  non-conducting  nature,  must  not  be 
lost  sight  of.     It  is  remarkable  that  all  northern  evergreens 
have  more  or  less  coriaceous  leaves.     The  vegetation  of  coun- 
tries invaded  by  cold  is  hardier  than  that  found  in  the  tropics; 
in  the  former  localities  the  majority  of  plants  are  annuals  or 
perennials,  or  trees  which  cast  their  leaves ;  whilst  in  the  south 
evergreen  trees  abound  which  are  incapable  of  enduring  ex- 
posure to  one  frost.    Our  trees  are  often  found  with  their  sap 
frozen  without  the  texture  being  destroyed ;  and  in  the  Annates 
de  Chem.  et  de  Phys.,  torn.  xv.  p.  84,  there  is  an  account  of  a 
parcel  of  young  trees  which  were  kept  in  a  frozen  state  for 
twenty-one  months  and  yet  finally  vegetated  when  gradually 
thawed  and  planted  out,  showing  conclusively  that  the  woody 
fibre  resisted  the  disruptive  force  of  the  expanding  water  when 
in  the  act  of  freezing.     The  non-conducting  nature  of  the 
bark  and  wood  is  another  powerful  protection  ;  we  witnessed 
a  poplar  tree  cut  down  in  the  depth  of  winter  ;  on  the  northern 
side  of  the  trunk  the  wood  was  quite  dry  and  the  sap  probably 
frozen,  whilst  on  the  southern  exposure  the  sap  was  fluid : 
this  fact  proves  the  necessity  of  paying  every  attention  to  the 
exposure  of  trees  which  are  transplanted  in  the  winter,  espe- 
cially evergreens. 

Many  roots,  tubers,  bulbs,  &c.  may  be  exposed  with  appa- 
rent impunity  during  winter,  but  if  we  examine  the  conditions 
necessary  to  secure  them,  it  is  found  that  they  must  be  either 
covered  with  soil  or  are  naturally  of  a  dry  and  amylaceous 


Notices  of  the  Labours  of  Continental  Chemists.         15 

nature.  The  protective  power  of  a  slight  covering  of  soil  or 
vegetable  matter  is  extraordinary;  some  potatoes  were  covered 
with  about  two  inches  of  earth  and  others  left  exposed  on  the 
surface  of  the  ground  at  the  same  spot  of  the  garden  in  No- 
vember ;  a  frost  occurred  at  night,  the  thermometer  sinking 
to  28°  Fahr.,  and  it  was  found  that  all  the  uncovered  potatoes 
were  frozen,  their  cellular  tissue  being  broken  up ;  whereas 
the  buried  specimens  were  entirely  free  from  the  action  of  the 
cold.  The  temperatjire  of  springs  is  worthy  of  notice  as  a 
proof  of  the  non-conducting  nature  of  the  earth,  whereby  it 
is  well  calculated  to  preserve  organic  structures  from  the  ef- 
fects of  frost. 

These  conjectures  are  advanced  not  as  satisfactory  argu- 
ments against  the  apparent  objections  detailed,  but  only  as 
throwing  out  hints  for  future  researches.  These  objections 
do  not  invalidate  our  measures,  for  they  are  demonstrable. 
The  deductions  may  be  in  error,  but  we  are  content  to  offer 
the  experiments  as  a  contribution  to  the  science  of  botany. 

D.  P.  G. 

II.    Notices  of  the  Results  of  the  Labours  of  Continental  Che- 
mists.   By  Messrs.  W.  Francis  and  H.  Croft. 

[Continued  from  vol.  xx.  p.  225.] 

On  the  Oils  of  Fennel,  Anise,  and  Star-anise  (Illicium  anisatum). 

]\/T  CAHOURS  has  examined  the  stearopten  of  these  three 
-r  A  •  oils,  and  has  found  them  to  be  perfectly  identical ;  the 
substance  used  for  the  experiments  was  generally  made  from 
the  oil  of  anise,  because  from  this  oil  it  can  be  obtained  in 
larger  quantities  than  from  either  of  the  others.  The  solid 
oil  can  be  very  easily  obtained  pure  by  expression  and  cry- 
stallization in  alcohol.  It  crystallizes  in  white  shining  leaves. 
Its  specific  gravity  is  nearly  equal  to  that  of  water.  It  is  pul- 
verisable  at  0°,  melts  at  18°  C,  and  boils  at  222°.  On  being 
converted  into  vapour  it  appears  to  suffer  some  change,  so 
that  the  observed  density  of  the  vapour  does  not  agree  with 
that  calculated  from  the  formula.  In  a  solid  state  it  is  not 
changed  by  exposure  to  the  air,  but  if  kept  fluid  for  a  length 
of  time  it  is  converted  into  a  resin  ;  chlorine  and  bromine  act 
violently  on  it;  alkalies  have  no  action  except  when  employed 
in  the  manner  proposed  by  Dumas  and  Stass,  in  which  case 
an  acid  product  is  obtained.  Strong  acids,  as  the  sulphuric, 
phosphoric  acids,  &c,  change  it  into  an  isomeric  body.  The 
atomic  weight  of  the  solid  anise  oil  was  determined  by  mea- 
suring the  quantity  of  hydrochloric  acid  absorbed  by  it  The 
formula  is  C20  H24  O2. 


16        Notices  of  the  Labours  of  Continental  Chemists. 

Bromide  of  anisal  {BromanisaT). — Bromine  acts  violently  on 
the  solid  oil,  hydrobromic  acid  is  evolved ;  on  allowing  the 
fluid  mass  to  stand  for  some  time  it  partly  solidifies ;  small 
portions  of  aether  extract  an  oil  which  contains  bromine,  and 
the  solid  substance  may  be  purified  by  solution  in  boiling  aether 
and  pressing  between  bibulous  paper.  It  is  colourless,  forms 
voluminous  crystals,  insoluble  in  water,  somewhat  soluble  in 
alcohol,  and  more  so  in  aether.  It  is  decomposed  at  a  tempera- 
ture above  100°.    Formula  is  C20  H18  Br6'  O2. 

The  action  of  chlorine  is  more  complex  ;  according  to  the 
length  of  time  the  chlorine  has  acted  different  products  are 
formed,  none  of  which  crystallize,  and  whose  purity  therefore 
cannot  be  relied  on.  Once  a  substance  was  obtained  with  the 
formula  C20  H18  CI6'  O2.  The  next  product  is  C20  H15  CP  O2. 
Both  bodies  are  decomposed  by  distillation. 

Sulphuric  and  phosphoric  acids  and  some  anhydrous  chlo- 
rides, as  those  of  tin  and  antimony,  convert  the  solid  oil  into  a 
white  crystalline  substance,  soluble  in  sulphuric  acid  with  a 
red  colour ;  it  has  exactly  the  same  composition  as  the  solid 
oil,  viz.  C20  H24  O2;  Cahours  calls  it  Anisoin. 

By  the  action  of  nitric  acid  of  23-24-°  Beaume  a  new  cry- 
stallizable  acid  is  obtained,  which  has  been  mentioned  in  one 
of  our  former  reports. 

Anisic  acid. — The  rough  impure  acid  may  be  dissolved  in 
ammonia,  the  salt  recrystallized  several  times,  and  from  the 
insoluble  lead  salt  the  pure  acid  may  be  obtained.  The  acid 
crystallizes  in  long  needles,  sparingly  soluble  in  cold  water, 
but  much  more  so  in  boiling  water ;  easily  soluble  in  alcohol 
and  aether. 

It  can  be  volatilized  without  decomposition,  and  forms  soluble 
salts  with  the  alkalies  and  earths.  The  lead  and  silver  salts 
are  soluble  in  hot  water.  The  acid  precipitates  sesquioxide  of 
iron,  like  benzoic  and  cinnamic  acids.  Formula  is  C16  H14  O6. 
The  aether  may  be  prepared  by  passing  hydrochloric  acid  into 
an  alcoholic  solution  of  anisic  acid. 

By  heating-  anisic  acid  with  an  excess  of  baryta  a  fluid  sub- 
stance, anisoX  is  obtained  similar  to  Mitscherlich's  benzin,  in- 
asmuch as  it  seems  to  form  analogous  compounds ;  it  differs, 
however,  in  so  far  that  it  contains  oxygen,  its  formula  being 
C14  H14  O2. 

Note.— [The  confusion  in  chemical  nomenclature  seems 
nearly  to  have  reached  a  climax.  Berzelius  has  proposed 
some  excellent  rules  for  the  terminations  of  names,  but  they 
have  unfortunately  been  but  little  attended  to.  Mitscherlich's 
discovery  of  benzin  paved  the  way  to  that  of  many  similar  sub- 
stances.    He  called  this  substance,  C12  H12  benzin.    Liebig 


Action  of  Chromic  Acid  on  Volatile  Oils.  1 7 

calls  it  benzol.  A  similar  substance  obtained  by  Gerhardt  and 
Cahours  from  cinnamicacid,  C16H16,  is  called  cinnamen,  that 
from  cuminic  acid,  cumen.  Simoux  and  Marchand  call  cin- 
namen  cinnamomin.  Cahours  calls  the  above  substance  anisol, 
it  being  prepared  exactly  like  benzol  (benzin). — H.  C] 

Anisonitric  acid  is  formed  by  boiling  the  anise  oil  with  strong 
nitric  acid  until  the  oily  substance  first  produced  is  redis- 
solved.  The  acid  solution  is  precipitated  by  water  and  the 
substance  well  washed,  dissolved  in  ammonia  and  its  salt  cry- 
stallized several  times,  out  of  it  the  pure  acid  may  be  obtained. 
It  is  yellowish  white,  not  very  soluble  even  in  warm  water, 
and  crystallizes  out  of  its  hot  solution  in  small  acicular  crystals, 
tolerably  soluble  in  alcohol.  Forms  insoluble  salts  with  lead 
and  silver.  It  cannot  be  sublimed  unchanged.  Formula  for 
the  free  acid  C16  H12  N2  O10;  one  atom  of  water  is  driven  out 
when  it  is  combined  with  oxide  of  silver,  the  formula  of  that 
salt  being  C16  H10  N209,  Ag  O  (the  crystallized  aether  of  this 
acid  has  been  noticed  by  Mitscherlich).  By  the  action  of 
fuming  nitric  acid  on  the  solid  anise  oil  a  resinous  substance  is 
obtained,  nitranisid;  its  probable  formula  is  C20  H20  N4  O10  (?). 
Treated  with  caustic  alkalies  it  evolves  ammonia  and  is  con- 
verted into  melasinic  acid.  Oil  of  bitter  fennel  (fenonilamer) 
appears  to  consist  of  two  oils,  one  solid  having  the  same  com/- 
position  as  that  of  anise-oil,  and  a  volatile  one  having  the  same 
constitution  as  the  oil  of  lemon  and  turpentine. 

If  a  stream  of  binoxide  of  nitrogen  be  passed  into  this  latter 
oil,  it  becomes  thick  and  opake,and  alcohol  of  0*80  causes  a 
white  silky  precipitate  which  must  be  washed  with  alcohol.  By 
a  gentle  heat  this  substance  becomes  yellow  and  is  easily  de- 
composed. Somewhat  soluble  in  absolute  alcohol,  more  so  in 
aether,  soluble  in  concentrated  solution  of  alkali,  and  is  preci- 
pitated again  by  acids.  Formula  C15  H24  N4  O4. — {Annales  de 
Chem.  ft  de  Phys.,  Juillet  1841,  p.  274.) 

Action  of  Chromic  Acid  on  several  Volatile  Oils. 

Persoz  has  examined  the  products  obtained  by  treating 
aethereal  oils  with  a  mixture  of  bichromate  of  potash,  sul- 
phuric acid  and  water.  From  the  oils  of  anise,  star-anise 
(anise  etoilee)  and  fennel,  acetic  acid  and  an  insoluble  pro- 
duct consisting  of  two  acids,  were  produced.  These  acids 
Persoz  calls  Umbellic  and  Badianic  acids.  The  umbellic  acid 
is  little  soluble  in  cold  water,  more  in  hot,  soluble  in  alcohol, 
very  little  in  aether;  and  can  thus  be  separated  from  badianic 
acid ;  with  concentrated  nitric  acid  it  forms  an  acid  similar  to 
the  cinnamonitric.  In  its  salts  it  resembles  the  benzoates.  It 
melts  at  1 75°  or  1 80°  C,  boils  at  275°  to  280°.    [This  umbellic 

Phil.  Mag.  S.  3.  Vol.  21.  No.  135.  July  1842.  C 


18  Notices  of  the  Labours  of  Continental  Chemists. 

acid  seems  to  differ  from  the  anisic  solely  in  being  insoluble 
in  aether;,  it  would  be  worth  while  to  examine  this  point  further. 
Both  acids  are  formed  equally  well  outof  all  three  oils. — H.  C] 

Badianic  acid  is  more  soluble  in  water. 

By  the  action  of  chromic  acid  on  Roman  carraway  oil, 
Persoz  obtained  two  acids,  cyminic  and  cumino-cyminic.  The 
former  melts  at  115°;  it  is  tasteless,  little  soluble  in  cold  water, 
easily  in  alcohol  and  aether.  The  latter  is  insoluble  in  all 
three  liquids.  It  is  not  decomposed  by  boiling  with  strong 
sulphuric  acid.  From  some  other  oils  new  acids  have  been 
obtained,  but  as  both  they  and  those  above  have  not  yet  been 
fully  described,  it  will  be  better  to  defer  any  further  report 
upon  them  for  the  present.  Oil  of  cinnamon  gives  acetic  and 
benzoic  acids,  and  according  to  Marchand  a  considerable 
quantity  of  hydruret  of  benzoyl.  It  must  be  remarked  that  in 
these  reactions  acetic  acid  is  always  formed. — (Comptes  Rendus, 
torn.  xiii.  No.  8.  p.  433.) 

Action  of  Hydrate  of  Potassa  on  Hydrobenzamid. 

Rochleder  finds  the  formula  for  hydrobenzamid  to  be 
C21  H18  N2;  when  fused  with  the  hydrate  it  becomes  yellow, 
at  last  black,  and  ammonia  is  evolved  ;  the  residual  mass  is 
washed  with  water.  The  washed  powder  is  yellow,  fusible  at 
a  gentle  heat,  decomposed  at  a  higher  temperature,  partly 
soluble  in  alcohol  and  aether:  it  consists  of  three  bodies;  the 
first  is  found  in  small  quantities  at  the  commencement  of  the 
operation  ;  it  is  a  yellow  oil  soluble  in  alcohol,  but  has  not  been 
further  examined :  the  second  is  soluble  in  alcohol,  white  and 
crystalline ;  the  author  calls  itbenzostilbin :  the  third,  benzolon, 
is  also  white  and  crystalline,  but  insoluble  in  alcohol ;  it  is 
formed  during  the  latter  part  of  the  operation. 

Benzostilbin  when  freed  from  oil  is  not  very  soluble  in  al- 
cohol, soluble  in  aether,  by  means  of  which  it  can  be  obtained  in 
large  crystals.  Melts  at  244'5°  C,  and  at  a  higher  temperature 
sublimes,  but  not  unchanged ;  soluble  in  concentrated  sul- 
phuric acid  with  blood-red  colour.  Not  decomposed  by 
boiling  with  caustic  potassa.     Formula  C31  H22  O2. 

Benzolon  is  purified  by  solution  in  warm  sulphuric  acid 
and  precipitation  out  of  the  red  solution  by  alcohol.  It  is 
crystalline,  insoluble  in  water  and  alcohol,  melts  at  248°  C, 
sublimes  almost  unchanged.  Decomposed  by  fuming  nitric 
acid.  Formula  C11  H8  O1,  or  benzon  minus  benzin  (benzol.) 
— {Ann.  der  Chem.  und  Pharm.,  vol.  xli.  p.  89.) 

On  the  Salts  q/Uvic  (Racemic)  Acid. 
Uvic  acid  is  monobasic  according  to  Fresenius,  and  this  is 
its  principal  point  of  difference  from  tartaric  acid.     In  the 


Salts  of  Uvic  Acid. — Nicotin.  19 

crystallized  state  it  contains  two  atoms  of  water;  only  one  can 
be  driven  out  by  heat,  the  other  is  basic.  The  neutral  salts 
of  the  alkalies  are  easily  soluble  and  crystalline,  form  acid 
salts,  but  the  fixed  alkalies  do  not  form  together  double  salts. 
The  salts  of  the  alkaline  earths  are  difficultly  soluble,  form 
no  double  salts,  but  this  is  found  to  be  the  case  with  those 
salts  of  the  magnesian  series  which  contain  halhydrate  water. 

Ammonia  salt ...     Uv  +  N2  H8  O.  _ 

Acid  salt Uv.  N2  H8  0  +  Uv.  H2  O. 

Potassa  salt UvKO-f-2aq.  ("Compounds  similar  to 

Acidsalt £K<HU*.H'0,J  aTffS&Ett 

Soda  salt Uv  Na  O.  L  the  French  may  be  ob- 

Acid  salt UvNa  O  +  Uv  H20+2aq.  tained- 

Uvate  soda "]  

+  ^UvNaO  +  Uv.N2H80  +  2aq. 

Uvate  ammonia  J  

Baryta  salt U v  Ba  O  +  2 }  aq. 

Strontia  salt     ...      UvSrO  +  4aq. 

Lime  salt UvCaO  +  4aq. 

Magnesia  salt ...     Uv  Mg  O  +  5  aq. 
Manganese  salt       Uv  Mn  O  +  aq. 

Nickel  salt  UvNiO  +  5aq. 

Copper  salt UvCuO  +  2aq. 

&c.  &c.  &c. — {Ann.  der  Chan,  und  Pharm.,  vol.  xli.) 

Nicotin. 

Ortigosa  gives  the  following  statements  with  regard  to 
nicotin.  It  is  colourless,  transparent,  smells  disagreeably  of 
tobacco,  distils  perfectly  at  100°  C,  and  generally  leaves  a 
resin  behind  which  is  soluble  in  alcohol.  With  a  small  quan- 
tity of  water  it  gives  a  clear  solution,  which  is  rendered  opake 
by  the  addition  of  more  water.  Soluble  in  alcohol  and  aether, 
the  solutions  react  alkaline. 

Its  neutral  solution  in  hydrochloric  acid  gives  a  crystal- 
line precipitate  with  bichloride  of  platinum.  Formula  C10 
H18  N2  CI6'  Ft,  consequently  pure  nicotin  is  C10  H16  N2. 
Nicotin  also  combines  with  chloride  of  mercury ;  the  com- 
pound is  formed  by  mixing  the  solutions.  The  white  cry- 
stalline precipitate  is  insoluble  in  water  and  aether,  difficultly 
in  alcohol,  melts  under  100°  C,  and  becomes  yellowish.  Com- 
position C10  H16  N2  +  Hg  CI2.— {Ann.  Chcm.  u.  Pharm.,  xli.) 
On  a  new  Acid  of  Sulphur. 

Langlois  some  time  since  published  a  method  for  obtaining 
hyposulphurous  acid.    He  prepared  the  potassa  salt  by  digest- 

C2 


20  Notices  of  the  Labours  of  Continental  Chemists. 

ing  bisulphite  of  potassa  with  sulphur,  and  precipitating  the 
alkali  by  means  of  hy perchloric  acid.  The  acid  thus  separated 
is,  however,  not  hyposulphurous  but  a  new  acid.  A  concen- 
trated solution  of  the  bisulphite  is  digested  with  flowers  of 
sulphur,  but  without  allowing  the  mixture  to  boil ;  sulphurous 
acid  is  evolved,  sulphuric  acid  generated,  and  the  solution  ac- 
quires a  yellow  colour,  which,  however,  soon  vanishes.  The 
crystals  which  separate  on  cooling  are  dissolved  in  a  very 
small  quantity  of  water  and  purified.  The  salt  so  obtained  is 
not  decomposed  by  hydrochloric  acid,  is  not  changed  by  ex- 
posure to  the  air,  and  when  heated  leaves  neutral  sulphate  of 
potassa :  100  parts  of  the  salt  gave  23*76  sulphurous  acid, 
1 1  -88  sulphur,  and  64*36  sulphate  of  potassa.  The  constitu- 
tion of  the  acid  is  therefore  3  S  +  5  O.  Langlois  calls  it  "  acide 
hyposulfurique  sulfure  "  (Sulpho-hyposulphurous  acid). 

"  The  new  salt  crystallizes  in  four-sided  prisms  with  two  ter- 
minal faces,  tastes  somewhat  saline  and  bitter,  is  very  soluble 
in  water,  insoluble  in  alcohol ;  the  solution  is  decomposed  by 
sulphuric  and  nitric  acids  when  heat  is  employed,  sulphur  and 
sulphurous  or  nitrous  acids  are  produced.  Hydrochloric, 
chloric  and  iodic  acid  are  without  action.  Hyperchloric  acid 
isolates  the  new  acid.  It  does  not  precipitate  the  salts  of  lime, 
strontia,  baryta,  magnesia,  alumina,  iron,  zinc,  nickel,  cobalt, 
uranium,  copper  and  lead ;  from  the  salts  of  dinoxide  of  mer- 
cury it  precipitates  the  sulphuret,  with  salts  of  the  oxide  it  gives 
a  white  precipitate  of  sulphate  of  the  dinoxide ;  it  precipitates 
silver  salts  yellowish-white,  which  soon  changes  to  black. 

The  free  acid  possesses  almost  all  the  characters  of  hypo- 
sulphurous  acid ;  it  is  rapidly  decomposed  by  chloric  and  iodic 
acid. — [Ann.  der  Chem.  und  Pharm.,  si.  p.  102-110.) 

On  some  double  Hyposulphites. 

Lenz  prepared  these  salts  by  means  of  the  hyposulphite  of 
soda,  for  the  preparation  of  which  Liebig  proposes  the  follow- 
ing method.  A  solution  of  sulphurous  acid  or  acid  sulphite 
of  soda  is  saturated  with  carbonate  of  soda,  and  a  saturated 
solution  of  sulphur  in  caustic  soda  added  until  a  tinge  of  co- 
lour shows  that  there  is  some  sulphuret  of  sodium  undecom- 
posed.     The  filtered  solution  is  evaporated,  &c. 

The  hyposulphite  of  soda  forms  two  double  salts  with-  oxide 
of  silver.  They  may  be  obtained  by  means  of  either  the  chlo- 
ride or  the  nitrate  of  silver ;  chloride  of  silver  is  added  to  a 
saturated  solution  of  the  hyposulphite  until  the  solution  begins 
to  be  opake,  it  is  then  filtered  and  precipitated  by  alcohol. 
The  precipitate,  which  is  the  one  double  salt  soluble  in  water, 
is  thus  obtained  pure  in  shining  scales,  it  is  edulcorated  with 


On  some  double  Hyposulphites.  21 

alcohol  and  dried  in  vacuo.  The  second  salt  is  difficult  to 
obtain  pure  by  this  method.  In  the  second  manner  it  may 
be  obtained  by  adding  to  a  solution  of  the  hyposulphite  per- 
fectly neutral  nitrate  of  silver  until  the  precipitate  becomes 
constant.  The  salt  is  at  first  flocculent,  it  afterwards  becomes 
crystalline,  and  must  be  washed  out  with  water. 

First  salt. — Has  a  sweet  taste,  is  not  changed  by  exposure 
to  light  and  air,  but  becomes  coloured  at  a  temperature  below 
100°  C.  Its  aqueous  solution  is  decomposed  by  long  boiling, 
sulphuret  of  silver  is  deposited;  it  is  easily  soluble  in  ammo- 
nia, not  perfectly  insoluble  in  alcohol.  Hydrochloric  acid 
affects  it  slowly;  when  boiled  it  produces  a  black  precipitate, 
from  which  ammonia  extracts  chloride  of  silver.     Its  formula 

is  Ag  S '+  2  Na  S  -f  2  aq. 

The  second  salt  is  difficultly  soluble  in  water,  soluble  in 
ammonia  and  excess  of  hyposulphite  of  soda  (forming  the 
above  salt) ;  it  is  a  dirty  white  crystalline  powder,  which  be- 
comes black  by  boiling  with  water,  and  becomes  gradually  co- 
loured in  the  air.     Its  formula  is  Ag  S  +  Na  S  +  aq. 

Plumbo-hyposulphite  of  Soda  is  best  prepared  by  means  of 
acetate  of  lead,  like  the  first  argento-hyposulphite.  It  becomes 
crystalline,  is  white,  easily  soluble  in  acetate  of  soda,  little  in 

water,  difficultly  in  alcohol.  Formula  is  Pb  S  +  2  Na  S ;  it 
is  therefore  anhydrous. 

Cupro- hyposulphite  of  Soda. — On  mixing  a  solution  of  the 
hyposulphite  of  soda  with  an  excess  of  sulphate  of  copper,  a 
yellow  crystalline  precipitate  is  formed ;  this  must  be  quickly 
filtered  and  washed  with  very  dilute  acetic  acid,  and  then 
dried  in  vacuo^  for  it  easily  becomes  brown  and  is  decomposed. 
It  is  not  at  all  soluble  in  alcohol,  difficultly  in  water,  easily  in 
hyposulphite  of  soda.  Out  of  this  solution  alcohol  precipi- 
tates a  salt  easily  soluble  in  water.  It  dissolves  in  ammonia 
with  a  brownish  vellow  colour,  which  in  the  «air  changes  to 
blue ;  it  is  consequently  a  salt  of  the  dinoxide.  It  is  decom- 
posed immediately  by  concentrated  sulphuric  acid,  and  by 
dilute  when  boiled ;  sulphurous  acid  is  evolved  and  sulphuret 
of  copper  precipitated,  the  solution  contains  oxide;  when  the 
decomposition  is  effected  by  means  of  hydrochloric  acid  the 

solution  contains  dinoxide.  Formula  3  Cu  S  +  2  Na  S-f-5  aq. 
By  mixing  solutions  of  the  hyposulphite  and  of  a  neutral 
salt  of  sesquioxide  of  iron,  a  deep  black  red  liquid  is  obtained, 
which  speedily  decolorizes  and  then  contains  protoxide. — 
(Ann.  der  Chem.  und  Phar?n.,  vol.  xl.  p.  94-101.) 


[     22     ]        . 

III.  Further  Remarks  on  Fernel's  Measure  of  a  Degree,  in 
Reply  to  Professor  De  Morgan's  Letter  in  the  Number  for 
May.    By  Thomas  Galloway,  A.M.,  F.R.S. 

To  the  Editors  of  the  Philosophical  Magazine  and  Journal. 

Gentlemen, 
OO  long  as  the  argument  relative  to  the  length  of  Fernel's 
degree  of  the  meridian  turned  upon  a  standard  of  measure 
derived  from  the  human  body,  or  the  length  of  a  man's  walking 
pace,  I  saw  little  reason  for  adding  any  thing  to  my  former 
communication,  being  satisfied  that  a  result  expressed  in  terms 
of  such  a  standard  would  bear  any  interpretation  (at  least 
within  wider  limits  than  would  include  the  differences  under, 
discussion)  that  any  one  might  choose  to  give  it ;  but  the  new 
evidence  which  has  been  produced  by  Prof.  De  Morgan  in  your 
Number  for  May,  changes  entirely  the  state  of  the  question. 

The  conclusion  at  which  Mr.  De  Morgan  has  ultimately 
arrived  is  founded  on  two  assumptions :  first,  that  the  diagram 
or  figure  in  the  Monalosphccrium  is,  or  originally  was,  a  copy 
of  a  foot-length  as  laid  down  on  a  scale ;  and  secondly,  that 
Fernel  used  the  same  or  an  equivalent  foot  in  measuring  the 
diameter  of  the  wheel  of  the  vehicle  in  which  he  travelled  from 
Amiens  (or  wherever  his  station  was)  to  Paris.  With  re- 
spect to  the  second  assumption  there  is  no  evidence  what- 
ever ;  and  on  looking  at  the  copy  of  Fernel's  work  in  the  British 
Museum,  I  think  there  are  strong  reasons  for  doubting  the  ac- 
curacy of  the  first.  Fernel  does  not  say  that  his  diagram  was 
intended  to  define  the  length  of  the  geometrical  foot,  or  that  it 
corresponded  in  dimension  with  any  actual  scale ;  on  the  con- 
trary, there  is  no  allusion  to  it  in  the  text  at  all,  and  unless  the 
title  printed  under  it,  "  Figuratio  pedis  geometrici,"  beheld 
to  have  reference  to  magnitude,  there  is  nothing  to  lead  us  to 
infer  that  he  had  any  other  object  in  view  than  simply  to  re- 
present by  a  diagram  the  divisions  which  should  be  cut  on  a 
measuring  rod.  The  pj)rt  of  the  work  in  which  the  passage 
occurs  is  a  treatise  on  Mensuration  ;  and  in  describing  the  mea- 
suring rod  he  remarks  that  it  should  be  selected  with  great 
pains,  "  omni  molimine"  (referring  probably  to  the  accuracy 
of  the  division),  and  enriched  with  a  diversity  of  measures, 
"  mensurarum  diversitate  locupletata ; "  that  it  should  be  five 
feet  in  length,  and  marked  with  the  divisions  expressed  in  the 
following  table,  viz.  four  grains  =  a  digit,  four  digits  =  a 
palm,  four  palms  =  a  foot,  five  feet  =a  a  pace.  The  diagram 
shows  all  those  divisions  of  the  foot ;  but  there  seems  to  me 
no  more  reason  for  supposing  that  they  were  intended  to  be 


Mr.  Galloway's  Remarks  on  Fernel's  Measure  of  a  Degree.  23 

of  their  proper  length,  than  there  is  for  supposing  that  the 
drawings  from  the  human  body  with  which  some  of  the  old 
authors  illustrated  their  measures,  were  intended  to  be  of  the 
natural  size,  which  they  manifestly  are  not.  The  figure  is  a 
line  marked  on  the  margin  of  the  page,  extending  as  high  as 
the  head-line  at  the  top,  and  a  little  below  the  letter-press  at 
the  foot ;  and  suggests  the  idea  of  its  having  been  adapted 
by  the  printer  to  the  length  of  the  page,  or  made  as  long  as 
possible  for  the  purpose  of  showing  the  small  divisions. 

It  should  be  kept  in  mind  that  the  work  in  which  the  dia- 
gram is  found  is  not  that  in  which  Fernel's  operation  for  mea- 
suring the  degree  is  described,  nor  does  it  contain  any  allusion 
to  that  operation,  which  was  probably  not  executed  when  the 
work  was  printed.  Neither  is  there  in  the  Cosmotheoria  any 
allusion  to  this  figure. 

Supposing,  however,  the  fact  to  be  as  Mr.  De  Morgan  assumes, 
how  are  we  to  reconcile  the  result  with  the  reasoning  in  his 
previous  papers  respecting  the  geometrical  pace  and  the  Italian 
mile?  In  his  first  letter  he  stated  the  Italian  mile  to  be  1628 
English  yards,  or,  according  to  Dr.  Bernard,  1667  yards,  the 
former  statementgiving  Fernel's  degree  equal  to  about  63  statute 
miles,  and  the  latter  to  641 ;  and  in  his  second  letter  he  con- 
firms this  result  by  arguments  which  he  considers  to  be  deci- 
sive of  die  question.  But  when  the  actual  measure,  or  what 
is  assumed  to  be  such,  is  produced,  it  turns  out  that  the  true 
length  is  only  53  miles  and  three  quarters.  The  error  was 
therefore  between  a  fifth  and  a  sixth  of  the  whole  quantity. 
Mr.  De  Morgan  himself  appears  to  feel  this  difficulty,  and 
observes  that  the  difference  cannot  be  easily  explained  unless 
we  adopt  a  surmise  of  Paucton,  that  the  geometrical  pace  was 
4^  Roman  feet.  What  weight  may  be  due  to  this  surmise 
I  cannot  pretend  to  say,  but  the  discrepancy  seems  to  afford 
a  pretty  conclusive  proof  of  the  accuracy  of  the  position  main- 
tained in  my  former  letter,  namely,  that  the  Italian  mile  and 
geometrical  pace  were  vague  and  indefinite  terms,  having  no 
certain  meaning  unless  defined  with  reference  to  some  standard 
foot,  and  that  therefore  the  use  of  them  by  Fernel  afforded 
no  presumption  against  the  supposition  of  Pi  card,  that  his 
measure  was  given  in  Paris  feet.  If  Paucton  surmises  that 
the  geometrical  pace  was  4£  Roman  feet,  he  also  surmises  that 
it  was  greater  than  5  Roman  feet  (p.  179);  but  he  likewise 
tells  us  that  the  idea  of  the  geometrical  pace  has  been  lost  for 
ages. 

According  to  Mr.  De  Morgan's  hypothesis  Fernel's  68*096 
Italian  miles  contained  3,404,800  English  inches,  and  conse- 
quently a  single  mile  was  equivalent  to  1389  English  yards, 


24<  Mr.  Galloway's  Remarks  on  FernePs  Measure  of  a  Degree. 

which  is  278  yards  shorter  than  the  Italian  mile  of  Dr.  Ber- 
nard, and  225  yards  shorter  than  the  old  Roman  mile,  with 
which  jVIr.  De  Morgan  states  (I  think  on  good  grounds)  that 
the  Italian  mile  was  commonly  though  vaguely  supposed  iden- 
tical. The  difference  is  so  great,  and  the  result  so  much  at 
variance  with  all  the  other  authorities  which  have  been  pro- 
duced, and  which  concur  in  giving  the  Italian  mile  longer  than 
the  Roman  mile,  that  if  we  admit  the  hypothesis  we  are  driven 
to  the  improbable  conclusion  that  Fernel,  without  intimation, 
laid  down  an  arbitrary  foot  for  himself,  thereby  rendering  his 
statements  unintelligible  or  deceptive. 

There  is  another  statement  of  Fernel's,  which  though  of  no 
value  towards  giving  the  exact  length  of  his  degree,  may 
perhaps  go  for  something  when  the  question  turns  upon  a 
difference  of  16  miles  in  70.  He  states  that  the  northern 
extremity  of  his  arc  was  reckoned  by  the  country-people  to 
be  25  leagues  distant  from  Paris.  Now  it  is  not  here  ma- 
terial to  inquire  what  the  length  of  the  league  was.  We 
know  from  the  difference  of  latitudes  that  the  distance  in  a 
straight  line  was  somewhere  about  70  English  miles,  and  it 
cannot  be  supposed  that  the  vulgar  estimate  was  in  error  to  the 
extent  of  anything  like  16  miles.  But  as  Fernel  manifestly 
supposes  his  own  determination  was  not  at  variance  with  the 
vulgar  estimate,  it  is  difficult  to  believe  that  he  gave  his  re- 
sult in  terms  of  a  scale  by  which  the  reputed  distance  must 
have  been  reduced  nearly  a  fourth  part.  Amiens,  from  which 
it  has  generally  been  supposed  he  measured,  is  75  miles  from 
Paris  by  the  road. 

I  may  also  add,  that  if  the  hypothesis  be  correct,  Fernel's 
notions  of  a  degree,  before  he  attempted  to  measure  it,  must 
have  been  very  extraordinary.  In  the  same  work  in  which  the 
figure  occurs  (Monalosphatrium,  p.  15)  there  is  a  proposition 
explaining  the  method  of  measuring  the  terrestrial  distances 
between  places,  in  which  he  directs  60  Italian  miles  to  be  al- 
'  lowed  for  each  degree  of  latitude,  and  one  mile  for  each  mi- 
nute, and  gives  some  examples  of  distances  socomputed.  But 
according  to  the  hypothesis  his  Italian  mile  of  5000  geome- 
trical feet  was  only  1389  English  yards,  whence  he  must  have 
supposed  the  degree  to  be  less  than  47|-  English  miles.  This 
is  surely  without  the  limits  of  credibility. 

It  is  proper,  however,  to  remark,  that  Riccioli,  in  his  Geo- 
graphia  Reformata,  lib.  ii.  c.  2,  mentions  Fernel's  diagram, 
and  gives  the  ratio  of  its  length  to  the  ancient  Roman  foot, 
whence  it  may  be  inferred  that  he  regarded  it  as  intended  for 
the  representation  of  an  absolute  measure ;  but  Riccioli  al- 
lows no  authority  either  to  the  figure  or  to  the  statements  of 


The  Rev.  D.  Williams  on  the  Cornish  Killas  25 

Fernel  respecting  the  length  of  the  geometrical  pace.  His 
words  are,  "  Neque  audiendus  est  Fernelius,  qui  lib.  i.  Cos- 
motheoriae  c.  i.  in  Schol.  ait  passus  5  hominis  mediocris  sta- 
turse  efficere  passus  6  geometricos,  et  parte  4  Praxis  Geome- 
tries pedem  geometricum  exponit  qui  ad  Romanum  Vespasi- 
anicum  est  ut  1030  ad  1200." 

On  the  grounds  above  stated, — the  total  absence  of  direct 
testimony  that  the  line  figured  in  the  Monalosphcerium  is  a 
copy  of  the  foot  used  by  Fernel,  and  the  improbability  of  the 
consequences  resulting  from  the  supposition, — I  think  we 
must  conclude  either  that  the  diagram  was  intended  for  nothing 
more  than  to  illustrate  the  description  of  the  measuring  rod, 
or  else  that  it  was  reduced  by  the  printer;  and  that  the  ques- 
tion as  to  the  true  length  of  Fernel's  degree  remains  as  doubt- 
ful as  ever.  At  the  same  time,  considering  the  great  uncer- 
tainty in  which  every  thing  connected  with  Fernel's  operation 
is  involved,  and  seeing  that  we  have  nothing  better  than  con- 
jectures to  reason  upon,  I  must  own  that  it  is  with  considerable 
diffidence  I  give  my  opinion  in  opposition  to  that  of  Professor 
De  Morgan,  who  has  evidently  bestowed  much  attention  on 
the  subject. 

I  remain,  Gentlemen,  faithfully  yours, 

May  12, 1842.  T.  Galloway. 

IV.  Supplementary  Notes  on  the  true  Position  in  the  "  Devonian 
System  "  of  the  Cornish  Killas.  By  the  Rev.  D.  Williams. 

To  the  Editors  of  the  Philosophical  Magazine  and  Journal. 
Gentlemen, 
TN  one  of  the  earliest  communications  I  had  the  honour  of 
■*-  submitting  to  the  public  through  the  medium  of  your  va- 
luable Journal,  I  pointed  out  both  by  text  and  section,  that 
the  Cornish  killas  was  the  last  or  newest  formation  in  "  the 
Devonian  System."  I  entertained  such  entire  confidence  in 
the  Chudleigh  Sections,  as  much  from  their  own  evidences 
as  from  the  crowd  of  contradictions  and  apparent  anomalies 
elsewhere  which  they  reconciled,  that  I  felt  no  hesitation  in 
committing  myself  absolutely  to  them,  from  the  conviction 
that  (as  Nature  could  not  deny  herself)  I  should  meet  with 
nothing  but  additional  confirmations  in  the  large  portion  of 
country  which  I  had  not  then  surveyed.  A  recent  excursion 
into  Devon  and  Cornwall  haying  furnished  me  with  some  im- 
portant structural  facts  in  addition  to  those  I  communicated 
in  your  Number  for  February  last,  I  request  permission  to 
detail  them  to  your  readers,  some  of  whom,  in  whose  conver- 
sion I  am  more  particularly  interested,  however  silent,  may 
not  yet  be  satisfied. 


26      The  Rev.  D.  Williams  on  the  true  Position  of  the 

Few  circumstances  in  my  short  geological  life  have  af- 
forded me  greater  delight  than  having  been  enabled  during 
that  excursion  to  determine  with  precision,  the  true  grade  in 
the  Coddon  Hill  series,  No.  8,  of  the  Ivy  Bridge  jasper  rock,  a 
rock  which  nearly  all  geologists  who  have  been  in  South  Devon 
can  hardly  have  failed  to  observe,  and  in  whose  nether  position 
as  regards  the  killas  country  on  the  south  of  it,  probably  as 
many  are  agreed ;  for  my  own  part  I  felt  perfectly  satisfied  that 
it  must  be  included  in  the  lower  culm  measures,  for  the  rea- 
sons mentioned  page  132.  No.  129  of  your  Journal;  but  I  also 
felt  that  I  might  not  be  able  to  convey  the  same  assurance  to 
the  minds  of  others.  I  apprehended  that  doubts  might  still  be 
entertained  that  it  was  some  peculiar  altered  rock,  or  tliat 
from  its  lower  terms  resting  on  the  granite,  that  volcanic  ag- 
gregate in  its  protrusion,  or  in  its  "  elevation-crater "  move- 
ment, might  have  brought  up  with  it  something  almost  as  fun- 
damental as  itself.  On  following  the  bed  of  the  East  Okement 
river  from  Oakhampton,  geographically  up,  but  geologically 
down  to  the  granite  of  Dartmoor,  I  passed  in  succession  the 
following  series,  all  dipping  north  at  a  mean  of  45°  to  50°. 

Black  slates. 

Olive  grit  beds,  and  fine 
foliated  gray  grit. 

Ivy  Bridge  jasper  grit 
Trap. 

Jasper  grit 
Trap. 

Jasper  grit,  passing 
into 

Granite. 

The  jasper  grit  up  the  East  Okement  is  as  identical  in  mi- 
neral type  and  composition  with  the  Ivy  Bridge  rock  as  it  is 
possible  for  any  two  specimens  from  any  continuous  bed  to 
be ;  it  is  a  strikingly  characterised  mineral  aggregate,  in  which 
I  have  nowhere  observed  a  vestige  of  organic  structure,  but 
at  each  locality  it  is  precisely  the  same  striped,  plated  and 
layered  compound,  a  coarse  ribbon  jasper,  possessing  the  same 
variegated  colours,  the  same  mineral  peculiarities,  and  the 
same  aberrations  from  a  mean  normal  type.  The  section  up  the 
East  Okement  presents  us  with  nothing  more  than  is  shown 
above  Ivy  Bridge,  viz.  the  same  peculiarly  marked  rock  resting 
upon  granite ;  but  let  us  ascend  the  West  Okement  up  to  the 
Posidonia  lime-rock  quarries  at  Meldon*,  and  we  at  once  ap- 
preciate the  force  and  value  of  the  East  Okement  and  Ivy 
Bridge  sections.  We  there  observe  the  following  descending 
series  dipping  north  at  about  50°. 

*  Spelt  Elmdon  on  the  Ordnance  sheet. 


Floriferous  schist  and  grit. 
Smoky  gray  schist. 


Cornish  Killas  in  the  Devonian  System.  27 


8 

l 

§ 

T3 
O 
U 


Black  slates,  rusly 
externally. 

Ivy  Bridge,  jasper  grit. 

Trap. 

Coddon  Hill  grit. 

Posidonia  limestone. 

Coddon  Hill  grit. 

Granite. 


s  r 

2       Olive-coloured  grits  and  shale. 
o  '   Smoky  gray  schist. 


m 

The  section  after  the  margin  of  the  river  up  to  the  Lime- 
rock  quarries  is  so  clear  and  unequivocal  in  its  details,  that 
nothing  is  left  to  inference  or  conjecture.  From  the  far  greater 
thickness  of  No.  8,  on  the  south,  and  from  other  facts  I  have 
collected,  I  have  now  no  doubt  that  this  jasper  grit  is  a  new 
term  introduced  into  the  Coddon  grit  series  on  the  south, 
which  is  altogether  absent  in  the  north  of  Devon  • ;  while  its 
position  above  the  Coddon  grit  and  its  Posidonia  limestones, 
each  in  a  totally  unaltered  condition,  assures  us  that  it  is  not 
a  metamorphic  rock. 

At  Tavistock  I  observed  that,  I  was  in  error  when  I  stated 
in  your  Journal,  No.  129,  p.  131,  that  on  "the  eastward  road, 
after  crossing^  the  Tavy  behind  the  Bedford  Arms,  the  culm 
schists  dipped  into  the  killas  hill,"  whereas  they  dip  to  the 
north  there,  or  outwards  from  Whitchurch  Down;  they  are 
however  at  the  base  of  that  hill ;  and  as  we  ascend  it  from  the 
first  turnpike  gate,  we  observe  them  to  incline  over  easily  to 
the  south,  and  to  be  overlaid  by  a  thick  accumulation  of  a 
dull  gray  and  pale  green  ash  which  passes  insensibly  into  a 
delicate  killas,  in  a  flat  position,  or  a  gently  and  long  undu- 
lating outline.  I  had  marked  this  low  southern  dip  of  the 
carbonaceous  schist  on  my  field  map,  and  from  its  small  scale, 
I  inadvertently  read  it  off  as  the  true  dip  along  the  south  mar- 
gin of  the  river,  less  than  a  furlong  distant. 

From  hence  I  went  to  South  Petherwin  near  Launceston, 
and  on  a  more  careful  examination  of  the  slates,  I  observed 
for  the  first  time  that  at  Does  House  the  killas  crosses  the 
little  brook  and  valley  and  ascends  and  flanks  the  carbonaceous 
slate  ridge  on  the  north,  both  dipping  together  to  the  south 
at  about  15°,  the  floriferous  or  culmy*beds  as  manifestly  un- 
derlying the  killas  as  any  one  rock  on  earth  underlies  another. 

*  In  a  prospectus  of  my  intended  publication  on  the  Geology  of  West 
Somerset,  Devon  and  Cornwall,  which  I  circulated  at  Plymouth  in  August 
last,  I  mentioned  this  rock  as  occurring  at  Landkey  Hill  near  Barnstaple; 
a  subsequent  examination  of  that  hill  in  November  last,  satisfied  me  that 
I  was  in  error  in  so  stating. 


28         The  Rev.  D.  Williams  on  the  Cornish  Killas. 


■South  Petherwin. 


.  Killas. 


Brook. 


Clymcnicn  Limestones. 


Does  House*. 


The  ascent  is  gradual  and  easy,  without  the  least  break  or  in- 
terval, and  from  the  circumstance  of  the  culm  slate  and  killas 
cuttings  being  old,  wayworn  and  dusty,  and  so  symmetrically 
packed  and  disposed,  I  had  pre- 
viously concluded  that  the  for- 
mer were  continued  down  to  the 
brook,  as  they  are  a  little  north 
of  Landlake  by  Bad  Ash,  about 
half  a  mile  to  the  eastward  ;.  on 
accosting  them  however  with  the 
hammer  foot  by  foot,  their  fresh- 
ly fractured  faces  quickly  un- 
deceived me,  and  left  me  in  no 
doubt  that  the  order  of  superpo- 
sition was  evidenced  here  with 
as  much  simplicity,  truth  and 
precision,  as  it  was  at  Boscastle, 
while  it  explained  in  the  most 
satisfactory  manner  the  imper- 
fect and  doubtful  section  at 
Landlake  near  at  hand,  which 
had  been  noticed  by  Mr.  Phil- 
lips in  his  Palaaozoic  Fossils,  pp. 
195  and  196,  and  by  myself  in 
your  Journal,  No.  129,  page  128. 
Immediately  adjoining  "  Does 
House"  on  the  west,  is  a  place 
marked  "  Tregaller"  on  the 
Ordnance  Map  ;  in  a  bye  lane 
near  this,  and  immediately  un- 
der the  letter  g,  I  fell  in  with  a 
quarry  of  the  Coddon  Hill  grit 
which  had  been  excavated  for 
the  roads:  its  beds  or  layers  in 
the  centre  of  the  quarry  have 
been  compressed  into  the  form 
of  two  pointed  Gothic  arches  ad- 
justed side  by  side,  from  which 
they  depart  by  an  easy  inclina- 
tion to  the  south  on  the  south 
side,  and  by  a  low  dip  to  the 
nort{i  on  the  north  side.  The 
quarry  is  on  the  summit  of  the 
ridge  and  apparently  in  its  axis. 


,..-_  Killas. 


—  Black  Culm  Slates. 


. .  Tregaller. 


Coddon  Hill  Grit. 


Does  House  is  about  a  furlong  east  of  the  line  of  section. 


Professor  Kelland's  Note  on  Fluid  Motion.  29 

I  went  from  hence  by  Petherwin  to  the  manganese  mine 
at  "  Bolathan,"  and  there  I  observed  the  pale  green  killas  had 
been  sunk  through  by  a  vertical  shaft  to  a  depth  of  twenty- 
five  feet  (as  I  was  informed)  down  to  the  Coddon  Hill  grit 
and  its  lode  of  manganese.  The  killas  here  is  unequivocally 
exposed  on  the  surface,  and  is  an  uninterrupted  continuation 
of  that  which  near  Petherwin  abounds  in  Clymeniae,  Gonia- 
tites,  Orthoceratites,  Trilobites,  Orthides,  &c.  &c. ;  and  if  the 
subordinate  grit  had  been  carted  to  the  spot  from  Coddon 
Hill  in  North  Devon,  or  from  St.  Stephen's  Down  near  Laun- 
ceston,  it  could  not  have  offered  closer  points  of  comparison 
and  agreement. 

The  lower  killas,  the  lowest  of  the  threefold  division  into 
which  that  great  member  of  the  Devonian  group  naturally 
resolves  itself,  overlies  the  floriferous  or  carbpnaceous  series : 
not  a  shadow  of  doubt  or  uncertainty  is  on  my*  mind  when 
I  state  it ;  the  fact  is  proved  by  every  variety  and  kind  of  re- 
cognized evidence  by  which  the  established  order  of  super- 
position of  rock  formations  has  been  determined  elsewhere; 
and  those  several  kinds  of  evidence  cannot  be  disputed  or  re- 
jected here  without  insecurity  and  peril  to  the  foundations  of 
the  geological  column,  every  stone  of  which  has  been  hewed 
and  squared  and  adjusted  by  some  wise  master  builder.  If  in 
a  perfect  faith  in,  and  uncompromising  obedience  to  those 
laws  which  alone  govern  legitimate  and  secure  induction,  I 
have  without  pretension  or  design  conveyed  embarrassment  or 
perplexity  to  the  minds  of  some,  or  unkind  or  unworthy  feel- 
ings to  the  minds  of  others,  I  am  amply  recompensed  in  the 
conscious  indifference  and  singleness  of  purpose  with  which 
I  have  read  off  the  great  truths  of  the  Creator,  and  in  a  dawn 
of  hope  that,  ere  long,  He  may  enable  me  to  sound  a  dia- 
pason note  which  may  restore  to  harmony  the  apparently  dis- 
cordant elements. 

I  have  the  honour  to  remain,  &c. 
Bleadon,  May  17,  1842.  D.  Williams. 


V.  Note  on  Fluid  Motion.  By  the  Rev.  P.  Kelland,  M.A., 
F.R.SS.  L.  $  E.,  F.C.P.S.,  %c9  ProfeSsor  of  Mathematics 
in  the  University  of  Edinburgh,  late  Fellow  and  Tutor  of 
Queen's  College,  Cambridge*. 

T^HROUGH  the  able  and.  interesting  papers  which  Prof. 

-*■       Challis   has  recently  published  in  the  Philosophical 

Magazine fj  attention  has  been  directed  to  the  circumstances 

*  Communicated  by  the  Author. 

t  S.  3,  vol.  xix.  p.  229.  vol.  xx.  p.  84,  281. 


30  Professor  Kelland's  Note  on  Fluid  Motion. 

under  which  the  equations  of  fluid  motion  can  be  solved. 
Whilst  interest  is  awakened  on  the  subject,  it  may  not  be 
deemed  utterly  unimportant  to  offer  a  few  remarks  on  the 
general  question,  especially  as  any  peculiarity  in  the  mode  of 
proceeding,  however  valueless  in  itself,  may  serve  as  a  hint 
to  guide  or  incite  others  to  the  most  important  investigations. 
The  question  before  us  appears  to  me  to  be  this — What 
new  conditions  must  we  introduce,  or  what  transformations 
must  we  effect,  in  order  that  the  four  equations  of  fluid  mo- 
tion may  be  reduced  to  four  other  equations,  each  containing 
the  differential  coefficients  of  only  one  quantity  ?  Before  this 
question  can  be  answered,  at  least  before  we  can  set  about 
introducing  any  new  conditions,  it  appears  requisite  to  an- 
swer another  question — Are  there  any  necessary  conditions  ? 
Of  course  the  answer  is  in  the  affirmative.  The  equation  of 
continuity  is  one.  But  it  is  not  the  only  one;  for  unless  the 
pressure  and  velocities  are  discontinuous  quantities,  the  equa- 
tions deduced  by  the  application  of  D'Alembert's  principle 
must  be  statical  equations,  depending  on  the  time  only  in  as 
far  as  the  velocities  depend  on  the  time.  Hence  the  relations 
which  would  exist  amongst  the  differential  coefficients  of  p, 
were  the  fluid  at  rest,  must  exist  when  it  is  in  motion ;  that  is, 

d?  p  d2p      _ 

d  x  dy  ~  dy  d  a? 

These,  then,  are  equations  of  condition ;  the  bearing  of 
which  ought  to  be  examined  previous  to  the  introduction  of 
any  new  conditions.  They  will  serve,  in  some  cases,  to  show 
what  new  hypotheses  are  admissible,  and,  in  all,  to  detect 
those  which  are  not. 

It  is  not  my  intention  to  enter  fully  into  this  subject  in  my 
present  communication.  I  shall  content  myself  with  offering 
a  few  remarks  on  the  results  of  the  mode  of  proceeding  which 
I  have  indicated,  as  applied  to  the  motion  of  incompressible 
fluids  acted  on  by  gravity  only. 

By  inclosing  within  brackets  the  complete  differentials  with 
respect  to  x,  y,  z  and  t,  we  obtain  the  following  sets  of  equa- 
tions : — 


(1.) 


ess- 

■nirdu 

My-  + 
dx 

>t  du 

dy 

p  du 
*~dz> 

es?)'- 

dx 

.fc,  dv 

dv 
r  dz> 

kit)  = 

■Kird'W 

M5S  + 

dy 

vdw 

Professor  Kelland's  Note  on  Fluid  Motion. 


31 


or 


W7/  = 


M 


du 
dy 

du 
dz 


dv       p  (Ijw 
dx  da? 


T^rdv       -ndw 


xt  dv 


dy' 

dw^ 
d~z; 


(2.) 


where 


dz 

xt       div 
dx 


dm 
d? 

du 
Tz' 

dv 


(S*.) 


p=:=  *» 

f/j/      dx' 


1.  One  way  of  satisfying  all  the  equations  is  by  supposing 
M  =  0,  N  =b,  P  =  0 ;  in  which  case  the  equations  (3.)  in- 
dicate that  udx  +  vdy  -\-  wdz  is  a  complete  differential. 

2.  Another  way  is  to  suppose  M,  N  and  P  all  absolutely 
constant;  in  which  case  the  velocities  u,  v,  w  will  be  deter- 
mined by  the  same  equation,  viz.  by  either  of  the  equations 
(1.).     Hence  it,  v,  w  all  have  the  same  form. 


Also  the  equations  (2.)  give 


M^  +  N* 

dx  dx         dx 


dv      -ndw 


0, 


&c.  &c,  orMa+  Nu+  Pwisa  quantity  whose  partial  dif- 
ferential coefficients,  with  respect  to  each  of  the  coordinates, 
is  zero.  This  quantity  is  therefore  either  zero,  or  a  function 
of  t  only. 

a.  If  it  be  zero,  udx  +  vdy  +  ivdz  is  integrable  by  a 
factor,  for  the  equation  M?i  +  N»+Pro  =  0  is  the  well- 
known  equation  of  condition  that  this  may  be  the  case. 

b.  IfMtt+Nu  +  Ptt>  —f{t),  udx  +  vdy  +  wdz  is  not 
a  complete  differential  after  being  multiplied  by  a  factor. 

The  equations  are  nevertheless  integrable  in  this  case,  and 
give  as  their  result, 

u=  F(Mz-P#,  N*-Py, /), 
t>  =  <j>(Mz  -P#,  Ns-Pj/,  t), 


*  See  ray  Memoir  on  the  Theory  of  Waves,  Trans.  Roy.  Soc.  Edin., 
vol.  xv.  p.  116. 


32  Professor  Kelland's  Note  on  Fluid  Motion. 

the  functions  being  subject  to  the  condition  MF+N4>  +  P^ 

■=/('). 

3.  If  M,  N,  P  are  explicit  functions  of  t  only,  our  equations 

(1.)  are  reduced  to 

*M      M^  +  N^  +  pi", 

at  dx  ay  a  z 

^=  M^  +  N^+P^, 
at  ax  ay  dz 


d  P      ^ifdw      ^dw  ,   „</?* 

—  =M-r-  +Nr  +  P-t"- 

dt  dx  dy  dz 


Hence 


-.  (P  u       ^.    a"* u         p   d* u     _ 
dx*       "    dxdy  dxdz" 

-_    d2  u         ^d2u       t,    d*  u 
M  -—        +  N  -j-s  +  P  t— r-  =  0, 
dxdy  dyz  dydz 

-.    d-  ti        ~~    d*  u         p d2  m  _ 
d  xdz  dydz  dx? 

from  which  equations  we  obtain,  by  eliminating  M,  N  and  P, 

rf2M  d*u  d*u  _  d*_u  /  d*u    \2  _  d*u  /   d*u  \a 
d&dfdz*       dx*\dydz)        dy*\dxdz) 

{  d*u*(  d9u\*      a    d*u      d*u      d2u    _ 

d z2  \d x dy)        "  dxdy  d xdz  dydz 

an  equation  of  precisely  the  same  form  as  that  which  occurs 
in  the  determination  of  the  principal  axes  of  a  system,  or  of 
the  diametral  lines  of  a  surface  of  the  second  order. 

Similar  equations  are  true  in  v  and  to.  We  conclude  that 
the  motion  is  such  as  to  be  symmetrical  with  respect  to  the 
coordinate  planes. 

Cor. — If  x,  y,  z  enter  in  such  a  way  into  the  expressions 

for  the  velocities  that  -=-  =  -7-,  &c,  the  equations  are  identi- 
dy      dz  ^ 

cally  true. 

4.  If  the  motion  be  confined  to  two  dimensions,  the  equa- 
tions are  reduced  to 

d  u      d  v  _ 
dx      dy         ' 

du      dv  _  p 

dy      dx  ~     ' 


Prof.  Dove's  Experiments  in  Magneto-Electricity.      33 

where  C  is  a  quantity  whose  total  differential  with  respect  to 
t  is  zero. 

a.  If  C  be  an  absolute  constant,  the  equations  for  deter- 
mining u  and  v  are 


u 


d-u     dK 
dx*  +  dy*~    ' 


+ 


=  0. 


dx*    '    dy* 
b.  If  C  be  not  an  absolute  constant,  the  equation  for  u  as- 


sumes the  following  complicated  shape : — 


ds 


ds        du 


d    dt 
dy' 

dx        dx      ds 

+ 
du                   dx 

d  J 

dy< 

dy 

ds 

d    dy 

dy'  du 

where  s 

d* u      d* u 
~  dx*       dy1' 

du  ds 
dx  dy 

du 

dy 


du 
dx' 


The  equation  for  v  is  exactly  similar  to  this. 

It  is  unnecessary  to  add  that  this  equation  is  too  complicated 
to  admit  of  integration  in  a  general  form. 

We  shall  not  prosecute  these  remarks  further ;  we  have 
offered  them  rather  for  the  purpose  of  directing  attention  to 
the  process  than  from  a  conviction  of  their  novelty  or  im- 
portance. 

VI.  Experiments  in  Magneto-Electricity,  illustrative  of  a 
Passage  in  Professor  Faraday's  Researches.  By  Professor 
Dove*. 

TJW.RADAY  says,  §  1101,  "  As  an  electric  current  acts  by 
induction  with  equal  energy  at  the  moment  of  its  com- 
mencement as  at  the  moment  of  its  cessation,  but  in  a  con- 
trary direction,  the  reference  of  the  effects  of  a  current  when 
stopped  to  an  inductive  action  would  lead  to  the  conclusion, 
that  corresponding  effects  of  an  opposite  nature  must  occur 
in  a  long  wire,  a  helix  or  electro-magnet,  every  time  that  con- 
tact is  made  with  the  electro-motor.  These  effects  will  tend 
to  establish  a  resistance  for  the  first  moment  in  the  long  con- 
ductor, producing  a  result  equivalent  to  the  reverse  of  a  shock 
or  spark.  Now  it  is  very  difficult  to  devise  means  fit  for  the 
recognition  of  .such  negative  results."     This  difficulty  may, 

*  Communicated  by  H.  Croft,  Esq.,  Teacher  of  Chemistry,  being  an  ex- 
tract from  a  letter  addressed  to  him  by  the  Author. 

Phil.  Mag.  S.  3.  Vol.  2 1 .  No.  1 35.  July  1 84-2.  D 


71 


34«       Prof.  Dove's  Experiments  in  Magneto-Electricity. 

however,  be  entirely  overcome,  so  that  perfectly  corresponding 
experiments  may  be  made  with  the  extra-current  both  at  its 
commencement  and  cessation. 

In  the  following  figure,  let  a  represent  the  rotating  anchor 
of  a  Saxton's  machine,  s  a  spiral  con- 
nected with  the  wire  of  this  anchor,  for 
the  production  of  the  extra-current,  and 
so  arranged  as  to  allow  of  iron  being 
inserted  into  it,  u  the  place  where  the 
wire  opens  by  means  of  the  spring  when 
the  anchor  is  in  a  perpendicular  posi- 
tion. I,  II,  III,  three  conductors  which 
can  be  close  by  any  body,  as  a  galvanometer,  voltameter,  &c. 
This  arrangement  allows  of  three  kinds  of  junction,  viz.  I 
and  II,  I  and  III,  II  and  III. 

If  we  call  the  primary  current  p,  and  designate  by  A 
the  reversed  extra-current  formed  at  its  commencement,  and 
by  E  the  similar  (in  direction)  extra- current  produced  at  its 
cessation,  we  find  as  follows : — As  long  as  the  wire  at  u  re- 
mains closed,  the  intensity  of  p  increases  during  the  rotation 
of  the  anchor  from  0°  to  90°,  that  is,  p  produces  the  current 
A,  and  we  obtain^?  — A.  If  we  close  I  and  III  by  means  of 
the  body  (which  extra  connexion  does  not  experience  the 
least  physiological  effects  as  long  as  u  is  closed),  it  receives 
the  shock  of  the  current  p— A,  inasmuch  as  E  cannot  be 
formed,  because  at  the  moment  u  is  opened  it  passes  out 
of  the  connexion ;  if  we  close  II  and  III  we  obtain  E ;  if  a 
straight  wire  is  substituted  for  s  there  is  no  action  :  by  closing 
I  and  II  we  get  p— A  +  E,  as  when  u  opens  the  extra-current 
is  formed  in  s.  The  presence  of  iron  in  the  spiral  s  produces 
the  following  effects : — 

I  and  III)  {p — A}.  The  shock  with  an  empty  spiral  is 
much  greater  than  when  none  is  inserted,  i.  e.  p—A  smaller 
than  p ;  when  iron  is  inserted  it  is  much  weaker,  for  A  is  in- 
creased while  p  remains  unchanged. 

II  and  III)  {E}.  The  shock  is  strengthened  by  the  inser- 
tion of  iron. 

I  and  II)  {p—  A  +  E}.  The  shock  is  much  stronger  than 
with  I  and  III,  for  p — A  +  E  is  greater  than  p— A  ;  it  remains 
almost  unchanged  when  iron  is  inserted,  because  E  increases 
almost  the  same  as  A. 

The  opening  spark  at  u  is  considerably  weaker  when  iron 
is  put  into  the  spiral,  but  recovers  its  intensity  if  II  and  III 
are  metallically  connected.  The  spark  between  II  and  III 
or  I  and  III  is  increased  in  intensity  by  the  presence  of  iron ; 


Dr.  Kane  on  the  Basic  Sulphate  of  Mercury.  SS 

the  extra-current  in  *  acts  namely  as  an  increase  of  resistance 
to  the  passage  of  the  current,  and  causes  a  greater  part  of  it 
to  flow  off  through  I  and  III  or  II  and  III.  A  voltameter 
inserted  at  u,  or  between  I  and  III  or  II  and  III,  is,  as  re- 
gards the  quantity  of  gas  obtained,  in  exact  proportion  to  the 
intensity  of  the  spark.  The  galvanometer  gives  a  similar  di- 
rection for  p,  p  —  A,  p  —  A  +  E  and  E.  All  the  results  ob- 
tained apply  as  well  for  primary  currents  whose  direction  re- 
mains the  same,  and  for  those  whose  direction  alternates. 

As  bundles  of  iron  wires,  when  electro-magnetized  by  means 
of  galvanic,  thermic,  or  frictional  electricity,  surpass  massive 
bars  of  the  same  metal  in  their  physiological  effects,  and  as 
this  phaenomenon  may  be  explained  by  electric  currents  which 
are  simultaneously  excited  in  the  iron  during  magnetization, 
it  was  interesting  to  examine  how  bundles  of  wires  would  be  in 
comparison  to  bars  when  both  were  magnetized  by  bringing 
them  in  proximity  to  a  steel  magnet.  This  can  be  effected  by 
means  of  a  Saxton's  machine  with  wooden  anchor,  in  whose  rolls 
of  wire  which  are  connected  crosswise,  a  bundle  of  iron  wires 
and  an  iron  cylinder  act  against  each  other.  The  experiment 
shows,  that  for  no  action  does  the  current  excited  by  the  bundle 
exceed  that  from  the  cylinder :  moreover,  two  similar  bundles 
of  wire,  one  of  which  was  contained  in  a  perfect,  the  other  in 
a  slit  cylinder  of  brass,  were  exactly  equal  in  all  their  effects. 

The  rotating  anchor  of  a  Saxton's  machine,  when  in  the 
dark,  and  illuminated  solely  by  the  sparks  it  produces,  appears 
to  stand  still  and  exactly  in  the  same  position,  whether  the 
anchor  be  turned  slowly  or  as  fast  as  possible.  If  there  were 
any  lapse  of  time  between  the  interruption  of  the  current  and 
the  appearance  of  the  spark,  the  anchor  would  assume  a  dif- 
ferent position,  according  to  the  rapidity  of  rotation.  As  this 
however  is  not  the  case,  it  follows  that  the  time  elapsing  be- 
tween the  interruption  of  the  current  and  the  appearance  of 
the  spark  is  not  measurable  by  this  means.      u  ^   n0vF 


VII.  Note  on  the  Composition  of  the  Basic  Sulphate  of  Mercury, 
or  Turpeth  Mineral.     By  Robert  Kane,  M.D.,  M.R.I.A. 
\  AM  induced  to  bring  forward,  in  the  present  form,  the  re- 
suits  of  some  analyses  of  the  basic  sulphate  of  mercury, 
from  the  fact  that  its  true  composition  does  not  appear  to  have 
become  generally  known  ;  the  best  authorities,  or  at  least  those 
most  in  the  hands  of  students,  giving  different  and  mostly  in- 
correct views.    Thus  both  in  Christisori's  *  Dispensatory '  and 
in  Pereira's  Materia  Medica,  this  salt  is  stated  to  have  the 

D2 


36     On  the  Composition  of  the  Basic  Sulphate  of  Mercury. 

formula  S  Oa  +  2  Hg  O,  which  in  the  former  work  is  quoted 
on  the  authority  of  Barker  and  Gerger,  neither  of  whom  was 
really  the  author  of  the  analysis,  which  is  a  very  old  one  by 
Braamcamp  and  Siquiera  Oliva,  as  Dr.  Pereira  in  his  excel- 
lent work  very  properly  states. 

Another  much  more  modern,  and  better  analysis,  by  Dr. 
Phillips*,  is  quoted  in  Turner's  Chemistry,  and  also  by  Dr. 
Christison ;  the  formula  deduced  from  it  is  3  .  S  Oa  +  8  Hg  O. 
This  analysis  is  very  nearly  correct,  yet  the  slight  error  which 
it  contains  has  the  effect  of  giving  to  the  formula  a  complexity 
which  it  does  not  properly  possess. 

In  Berzelius's  System,  and  in  Gay-Lussac's  Chimiedes  Selst 
the  formula  given  is  S  03  +  3  Hg  O.  This  I  have  found  to  be 
the  true  composition  of  the  salt,  and  it  is  adopted  by  Graham 
in  his  Elements;  yet  I  have  never  been  able  to  find  in  the 
Journals  the  analyses  on  which  it  is  founded ;  hence  I  consider 
that  the  details  of  those  by  which  I  satisfied  myself  of  its  cor- 
rectness may  have  some  interest  to  chemists. 

A.  6*503  grammes  of  perfectly  dry  and  neutral  sulphate 
of  the  red  oxide  of  mercury  were  boiled  for  a  long  time  with 
much  water,  and  the  yellow  powder  which  formed  was  col- 
lected on  a  tared  filter,  and  having  been  dried  until  it  ceased 
to  lose  weight,  was  found  to  weigh  4*623  grammes,  or  71*09 
per  cent. 

The  filtered  liquor  contained  mercury.  It  was  treated  with 
sulphuretted  hydrogen,  and  the  sulphuret  of  mercury  which 
fell  was  found,  when  perfectly  dry,  to  weigh  0*706  or  10*85  per 
cent.,  corresponding  to  10*11  of  oxide  of  mercury. 

The  excess  of  sulphuretted  hydrogen  having  been  expelled 
by  boiling,  the  sulphuric  acid  in  the  liquor  was  thrown  down 
by  nitrate  of  barytes.  The  sulphate  of  barytes  weighed  3*607 
or  55'5  per  cent.,  containing  19*08  of  sulphuric  acid.  Of  this 
3*71  had  been  united  to  10*11  of  oxide  of  mercury,  forming 
13*82  of  sulphate  of  mercury  which  had  not  been  decomposed 
by  the  water.  Hence  there  had  been  decomposed  86*18  per 
cent,  of  the  sulphate,  yielding  15*37  of  sulphuric  acid  and 
71*09  of  turpeth,  indicating  thus  a  slight  excess  of  weight, 
owing  probably  to  the  turpeth  not  having  been  rendered  ab- 
solutely dry.  Hence  100  parts  of  the  neutral  salt,  if  perfectly 
decomposed,  should  give 

17*67  of  sulphuric  acid, 
82*49  of  turpeth  mineral. 

100*16,  showing  a  slight  excess,  as  above  noticed. 
Now  as  100  of  neutral  salt  contains  73*17  of  oxide  of  mer- 
*  Phil.  Mag.  Second  Series,  vol.  x.  p.  206. 


Mr.  T.  S.  Davies  on  Pascal's  Mystic  Hexagram,       37 

cury  and  26*83  of  sulphuric  acid,  the  quantity  of  acid  left  in 
the  liquor  is  just  two-thirds  of  the  whole,  as  §'26*83  =  17*98. 
The  turpeth  contained  therefore  73*23  of  Hg  O  and  9*16  of 
S  Oa  in  the  82*49  parts,  or  in  100  parts, 

Sulphuric  acid        =  11*10~1  1on.00 
Oxide  of  mercury  =  88*90  J 
The  formula  SOs  +  3  HgO,  requires 
S63  =    40*1  =  10*91 
3  Hg  O  =  328*2  m  89*09 


368*3  100*00 
B.  4*525  grammes  of  turpeth  mineral  prepared  with  boiling 
water  were  dissolved  in  dilute  muriatic  acid,  and  the  liquor  was 
precipitated  by  sulphuretted  hydrogen.  The  sulphuret  of  mer- 
cury weighed  4*334,  being  95*76  per  cent.,  equivalent  to  89*24 
of  oxide  of  mercury.  The  liquor,  boiled  to  remove  the  excess 
of  sulphuretted  hydrogen,  gave  then  with  nitrate  of  barytes, 
1*402  of  sulphate  of  barytes,  being  30*98  percent.,  containing 
10*65  of  sulphuric  acid.  Hence  the  turpeth  mineral  con- 
sisted in  100  parts,  of 

89*24  oxide  of  mercury, 
10*65  sulphuric  acid, 
•11  loss. 
I  need  not  enumerate  more  than  these  two  results,  although 
some  others  were  obtained,  all  of  which  equally  indicated  ex- 
actly the  relation  of  S  03  +  3  Hg  O.     Of  course  it  will  be  at 
once  seen  that  I  take  for  the  equivalent  number  of  mercury 
on  the  hydrogen  scale  101*4,  and  consider  the  red  oxide  as 
containing  one  equivalent  of  each  element. 

VIII.  On  Pascal's  Mystic  Hexagram.  By  T.  S.  Davies,  Esq., 

F.R.S.,  Sj-c,  Royal  Military  Academy,  Woolwich. 
/"\NE  of  the  two  most  general  and  prolific  properties  of  the 
^-^  conic  sections  yet  known,  is  that  first  given  by  Pascal 
in  his  Essai  pour  les  Coniques,  or  rather  one  of  the  converses 
of  that  theorem,  which  we  are  told  by  Leibnitz  he  called  the 
mystic  hexagram.  It  was  made  by  him  the  foundation  of  an 
entire  system  of  conies,  of  which,  however,  all  we  know  is  the 
titles  and  general  subjects  of  the  books  into  which  it  was  di- 
vided, as  given  by  Leibnitz  in  his  letter  to  Perrier  in  ]  679. 
Mersennus  speaks  of  Pascal  having  deduced  from  it  four  hun- 
dred corollaries ;  and  Desargues  (who  says  that  in  his  time, 
1642,  it  was  called  "the  Pascal")  tells  us  that  it  contains,  either 
as  cases  or  immediate  consequences,  the  whole  of  the  propo- 
sitions in  the  first  four  books  of  Apollonius.  The  well-known 
properties  of  the  quadrilateral  inscribed  and  circumscribed 
to  the  conic  section,  known  by  modern  geometers  as  "the 


38       Mr.  T.  S.  Davies  on  Pascal's  Mystic  Hexagram. 

theory  of  the  pole  and  polar ;"  the  description  of  the  conic 
sections  by  revolving  line9  or  the  sides  of  revolving  angles, 
first  suggested  by  Newton,  and  followed  out  in  detail  by  Mac- 
laurin  and  Braikenridge,  also  flow  at  once  from  this  theorem. 
In  short,  for  generality  and  facility  of  employment  there  is 
only  one  other  principle  that  can  compete  with  it;  which  is 
that  of  the  anharmonic  ratio  of  M.  Chasles,  as  developed  in 
the  notes  to  his  Apercu  Historique  des  Methodes  en  Geometric. 

The  demonstration  of  this  theorem  was  not,  however,  pub- 
lished by  Pascal;  nor,  I  think,  has  there  ever  been  given 
a  strictly  geometrical  demonstration  in  the  manner  of  the  an- 
cients. For  the  circle  the  demonstration  is  very  simple  and 
elegant;  of  which  four  specimens  may  be  seen  in  the  Mathe- 
matical Repository,  vol.  iv.  New  Series,  one  of  which  by  Mr. 
Ivory  is  inserted  by  Dr.  Bland  in  his  Geometrical  Problems. 
The  method  of  projection  is  employed  to  extend  it  to  the  other 
conic  sections :  but  admitting  the  theory  of  transversals,  the 
property  admits  of  a  very  short  and  direct  demonstration  for 
the  conic  sections  generally.  The  proposition  itself  in  the 
general  form  was  proposed  in  the  Ladies'  Diary  for  the  present 
year,  to  be  established  without  any  direct  or  implied  use  of  the 
circle ;  and  in  reply  to  that,  the  demonstration  above  alluded 
to  has  been  given,  and  will  appear  in  the  next  year's  Diary. 

Many  attempts,  with  different  degrees  of  success  and  ele- 
gance, have  been  made  by  the  continental  geometers  to  solve 
this  by  the  method  of  coordinates.  I  believe,  however,  that 
except  by  Sir  John  Lubbock*  and  an  imperfect  sketch  of  my 
ownf  (which  is  here  followed  out  and  completed),  no  one  of 
our  countrymen  has  looked  at  the  subject  in  this  light.  I  am 
led,  therefore,  to  think  that  the  following  investigation  will 
be  interesting  to  geometers ;  it  being,  I  believe,  very  different 
from  any  process  published  by  other  writers. 

The  o  rem.  If  the  three  pa  irs  of  opposite  sides  of  a  hexagon 
inscribed  in  a  conic  section  be  produced  to  meeU  the  three  'points 
of  concourse  will  be  in  one  straight  line. 

Take  the  opposite  sides 
A  D,  B  C,  uniting  in  O, 
as  axes  of  coordinates ;  and 
denote  the  distances  O  A, 
O  B,  O  C,  O  D  by  «,  ft 
y,  8,  and  the  two  remain- 
ing angular  points  F  and 
E  of  the  hexagon  by  (xx  y^) 
and  (a?8  ya). 


*  Phil.  Mag.  Third  Series,  vol.  xiii.  p.  83. 
t  Solutions  to  Hutton's  Questions,  p.  505. 


Mr.  T.  S.  Davies  on  Pascal's  Mystic  Hexagram.       39 

The  general  form  of  the  equation  of  the  conic  section  re- 
ferred to  the  axes  O  B,  O  D  is 

ay*  +  bxy  +  cx*  —  dy  —  ex  +/  =  0 (1.) 

The  equations  of  the  other  four  sides  of  the  hexagon  will  be 

(A  F) xx  (y  -  a)  =  x{yx-a) (2.) 

(BE) y(*2-/3)  =  y2(*-/3) (3.) 

(CF) y(xl-y)=yl(x-y) (4.) 

(DE) *9(y-*)  =  *(y8-*) (5.) 

Let  (Xj  Yx)  be  the  intersection  G  of  the  lines  A  F,  B  E  de- 
noted by  equations  (2.)  and  (3.) ;  and  (X2  Y2)  be  that  H  of 
C  F,  D  E  denoted  by  (4.)  and  (5.) :  then  we  readily  find 

1    *!&  -  (*2  -  0)  55  - «) 

2    a£JI  -  K  -  y)  (y«  - 8) 

(a  *,  +  /3j/x  -«/3)  ?/2 


Yx  = 


Y2  = 


*\V%  -  (*i  -  Z3)  (3/1  -  «J 

(&^2  +  7.y2-7g).yi 
•*'2yi  -  (*i  -  7)  (y2  -  8). 


(6.) 


Write  Dt  and  D2  for  the  denominators  of  X15  Yj  and  X2,  Y2; 
and  find  the  values  of  X2  Yj  and  Xll  Y2,  disregarding  for  the 
present  the  common  denominator  Dx  D2.  To  effect  this,  ac- 
tually multiply  the  values  of  X2  Yx  in  (6.),  and  likewise  those 
of  Xt  Y2 :  then  these  two  expressions  are  respectively, 


{byy*? + (*s+ &y)xzy*+ a^x22 


DiD2 

■  fiy(a  +  'S)y2-a'S((Z  +  y)x2  +  u[Zytyx1yl 


D,D, 


=  X,Y, 


XXY3 


Now  since  A,  B,  C,  D  are  the  points  of  intersection  of  the 
curve  denoted  by  (1.)  with  the  axes  of  coordinates,  we  get  by 
putting  x  and  y  successively  equal  to  zero,  the  values  of  a,  /3, 
7,  8  in  terms  of  the  coefficients  of  (J.),  as  follows: — 

_  d  +   Vd?-baf_  &  _ 


2a 


8  = 


d-  VcP-baf 


2« 


y  = 


e 

— 

Ve>- 

-4  c/ 

+ 

2c 

e 

Ve*- 

-4  c/ 

2c 


Insert  these  values  in  the  former  of  the  equations  marked  (7.): 
then  there  results  as  the  value  of  X2  Yx .  T)x  D2, 

ed-  Vtf*-*qf)(e*^icf) 


(7.) 


Wi2- 


2/ 


X\V\  +  cx^—dy  —exx  +/}*2y2. 


40       Mr.  T.  S.  Davies  on  Pascal's  Mystic  Hexagram. 

But  as  xx  yx  is  a  point  in  the  conic  section  denoted  by  (1.),  we 
have 

ay?  +  ex?  —  dyx  —  e  xx  +/=  —  bxxyx, 
which  substituted  in  the  preceding  expression  gives  us 

Again,  since  Xj  Y2  is  the  same  function  of  <r2  y%  tnat  X2  Yj 
is  of  xx  yXi  we  shall  in  the  same  way  obtain 

*i*tr  2/D^  *•!(*•?»*  «\W 

It  follows  from  (8.)  and  (9.)  that  we  have  the  equation 

X2  Yj  —  Xj  Y2  =  0 

in  virtue  of  the  identity  of  the  terms  which  compose  them  : 
and  this  is  the  familiar  test  of  the  line  G  H  passing  through  O 
the  origin  of  coordinates,  and  furnishing,  therefore,  a  complete 
proof  of  the  "  Pascal." 

Scholium  1.  — When  the  equation  is  of  the  above  form  (1.) 
with  the  exception  of  the  last  term  negative, 

ay2  +  b  xy  +  ex*  —  dy  —  ex  —f  =  0, 

the  origin  O  will  be  within  the  curve ;  and  the  Pascal  will  then 
become  an  extension  of  a  theorem  of  Pappus  (prop.  139, 
book  vii.)  respecting  a  quadrilateral  figure,  to  the  conic  sec- 
tions generally. 

The  proposition  in  reference  to  this  case  may  be  stated  as 
follows: — 

F 

Let  A  Z),  B  C  be  the  diagonals  of 
a  quadrilateral  inscribed  in  a  conic  sec- 
tion :  from  A  C  draw  lines  A  F,  C  Fto 
any  point  F  in  the  arc  B  D,  and  from 
B  D  to  any  point  E  in  the  arc  A  C, 
meeting  the  former  in  G  H;  then  the 
line  G  H  will  pass  through  O  the  inter- 
section of  A  Z),  B  C. 

Scholium  2. — The  theorem  of  Pappus,  above  referred  to, 
applies  to  the  case  where  the  conic  section,  as  the  locus  of  E 
and  F,  is  replaced  by  the  straight  lines  A  C,  B  D.  To  deduce 
this  from  the  preceding  investigation,  it  is  only  necessary  to 
multiply  together  the  two  equations  of  the  lines  A  C,  B  D, 
which  gives  an  equation  of  the  general  form  (I.),  and  to  which 
the  same  process  may  be  applied  as  that  already  employed : 
for  the  conclusion  is  deduced  from  (1.)  being  the  equation  of 


Mr.  T.  S.  Davies  on  Pascal's  Mystic  Hexagram.       41 

the  locus  (or  loci)  of  E  and  F.  A  more  independent  and  per- 
haps more  elegant  process,  would  be  the  following ;  the  ge- 
neral principle,  however,  being  the  same  as  that  before  em- 
ployed. 

Let  the  absolute  lengths 
of  the  lines  O  A,  O  B,  O  C, 
O  D  be  a,  /3,  y,  8;  then  the 
several  points  concerned  will 
be  denoted  as  under. 


(A)....(0,-«) 
(B)....(-/3,0) 
(C)....(y,0) 


(D)....  (0,3) 

(F)....(^) 
(E)  ,...(a?3y2) 


and  the  several  lines  concerned  will  be  expressed  in  the  usual 
manner,  thus : — 

(BD)....  -/3y  +  8*=-/38 (1.) 

(AC)  ....       yy  —  *%=  —  ay (2.) 

(AF)  ....    *!(y+«)=*(y,  +  «) (3.) 

(BE)  ....     y(ar9  +  |3)=ya(*  +  jB).  .  . (4.) 

(CF)  ....     t,(xl-y)  =  y1(x-y) (5.) 

(DE)  ....     *9(y-8)  =  *(y8-8) (6.) 

Denoting  as  before  G  and  H  by  (Xj  Ya)  and  (X2  Y2),  we  get 

(«ga  +  /3y2  +  «£)*! 

*i  #2  -  (*«  +  0)  (yi  +  a) 

(8  xx  +  y  y,  -  y  8)  #a 


X1=- 

x2=  + 

Y,=  - 


Y,=  + 


#a  2/1  -  to  -  y)  (y«  - 8) 

(q^t  +  $yx  +  «/3)y2 

*i  2/2  -  (*«  +  Z3)  (yi  +  «) 

(Sjt2  +  7^2-78)y2 


> 


(70 


*2yi-  (*i  -7)  (y2-8). 

Also,  since  (^j  yx)  is  in  (1.),  and  (ar8  y^  in  (2.),  we  have  the 
equations, 

/3yi  =  ^x  +  /38 (8.) 

yy2  =  «.r2-ay (9.) 

In' the  values  of  X15  X2  substitute  the  values  ofyx,  y2  from 
(8.)  and  (9.),  and  in  those  of  Yx,  Y2  those  of  xv  x^  from  the 


42     Mr.  Balmain's  New  Process  for  preparing  Oxygen, 

same  equations ;  and  denote,  as  before,  the  denominators  by 
Dj  and  D2  respectively :  then 

v  _  *  (ft  +  7)  *i  **        v  _/3(*  +  g)ytyn 

>  . .    (10.) 

Substitute  these  in  the  expression  X2  Yl  —  Xj  Y2,  and 
we  have  X^-X^ 

_  («  +  8)Q3  +  y)jfly1.jr8ya  _  Q8  +  y)  («  +  8)  g8y8.gi.y» 
DiD2  D.D, 

=  0, 
which  is  again  the  ordinary  criterion  of  G  H  passing  through 
the  origin,  O. 

Royal  Military  Academy, 
May  Uh,  1842. 

IX.  New  Process  for  Preparing  Oxygen  By  W.  H.  Balmain, 

Esq. 

To  the  Editors  of  the  Philosophical  Magazine  and  Journal. 
Gentlemen, 

/"^XYGEN  being  much  in  request  for  the  oxyhydrogen 
^•f  blow-pipe,  and  indeed  for  purposes  of  illumination,  it 
is  important  to  have  an  expeditious  and  cheap  process  for 
preparing  it.  Moreover,  in  the  present  day,  when  practical 
chemistry  is  becoming  so  popular,  it  will,  independently  of 
all  matter  of  expense,  be  no  insignificant  acquisition  to  the 
lecturer  and  juvenile  experimentalist  to  have  a  ready  method 
of  preparing  the  principal  supporter  of  combustion.  It  has 
occurred  to  me  that  it  may  be  prepared  from  bichromate  of 
potash  by  the  action  of  sulphuric  acid;  and  as  the  process  has 
upon  trial  proved  successful,  I  beg  leave  to  suggest  it  to  those 
whom  it  may  concern  through  the  medium  of  your  Journal. 

A  mixture  of  three  parts  of  bichromate  of  potash  and  four 
parts  of  common  sulphuric  acid  contained  in  a  capacious  re- 
tort, will,  on  the  application  of  a  moderate  heat,  yield  pure 
oxygen  with  a  rapidity  entirely  at  the  command  of  the  ope- 
rator. 

K      Chr2  .  S4     H4  nrnAl„a    K      SandChr,  03+  S, 

47-5+104=  151-5  ana  160+36=196  Proauce  47'5+40+  56  +24+120 

=  287'5and36and24' 


Mr.  Drach  on  the  Hourly  Observations  at  Leith  in  1824-25.  43 

This  process  is  cheaper  than  that  of  heating  chlorate  of 
potash  ;  for  two  parts  of  bichromate  of  potash  will  produce  as 
much  oxygen  as  one  of  chlorate  of  potash,  while  the  latter  is 
nearly  three  times  the  price  of  the  former;  and  besides  this, 
the  residue  of  the  first  is  valuable,  and  may  be  reconverted 
into  bichromate  of  potash.  It  is  likewise  a  more  convenient 
process  than  any  at  present  known,  since  it  may  be  conducted 
at  so  low  a  temperature  that  an  ordinary  retort  and  lamp  may 
be  used  for  the  production  of  a  considerable  quantity  of  oxygen. 
Mechanics'  Institution,  W.  H.  BALMAIN. 

Liverpool,  May  10,  1842. 

[Note. — I  have  tried  this  process  and  find  that  it  answers 
very  well,  the  gas  being  given  off,  I  think,  with  greater  readi- 
ness than  when  sulphuric  acid  and  binoxide  of  manganese  are 
employed.  Occasions  I  have  no  doubt  will  occur  in  which 
this  method  may  be  advantageously  substituted  for  others. — 
R.  P.] 

X.  On  Sir  D.  Brewster's  Deductions  from  the  Hourly  Ob- 
servations at  Leith  in  1824-25.  By  S.  M.  Drach,  Esq., 
F.R.A.S. 

To  the  Editors  of  the  Philosophical  Magazine  and  Journal. 
Gentlemen, 
HPHE  deductions  alluded  to  in  the  title  of  this  article,  as 
-■-  detailed  in  the  Edinburgh  Philosophical  Transactions, 
vol.  x.,  flow  from  any  expression  of  the  temperature  in  func- 
tions of  the  time.  Let  v  =  the  temperature,  /  =  the  time ; 
—  T  =  a  fixed  instant ;  then  to  be  real  v  =  function  of 

J.f+T\\    ('  +  T)\  log  (t  +  T),  *™ i (t  +  T),  constant  \, 

which  is  developable  into  the  series 

r;  =  A+B(*  +  T)  +  C  (t  +  T)2  +  D(*  +  T)3  +  &c. 

A,  B,  C,  &c.  are  functions  independent  of  the  time,  and  com- 
prehending the  latitude,  declination,  radiation,  &c. 

When  t  =  -  T,  v  =  A. 

First.  If  A  =  the  daily  mean  temperature,  t  =  —  T  =  time 
of  morning  mean,  and  0  =  B  +  C  {t  +  T)  +  D  (t  +  T)2,  +  &c. 
gives  the  other  times  of  mean  daily  temperature. 

There  being  only  one  (evening)  mean,  this  series  must  be 
very  convergent,  and 

B  B 

t  —  —  T  —  j^t  or  more  correctly,  t  =  —  T ~ ; 


thus  B  D  is  very  much  less  than  C2. 


c-c-D 


44  Mr.  Drach  on  Sir  D.  Brewster's  Deductions 

Secondly.     For  the  maximum  and  minimum  times : 

^  =  0=B  +  2C(*+T)+3D(*  +  T)2, 


,_        t       C     .       /C2-3BD. 
*  l~~  L  ~3D+V WW~~  ' 

the  first  corresponds  to  a  minimum,  the  second  to  a  maximum  ; 
the  former  being  nearer  than  the  latter  to  the  morning  mean. 
Thirdly.     If  A,  T  be  the  temperature  and  epoch,  and  t 
not  great, 

»  =  (A  +  ^^T2)  +  (B++32DCTf)^(^  +  3DT)^  +  D.^ 

is  the  equation  for  some  time  on  each  side  of  T ;  neglecting 
the  small  quantity  D  t3,  it  is  that  of  a  parabola,  having  v  for 
an  absciss  and  t  for  an  ordinate. 

Fourthly.  Beginning  at  noon,  T  =  0,  tt=A  +  Btf+C*2 
+  D  tf3  +  &c.  Taking  the  mean  of  homonymous  hours  (the 
unit  of  t  being  one  day),  that  is,  taking  the  mean  of  t  +  £  and 
t  —  i»  we  obtain 

„,+#  =  A  +  B(<  +  i)  +  c(^  +  i-  +  l)  +  &c. 
=  A  +  T  +  Te  +  (B  +  t)  '  +  C'2  +  &c- 

rj 

Whereof  the  mean  =  A  +  —  +  B  t  +  C  t*  &c.      For  the 

16 

mean  of  the  twenty-four  hours,  we  add  —  t  and  +  t,  there- 
fore 

24A      2C      12*  f8        2E      12<    f* 
General  mean  =  _  +  _  2^  _2  +  — .  2^  .  ^ 

650  C  60810  E        A    ,    C     |    Q 

=  A  +  12^576  +  18757?  =  A  +  H  +  &C* 
Now  C,  D,  &c.  being  small,  it  is  evident  this  nearly  agrees  with 
the  homonymous  mean,  the  chief  error  B*+  C(  — — TT  =  p^  ) 

indicating  very  nearly  a  progressively  uniform  error,  so  that 

5  1 

by  combining  t  and  —  t  this  error  =  — —  C  =  —  C  must  very 

nearly  vanish. 


from  the  Hourly  Observations  at  Leith  in  1824-25.      45 

These  extremely  general  theoretical  results  are  amply  con- 
firmed by  the  above-mentioned  observations. 

London,  December  8,  1841.  S.  M.  D. 


APPENDIX. 


These  Leith  observations  give  the  temperature  at 


P.M. 

lhr  =  51-149 
51-470 
51-532 
51-239 
50-872 
50-294 


P.M. 

7hr 

8 

9 
10 
11 
12 


49-544 
48*624 
47-829 
47*276 
46-803 
46-398 


A.M. 

lhr  =  46-134 


45-933 
45-689 
45-449 
45-394 
45-653 


A.M. 

7hr 

8 

9 
10 
11 
12 


The  sums  of  the  homonymous  hours  are — 


p.m.  and  a.m. 
1  hr  =  97-283 


97*403 
97-221 
96-688 
96-266 
95-947 


p.m.  and  a.m. 
7  hr  =  95-827 


8 

9 

10 

11 

12 


95-653 
95-888 
96-288 
96-753 
97-175 


Sums. 
193-110 
193-056 
193-109 
192-976 
193-019 
193-122 


46-283 
47*029 
48-055 
49-012 
49-950 
50-777 

Diff. 
+  1-456 
+  1-750 
+  1-333 
+  0-400 

—  0-487 

—  1-228 


The  near  agreement  in  the  third  column  shows  the  series 

'expressing  the  daily  temperature  to  be  very  nearly  a  periodic 

one,  and  of  the  form  A=H  +  Asin*+#  cos  t  +  B  sin  2  t 

+  b cos  2  t  +  C  sin  3  *  +  c cos  3  /  +  E  sin  4  t  +  e cos 4  t ;  h, 

H,  &c.  being  thermometric  degrees,  and  t  the  time. 

Hence,  as  in  my  paper  on  the  Plymouth  barometric  oscil- 
lations*, we  can  deduce  the  rule,  that  if  the  thermometer  be 
observed  only  four  times  a  day,  at  intervals  of  six  hours,  com- 
mencing at  any  time,  the  resulting  average  is  all  but  equal  to 
that  deducible  from  twenty-four  hourly  observations.  The 
greatest  difference  is  here  48°-266  (mean)  —  I  (l92°-976) 
=  0°*022  =  one  forty -Jifth  of  a  degree  of  Fahrenheit. 

The  differences  of  the  homonymous  hours  (p.m.  — a.m.)  are 

lhr= +5-015  4  hr  =+ 5*795  |7hr=+ 3-161   10hr=  — 1-736 

2  +5-537  5  +5-478  8  +1*595  11  —3*147 

3  +5-843  6  +4-641 1 9  — 0'226  12         —4-379 

Whence  by  a  process  exactly  similar  to  the  one  in  the  paper 
above  alluded  to,  there  results 

temp,  from  noon  =A  =  48°-266 +  2°*1437  sin*  +  2°- 1354  cos* 

+  0-295  sin  2  t  +  0-308  cos  2  t  —  0*1302 


*  Phil.  Mag.,  June  1842  (Third  Series,  vol.  xx.  p.  477). 


46       Mr.  Earnshaw  on  the  Motion  of  Luminous  Waves.  i 

sin  3^+  0'00115cos3£— 0'00715sin4£ 

+  0-00686  cos  4£, 
temp,  froml    =  48o.266  +  3o.0257sin^  +  44o53f)  +  0o.4265 
noon  =  h  J  v  ' 

sin  (2  *  +  46°  14')  +  0°  '1302  sin  (3  t 

+  1 79°  30')  +  0*0099  sin  (4  t  + 1 36°  50'). 

The  quantities  c,  E,  and  e  are  the  only  ones  wherein  the 
separate  values  in  each  combination  disagree,  but  this  is  not 
very  material,  owing  to  the  smallness  of  these  quantities. 

London,  April  29,  1842.  S.  M.  D. 

XL  On  the  Motion  of  Luminous  Waves  in  an  Elastic  Me- 
dium, consisting  of  a  system  of  detached  particles,  separated 
by  finite  intervals.  By  S.  Earnshaw,  M.A.  of  St.  John's 
College,  Cambridge. 

THE  equations  obtained  at  the  close  of  my  last  communi- 
cation on  this  subject  (vol.  xx.  p.  373)  involve  six  co- 
efficients, A,  B,  C,  D,  E,  F.  From  the  peculiar  manner  in 
which  they  enter  those  equations  it  is  known,  that  if  the  co- 
ordinate axes  be  turned  through  proper  angles,  their  directions 
still  remaining  rectangular,  the  equations  will  assume  the 
forms 

d?z=-k*Sj,    4Sm~'&:»    d^^-lcit 

These  show  that  vibrations  of  m  parallel  to  any  one  of  the 
axes  of  dynamical  symmetry  cannot  be  affected  by  vibrations 
which  are  parallel  to  the  other  axes.  Simple  as  these  equa- 
tions are,  they  have  precisely  the  same  degree  of  generality  as 
the  original  ones,  for  the  motion  of  the  particle  m.  It  might 
not  happen  that  the  axes  of  dynamical  symmetry  for  every 
particle  would  be  parallel  to  those  for  m,  and  that  the  same 
position  of  the  coordinate  axes  would  reduce  the  equations  of 
motion  for  the  other  particles  of  the  medium  to  the  same  form, 
and  cause  them  to  have  the  same  coefficients  as  for  m.  A 
condition  equivalent  to  mechanical  homogeneity  of  the  me- 
dium must  be  fulfilled  that  this  may  be  the  case.  It  is  neces- 
sary therefore  to  appeal  to  experiment  for  license  in  this 
matter.  By  experimental  means  we  learn  that  the  positions 
of  the  axes  of  elasticity  for  waves  of  a  given  length  are  fixed, 
and  that  the  velocity  of  transmission  of  such  waves  is  uniform, 
and  that  both  these  properties  are  independent  of  the  thick- 
ness of  the  medium  :  hence  we  may  assume  that  fcl  £2  k3  have 
constant  values  through  the  whole  interior  of  a  medium,  and 
that  the  equations  in  the  simple  forms  above  given  are  appli- 
licable  to,  and  fully  represent  all  the  properties  of,  the  trans- 


Mr.  Earnshaw  on  the  Motion  of  Luminous  Waves.      47 

mission  of  waves  of  light  through  a  luminiferous  medium.  It 
is  necessary  also  to  observe  that  the  quantities  kx  &2  k3  are  all 
possible,  and  finite ;  for  were  one  of  them  otherwise,  vibra- 
tions parallel  to  the  corresponding  axis  of  symmetry  could  in 
no  case  be  transmitted  ;  but  as  no  media  having  this  property 
have  been  yet  found,  we  are  permitted  to  assume  that  the  law 
of  molecular  force  and  the  mode  of  arrangement  of  the  parti- 
cles are  such  as  to  make  kx  &2  k3  possible  in  all  cases.  We 
are  now  at  liberty,  without  affecting  the  generality  of  our  in- 
vestigations, to  suppose  that  the  axes  of  symmetry  were  the 
coordinate  axes  employed  in  my  former  paper ;  in  which  case 
D  =  E  ==•  F  m  0,  and  the  equations  of  motion  are 

^=-2S(Arsin^).£, 
^=-2£(Brsin^).,,, 

^r=-2s(Crsin^^).?; 

wherefore  if  w  t/  o"  be  the  velocities  of  transmission  of  vibra- 
tions which  are  parallel  to  the  axes  of  symmetry,  and  if  A  be 
the  length  of  the  wave,  then 


«"(t)'-*(B^). 

«-e)'-*(*"2)- 


The  right-hand  members  of  these  equations  involve  A  im- 
plicitly} in  a  manner  which  depends  upon  the  arrangement  of 
the  molecules  of  the  aether  and  the  law  of  molecular  force ; 
and  thus  a  relation  is  established  between  the  length  of  a  wave 
and  the  velocity  of  its  transmission ;  but  unhappily  the  ex- 
pressions are  of  such  a  nature  as  to  imply  that  there  is  di- 
spersion in  vacuo.  The  case  therefore  stands  thus :  dispersion 
in  a  refracting  medium  cannot  be  accounted  for  on  the  finite-in- 
terval theory  unless  there  be  also  dispersion  in  vacuo.  Now 
as  there  is  no  dispersion  in  vacuo,  I  infer  generally,  that  the 
finite-interval  theory  cannot  account  for  dispersion. 

Again,  by  referring  to  my  former  communication,  it  will 
be  seen  that  the  equations  of  motion  do  not  depend  upon 
the  position  of  the  front  of  the  waves  traversing  the  me- 


48       Mr.  Earnshaw  on  the  Motion  of  Luminous  Waves. 

dium  *.  They  show  that  a  particle  may  vibrate  in  any  di- 
rection, and  that  the  vibrations  have  no  necessary  reference 
to  the  direction  of  transmission.  And  it  is  to  be  kept  in 
mind  that  we  have  found  our  equations  without  the  aid  of 
any  hypothesis  respecting  arrangement ;  and  therefore  it 
is  impossible  by  means  of  arrangement  to  affect  our  results. 
And,  again,  we  have  assumed  no  particular  law  as  the  law 
of  molecular  action.  I  have  elsewhere  shown  that  there 
are  laws  under  which  the  motion  of  the  aethereal  particles 
would  not  be  a  vibratory  but  a  translatory  motion :  we  have 
rejected  these  laws  in  assuming  that  k1  h2  k3  are  all  possi- 
ble :  but  of  all  the  laws  which  would  give  vibratory  motions 
and  satisfy  the  known  conditions  of  transmission  we  have  re- 
jected none :  all  possible  cases  are  therefore  included  in  our 
results.  I  consider  it  therefore  as  proved  incontestably,  that 
according  to  the  finite-interval  theory  there  can  be  no  con- 
nexion between  the  directions  of  the  vibrations  and  the  law  of 
molecular  force.  Hence,  then,  the  transversality  of  vibrations 
never  can  be  established  on  that  theory,  and  is  therefore  op- 
posed to  it.  Perhaps  it  is  proper  to  remark  here,  that  I  have 
not  taken  account  of  the  direct  action  of  matter  upon  the  aether; 
but  as  my  results  are  independent  of  arrangement,  it  is  ob- 
vious that  the  indirect  effect  of  matter  is  included  in  them. 
Consequently  the  indirect  effect  of  matter  never  can  assist  us 
in  accounting  either  for  the  transversality  of  vibrations  or  for 
dispersion.  If,  therefore,  these  facts  are  to  be  accounted  for, 
we  must  look  to  the  direct  action  of  matter  on  the  aether. 

These  are  some  of  the  results  which  I  proposed  to  lay  before 
your  readers  in  commencing  these  papers.  They  clear  away 
a  great  deal  of  mist  from  the  finite-interval  theory,  and  point 
out  the  only  direction  in  which  we  can  look  for  success.  Mr. 
O'Brien  has  proceeded  in  that  direction,  and  has  announced 
that  in  that  quarter  "  the  hypothesis  of  finite  intervals  cannot 
be  correct ;"  if  he  succeed  in  establishing  that  position,  and  I 
doubt  not  he  will,  the  finite-interval  theory  may  be  laid  aside, 
and  mathematicians  will  then  be  at  liberty  to  pursue  a  more 
promising  hypothesis.  In  the  first  of  my  papers  I  gave  my 
reasons  for  thinking  that  those  persons  have  fallen  into  error 
who  suppose  that  the  theory  in  question  has  accounted  for 

*  For  &i  k'2  £3  are  absolutely  constant  for  a  given  value  of  *  ;  and  by 
transposing  the  coordinate  axes  back  again  from  the  axes  of  dynamical 
symmetry  to  their  original  positions,  we  shall  of  course  obtain  the  equa- 
tions exhibited  in  that  communication  :  and  by  the  nature  of  this  process, 
the  constants  (i.  e.  A,  B,  C,  D,  E,  F)  will  involve  only  kx  £2  ks  and  the  an- 
gles of  transposition :  they  are  therefore  independent  of  the  position  of 
the  waves'  front. 


Mr.  Earnshaw  on  the  Motion  of  Luminous  Waves.      49 

the  experimental  dispersion  of  light.  The  only  reference  to 
that  communication  which  I  have  yet  seen,  is  in  the  postscript 
of  Professor  Kelland's  letter  in  your  Journal  of  the  present 
month,  where,  after  admitting  that  all  the  values  of  q  given  in 
his  memoir  on  Dispersion  are  erroneous,  the  Professo  states 
that  the  error  is  of  no  importance,  seeing  that  the  fo  nulse 
are  of  necessity  capable  of  fulfilling  the  conditions  requinted.of 
them.  This  must  be  admitted,  I  think,  to  be  ratfcer  an  un- 
usual mode  of  disposing  of  a  matter  of  such  importance  as  the 
numerical  verification  of  his  theory.  Am  1  to  understand 
him  to  say,  that  his  formulae  are  of  necessity  capable  of  pro- 
ducing correct  results  even  if  the  data  employed  be  erroneous? 
May  I  not  then  ask,  what  is  the  nature  of  the  connexion  of 
these  formulae  with  theory  ?  and  in  what  degree  is  his  theory 
supported  and  strengthened  by  coincidences  obtained  from  such 
formulae  ?  I  take  it  for  granted  that  the  results  were  consi- 
dered as  strengthening  the  theory  in  some  way,  else  why 
have  they  been  published  both  in  Professor  Kelland's  me- 
moir and  in  other  places  in  connexion  with  theory  ?  Now  I 
showed,  and  Professor  Kelland  has  now  allowed,  that  funda- 
mental errors  were  made  in  the  application  of  the  data ;  and 
the  results  thus  obtained  were  announced  as  proofs  of  the 
soundness  of  the  theory.  I  wish  to  ask,  then,  how  the  results 
could  have  any  power  at  all  in  confirming  the  theory,  if  the 
formulae  were  of  necessity  capable  of  producing  correct  results 
from  correct  or  incorrect  data  indifferently  ? 

I  am  aware  that  the  position  which  I  have  taken  in  the 
present  paper  touching  the  transversality  of  vibrations  is  al- 
ready by  anticipation  controverted  in  Professor  Kelland's 
letter  to  Mr.  O'Brien  (p.  377),  where  we  read,  that  "if  the 
law  "  of  molecular  force  "  be  that  of  the  inverse  square  of  the 

distance the  vibrations  are  transversal  only."     I  regret 

that  the  necessity  of  defending  my  own  investigations  from 
implied  error  prevents  me  from  letting  this  statement  pass 
without  comment.  I  have  turned  to  the  part  of  the  memoir 
to  which  the  Professor  has  directed  attention,  and  shall  here 
state  in  as  few  words  as  possible  the  objections  which  seem  to 
me  to  lie  against  the  conclusion  there  come  to ;  merely  pre- 
mising, that  if  I  have  misunderstood  the  nature  of  the  reason- 
ing, 1  am  open  to  correction.     My  objections  are 

1st.  I  find  it  stated  that  "v  and  o"  are  possible  and  equal, 
but  o'  impossible  and  of  a  different  magnitude ;"  and  thence 
it  is  inferred  that  "  attractive  forces  give  rise  to  transversal 
vibrations  only."  Now  it  appears  to  me  that,  admitting  the 
former  part  of  this  to  be  true,  there  is  some  error  in  the  in- 
ference.    For  since  y  v'  v"  are  the  velocities  of  the  wave,  and 

Phil.  Mag.  S.  3.  Vol.  21.  No.  135.  July  1842.         E 


50  Royal  Society. 

not  of  the  particles,  the  inference  should  have  been,  that  there 
is  one  direction  in  which  waves  cannot  he  transmitted ;  or,  in 
other  words,  that  the  (Ether  is  opake  in  one  direction. 

2nd.  But  I  am  unable  to  discover  on  what  ground  it  is 
stated  that  v'  is  impossible.  I  see  no  reason  why  we  may  not 
say  with  equal  truth  that  u'  is  possible,  and  v  and  v"  impossi- 
ble; in  which  case  ihe  inference  is,  that  the  (Ether  is  trans- 
parent in  one  direction  only. 

3rd.  After  all,  it  appears  to  me  that  the  implied  impossi- 
bility of  some  one  (or  two,  as  the  case  may  be)  of  the  quantities 
u  u'  v"  has  reference  to  a  fact  distinct  from  either  of  these  in- 
ferences, viz.  the  instability  of  the  medium  when  the  forces  vary 
according  to  the  Newtonian  law.  If  u'  be  impossible,  as  is 
asserted  in  the  memoir  referred  to,  it  shows  that  the  sines  and 
cosines  of  all  angles  in  which  v'  occurs  ought  to  have  been 
written  in  the  form  of  exponentials,  and  that  some  equation 
has  been  integrated  by  sines  or  cosines  which  ought  to  have 
been  integrated  by  exponentials.  Hence  it  follows  that  a 
vibrating  motion  of  the  particles  is  impossible,  and  that  the 
particles  of  the  whole  medium  are  in  a  state  of  either  neuter 
equilibrium,  or  unstable.  In  either  case  it  is  unfit  for  the 
transmission  of  light,  and  results  derived  from  it  are,  if  at  all, 
only  accidentally  applicable  to  the  phsenomena  of  nature. 

Cambridge,  May  3,  1842. 


XII.    Proceedings  of  Learned  Societies. 

ROYAL  SOCIETY. 

[Continued  from  vol.  xx.  p.  512.] 

March  17,  r|^HE  reading  of  a  paper,  entitled  "  Contributions  to 

1842.  ■*■  the  Chemical  History  of  the  Compounds  of  Palla- 
dium and  Platinum,"  by  Robert  Kane,  M.D.,  M.R.I.A.,  communi- 
cated by  Francis  Baily,  Esq.,  V.P.R.S.,  was  resumed  and  concluded. 

The  author  states  it  to  be  his  object,  in  this  and  in  some  subse- 
quent papers,  to  examine  specially  the  composition  and  properties 
of  the  compounds  of  palladium,  platinum,  and  gold  ;  and  to  ascertain 
how  far  they  agree,  and  in  what  they  differ,  as  to  the  laws  of  com- 
bination to  which  these  compounds  are  subjected.  He  commences 
with  the  investigation  of  the  compounds  of  palladium,  employing  for 
that  purpose  a  portion  of  that  metal  with  which  he  was  furnished  by 
the  Royal  Society  out  of  the  quantity  bequeathed  to  the  Society  by 
the  late  Dr.  Wollaston.  He  describes  the  mode  of  obtaining  the 
protoxide  of  palladium,  and  enters  into  the  analysis  of  the  hydrated 
oxide,  the  black  suboxide,  and  the  true  basic  carbonate  of  that  metal ; 
detailing  their  properties  and  the  formulae  which  express  their  mode 
of  composition.  The  chlorides  of  palladium  form  the  next  subject  of 
inquiry  ;  and  the  author  concludes  from  his  experiments  that  the  loss 
of  chlorine  which  the  protochloride  undergoes,  when  kept  for  some 


"Royal  Society.  51 

time  in  a  state  of  fusion  at  a  red  heat,  is  perfectly  definite ;  and  also 
that  the  loss  represents  one  half  of  the  chlorine  which  the  salt  con- 
tains. But  in  the  double  salts  formed  by  the  protochloride  of  pal- 
ladium with  the  chlorides  of  the  alkaline  metals,  he  finds  that  the 
similarity  of  constitution  usually  occurring  between  the  compounds 
of  ammonium  and  potassium  is  violated.  From  his  analysis  of  the 
oxychloride  of  palladium  the  author  concludes  that  it  is  quite  ana- 
logous to  the  ordinary  oxychloride  of  copper.  He  then  examines  a 
variety  of  products  derived  from  the  action  of  a  solution  of  caustic 
potash  on  solutions  of  ammonia-chlorides  of  potassium.  Their 
properties  he  finds  to  indicate  analogies  between  palladium  and 
other  metals,  whose  laws  of  combination  are  better  known.  The 
sulphate,  the  ammonia-sulphates,  the  nitrates,  and  the  ammonia-ni- 
trates of  palladium,  and  lastly,  the  double  oxalate  of  palladium  and 
ammonium,  are,  in  like  manner,  subjected  to  examination  in  a  de- 
tailed series  of  experiments. 

The  second  section  of  the  paper  relates  to  the  compounds  of  pla- 
tinum, and  comprehends  researches  on  the  composition  of  the  proto- 
chloride of  platinum ;  on  the  action  of  ammonia  on  biniodide  of  pla- 
tinum ;  and  on  the  action  of  ammonia  on  the  perchloride  of  plati- 
num; in  which  the  properties  of  these  substances  are  detailed  and 
the  formulae  expressing  their  composition  deduced. 

There  was  also  read,  "Magnetic  Observations  made  at  Prague  for 
September  1841."  ByC.Kreil.  Communicated  by  S.  Hunter  Christie, 
Esq.,  M.A.,  Sec.  R.S. 

April  7. — The  following  papers  were  read,  viz. — 

Meteorological  Observations,  taken  in  conformity  with  the  Re- 
port drawn  up  by  the  Committee  of  Physics,  including  Meteorology, 
for  the  guidance  of  the  Antarctic  Expedition,  as  also  for  the  fixed 
Magnetic  Observatories,  transmitted  to  the  Society  by  the  Lords 
Commissioners  of  the  Admiralty  and  the  Master-General  of  the  Ord- 
nance, and  communicated  by  the  Council,  were  read  ;  viz. — 

1.  "  Meteorological  Observations  taken  on  board  H.M.  Ship  Ere- 
bus, for  August  and  September  1841."  By  Capt.  James  Clark  Ross, 
R.N.,  F.R.S.,  Commander  of  the  Expedition.     {Forms  1  and  2.) 

2.  "  Meteorological  Observations  taken  by  the  Niger  Expedition, 
for  May,  June  and  July  1841." 

3.  "  Meteorological  Observations  taken  at  the  Magnetic  Observa- 
tory, Ross-Bank,  Van  Diemen's  Land,  for  November  and  December 
1840,  and  January,  February  and  March  1841."     {Forms  1  and  2.) 

4.  "  Meteorological  Observations  taken  at  the  Magnetic  Observa- 
tory, Cape  of  Good  Hope,  for  October  and  November  1841."  By 
F.  Eardley  Wilmot,  Esq.,  Lieut,  in  the  Royal  Artillery.  {Forms  1 
and  2.) 

5.  "  Meteorological  Observations  taken  at  the  Magnetic  Observa- 
tory, Toronto,  for  January,  February,  March,  April  and  May  1841." 
By  C.  W.  Younghusband,  Esq.,  Lieut,  in  the  Royal  Artillery.  {Forms 
1  and  2.) 

6.  "  Of  the  ultimate  distribution  of  the  Air-passages,  and  of  the 
modes  of  formation  of  the  Air-cells  of  the  Lungs."  By  William  Addi- 

E2 


52  Royal  Society. 

son,  Esq.,  F.L.S.,  Surgeon,  Great  Malvern.      Communicated  by 
R.  B.  Todd,  M.D.,  F.R.S. 

After  reciting  the  various  opinions  which  have  prevailed  among 
anatomists  regarding  the  manner  in  which  the  bronchial  tubes  ter- 
minate, whether,  as  some  suppose,  by  cells  having  free  communica- 
tion with  one  another,  or,  as  others  maintain,  by  distinct  and  sepa- 
rate cells  having  no  such  intercommunication,  the  author  states  that 
having  been  engaged  in  investigating,  with  the  aid  of  the  micro- 
scope, the  seat  and  nature  of  pulmonary  tubercles,  he  could  never 
discover,  in  the  course  of  his  inquiry,  any  tubes  ending  in  a  cul-de- 
sac  ;  but,  on  the  contrary,  always  saw,  in  every  section  that  he  made, 
air-cells  communicating  with  each  other.  He  concludes  from  his 
experiments  and  observations,  that  the  bronchial  tubes,  after  dividing 
dichotomously  into  a  multitude  of  minute  branches,  which  pursue 
their  course  in  the  cellular  interstices  of  the  lobules,  terminate,  in 
their  interior,  in  branched  air-passages,  and  in  air-cells  which  freely 
communicate  with  one  another,  and  have  a  closed  termination  at  the 
boundary  of  the  lobule.  The  apertures  by  which  these  air-cells  open 
into  one  another  are  termed  by  the  author  lobular  passages :  but  he 
states  that  the  air-cells  have  not  an  indiscriminate  or  general  inter- 
communication throughout  the  interior  of  a  lobule,  and  that  no  ana- 
stomoses occur  between  the  interlobular  ramifications  of  the  bron- 
chiae  themselves ;  each  branch  pursuing  its  own  independent  course 
to  its  termination  in  a  closed  extremity.  Several  drawings  of  the 
microscopical  appearances  of  injected  portions  of  the  lungs  accom- 
pany this  paper. 

April  14. — A  paper  was  read,  entitled,  "  Remarks  on  the  probable 
natural  causes  of  the  Epidemic  Influenza  as  experienced  at  Hull  in 
the  year  1833 ;  with  a  delineation  of  the  Curves  of  the  maximum, 
the  mean,  and  the  minimum  Temperatures  in  the  shade,  and  the 
maximum  Temperature  in  the  sun's  rays  at  Hull,  during  the  years 
1823  and  1833."  By  G.  H.  Fielding,  M.D.  Communicated  by  the 
Rev.  Wm.  Buckland^  D.D.,  F.R.S. 

The  meteorological  causes  to  which  the  author  ascribes  the  sudden 
accession  of  the  influenza  at  Hull,  and  its  continuance  from  the  26th 
of  April  to  the  28th  of  May  1833,  are,  first,  the  unusually  cold 
weather  during  March,  and  also  the  cold  and  wet  which  prevailed 
during  April  in  the  same  year :  secondly,  the  sudden  rise  of  tem- 
perature, amounting  to  21  of  Fahr.,  which  occurred  in  a  few  hours 
on  the  26th  of  April :  and  thirdly,  the  continuance,  through  May, 
of  extreme  vicissitudes  of  temperature  between  the  day  and  the 
night ;  the  burning  heat  of  the  days  and  the  cold  thick  fogs,  with 
easterly  winds,  commencing  generally  about  sunset,  and  prevailing 
during  the  night. 

A  paper  was  also  read,  entitled,  "  Report  of  a  remarkable  appear- 
ance of  the  Aurora  Borealis  below  the  Clouds."  By  the  Rev.  James 
Farquharson,  LL.D.,  F.R.S.,  Minister  of  Alford. 

The  phenomenon  recorded  in  this  paper  occurred  on  the  night  of 
the  24th  of  February  1842,  when  a  remarkable  aurora  borealis  was 
seen  by  the  author  apparently  situated  between  himself  and  lofty 


Royal  Society.  53 

stratus  clouds,  which  extended  in  long  parallel  belts  with  narrow 
intervals  of  clear  sky  in  a  direction  from  north-west  to  south-east. 
The  author  gives,  in  detail,  the  particulars  of  his  observations*. 

April  21. — The  following  papers  were  read : — 

1.  "  On  the  Organic  Tissues  in  the  bony  structure  of  the  Coral- 
lidae."  By  J.  S.  Bowerbank,  Esq.  Communicated  by  Thomas  Bell, 
Esq.,  F.R.S.,  was  in  part  read. 

"  Papers  from  the  several  Magnetic  Observatories  established  in 
India,  addressed  to  the  Secretary  of  the  Royal  Society,  by  direction 
of  the  Honourable  East  India  Company."  Communicated  by  P.  M. 
Roget,  M.D.,  Sec.  R.S. 

1.  From  the  Magnetic  Observatory  at  Madras: — 

Magnetic  and  Meteorological  Observations  for  October,  Novem- 
ber and  December  1841;  as  also  for  January  1842. 

Term-day  Observations  for  October  and  November,  and  Curves 
for  August,  September,  October  and  November  1841. 

Observations  of  the  Direction  and  Force  of  the  Wind,  and  the 
state  of  the  Sky,  during  October  and  November  1841. 

Extraordinary  Magnetic  Curves  for  September,  October  and  De- 
cember 1841. 

2.  From  the  Magnetic  Observatory  at  Singapore : — 
Magnetic  Observations  from  March  to  October  1841,  with  Curves 

for  the  same  period. 

Anemometer  Curves  for  March,  April,  May,  June,  July,  August, 
September  and  October  1841. 

Abstracts  of  the  Weather  for  June,  July,  August  and  September 
1841;  as  also  the  Determination  of  the  Temperature  at  Singapore. 

Tide  Reports  for  April,  May  and  June  1841. 

3.  From  the  Magnetic  Observatory  at  Simla: — 

Abstracts  of  Magnetic  and  Meteorological  Observations  for  No- 
vember and  December  1841. 

Magnetic  Observations  for  February,  May,  October  and  Decem- 
ber 1841,  with  Curves  for  the  same  period. 

April  28. — A  paper,  entitled,  "On  the  Organic  Tissues  in  the  bony 
structure  of  the  Corallidae."  By  J.  S.  Bowerbank,  Esq.,  F.G.S.,  com- 
municated by  Thomas  Bell,  Esq.  F.R.S.,  was  resumed  and  concluded. 

The  author  submitted  small  portions  of  nearly  seventy  species  of 
bony  corals  to  the  action  of  diluted  nitric  acid,  and  thus  obtained 
their  animal  tissue,  freed  from  calcareous  matter,  and  floating  on 
the  surface  of  the  fluid  in  the  form  of  a  delicate  flocculent  mass. 
By  the  aid  of  the  microscope,  this  mass  was  found  to  be  pervaded 
by  a  complex  reticulated  vascular  tissue,  presenting  numerous  rami- 
fications and  anastomoses,  with  lateral  branches  terminating  in 
closed  extremities.  There  were  also  found,  interspersed  among 
these,  another  set  of  tubes,  of  larger  diameter  than  the  former,  and 
provided,  in  many  places,  with  valves ;  the  branches  from  these 
larger  vessels  occasionally  terminate  in  ovoid  bodies,  having  the 
appearance  of  gemmules  or  incipient  polypes.  In  other  cases, 
masses  of  still  larger  size,  of  a  more  spherical  shape,  and  of  a 

[*  A  notice  of  a  former  paper  on  the  Aurora  by  Mr.  Farquharson  will  be 
found  in  Phil.  Mag.,  Second  Series,  vol.  v.  p.  304.— Edit.] 


54  Royal  Society. 

brown  colour,  were  observed  attached  to  the  membrane,  and  con- 
nected with  each  other  by  a  beautiful  network  of  moniliform  fibres. 
Numerous  siliceous  spicula,  pointed  at  both  extremities  and  exceed- 
ingly minute,  were  discovered  in  the  membranous  structure  of  se- 
veral corals  ;  and  also  other  spicula  of  larger  size,  terminated  at 
one  extremity  in  a  point,  and  at  the  other  in  a  spherical,  head ;  a 
form  bearing  a  striking  resemblance  to  that  of  a  common  brass  pin. 

Besides  these  spicula,  the  author  noticed  in  these  membranous  tis- 
sues a  vast  number  of  minute  bodies,  which  he  regards  as  identical 
with  the  nuclei  of  Mr.  Robert  Brown,  or  the  cytoblasts  of  Schleiden. 

A  paper  was  also  in  part  read,  entitled,  "  Sixth  Letter  on  Voltaic 
Combinations,"  addressed  to  Michael  Faraday,  Esq.,  D.C.L.,  F.R.S., 
&c.  By  John  F.  Daniell,  Esq.,  For.  Sec.  R.S.,  Professor  of  Che- 
mistry in  King's  College,  London,  &c. 

May  5. — The  reading  of  a  paper,  entitled,  ""Sixth  Letter  on  Voltaic 
Combinations,"  addressed  to  Michael  Faraday,  Esq.,  D.C.L.,  F.R.S., 
Fullerian  Professor  of  Chemistry  in  the  Royal  Institution  of  Great 
Britain,  &c,  by  John  Frederic  Daniell,  Esq.,  Foreign  Sec.  R.S., 
Professor  of  Chemistry  in  King's  College,  London,  was  resumed 
and  concluded. 

The  purport  of  this  letter  is  to  follow  the  consequences  of  the  law 
of  Ohm,  and  the  expressions  which  result  from  it,  relative  to  the 
electromotive  force,  and  to  the  resistances  in  the  course  of  a  voltaic 
circuit ;  to  apply  this  theory  to  the  verification  of  the  conclusions 
which  the  author  had  formerly  deduced  from  his  experiments ;  and 
to  suggest  additional  experiments  tending  to  remove  some  obscu- 
rities and  ambiguities  which  existed  in  his  former  communications. 
In  following  out  these  principles,-  the  author  is  led  to  offer  various 
practical  remarks  on  the  different  forms  of  voltaic  batteries  which 
have  been  proposed  with  a  view  either  to  the  advancement  of  our  theo- 
retical knowledge  of  the  science,  or  to  the  service  of  the  arts.  The 
author  enters  more  particularly  into  an  explanation  of  the  principles 
on  which  the  cylindric  arrangement  of  the  battery  he  has  intro- 
duced is  founded,  which  appear  to  him  to  have  been  greatly  misun- 
derstood. The  formulae  and  the  calculations  which  form  the  body 
of  this  paper  are  not  of  a  nature  to  admit  of  being  reported  in  the 
present  abstract*. 

May  12. — "  On  the  Rectification  and  Quadrature  of  the  Spheri- 
cal Ellipse."  By  James  Booth,  Esq.,  M.A.,  Principal  of  Bristol  Col- 
lege. Communicated  by  John  T.  Graves,  of  the  Inner  Temple,  Esq., 
M.A.,  F.R.S. 

The  author,  at  the  commencement  of  this  paper,  adverts  to  a 
rather  complex  discussion  of  a  portion  of  the  subject  of  his  inquiry 
by  M.  Catalan,  published  in  the  Journal  de  Mathematiques,  edited 
by  M.  Liouville. 

He  then  proceeds  to  establish  two  fundamental  theorems,  appli- 

[*  Abstracts  of  Prof.  Daniell's  preceding  five  letters  on  Voltaic  Combi- 
nations have  already  been  given  in  Phil.  Mag.,  Third  Series;  see  vol.  xv. 
p.  312.  Dr.  Martin  Barry's  paper  on  Fibre,  also  read  May  5,  will  be  no- 
ticed in  a  future  Number,  together  with  Lieut.-Col.  Yorke's  on  the  Effect 
of  the  Wind  on  Barometers,  read  May  12th.— Edit.] 


Royal  Society.  5$ 

cable  to, — 1st,  the  quadrature,  and  2nd,  the  rectification  of  the  sphe- 
rical ellipse. 

1st.  The  quadrature  of  the  spherical  ellipse  is  reduced  to  the 
calculation  of  a  complete  elliptic  function  of  the  third  order,  whose 
parameter  and  modulus  are  quantities  essentially  related  to  the 
cone;  its  parameter  being  the  square  of  the  eccentricity  of  the 
ellipse,  whose  plane  is  at  right  angles  to  the  axis  of  the  cone,  and 
its  modulus  being  the  sine  of  the  semi-angle  between  the  focals. 

2nd.  The  rectification  of  the  spherical  ellipse  is  made  to  depend 
on  a  complete  elliptic  function  of  the  third  order,  whose  parameter 
is  the  same  as  in  the  preceding  case,  but  whose  modulus  is  the  sine 
of  the  angle  between  the  planes  of  the  elliptic  base  and  of  one  of 
the  circular  sections. 

The  author  then  proceeds  to  establish  a  remarkable  relation  be- 
tween the  area  of  a  given  spherical  ellipse  and  the  length  of  the 
spherical  ellipse  generated  by  the  intersection  of  the  supplemental 
cone  with  the  same  sphere. 

He  shows  that  if  there  are  two  concentric  supplemental  cones  cut 
by  the  surface  of  a  concentric  sphere, — 1st,  the  sum  of  their  spherical 
bases,  together  with  twice  their  lateral  surfaces,  is  equal  to  the  sur- 
face of  the  sphere ;  2nd,  the  difference  of  their  spherical  bases  is 
equal  to  twice  the  difference  of  their  lateral  surfaces. 

Hence,  also,  he  deduces  a  remarkable  theorem,  viz.  the  sum  of 
the  spherical  bases  of  any  cone  whose  principal  angles  are  supple- 
mental, cut  by  a  sphere,  together  with  twice  the  lateral  surface  of 
the  cone  comprised  within  the  sphere,  is  equal  to  the  surface  of  the 
sphere. 

The  author  then,  alluding  to  some  researches  of  Professor 
MacCullagh  and  of  the  Rev.  Charles  Graves,  Fellow  of  Trinity  Col- 
lege, Dublin,  proceeds  to  give  a  simple  elementary  proof  of  a  well- 
known  formula  of  rectification,  and  thence  deduces  some  remark- 
able properties  of  the  tangent  at  that  point  of  the  ellipse,  which  is 
termed  by  him  the  point  of  rational  section. 

Assuming  the  properties  of  the  plane  ellipse,  he  proceeds  to  show 
that  a  similar  formula  of  rectification  holds  for  any  curve  generated 
by  the  intersection  of  a  spherical  surface  with  a  concentric  cone  of 
any  order.  He  goes  on  to  develope  a  series  of  properties  of  the 
spherical  ellipse,  bearing  a  striking  analogy,  as  indeed  might  have 
been  expected,  to  those  of  the  plane  curve.  Thus  he  establishes  a 
point  of  rational  section  as  in  the  plane  ellipse,  shows  that  the  tan- 
gent arc  is  at  this  point  a  minimum,  and  developes  some  other  cu- 
rious analogies.  It  is  a  simple  consequence  of  his  formula  that  the 
spherical  elliptic  quadrant  may  be  divided  into  two  arcs  whose  dif- 
ference shall  be  represented  by  an  arc  of  a  great  circle.  This 
theorem,  previously  obtained  by  M.  Catalan,  is  analogous  to  that  of 
Fagnani,  which  shows  that  the  difference  of  two  plane  elliptic  arcs 
may  be  represented  by  a  straight  line. 

The  author  concludes  by  reducing  the  quadrature  of  the  surface 
of  a  cone  of  the  second  degree,  bounded  by  a  plane  perpendicular 
to  the  axis,  to  the  determination  of  a  complete  elliptic  function  of 
the  second  order. 


56  Royal  Astronomical  Society. 

ROYAL  ASTRONOMICAL  SOCIETY. 
(Continued  from  vol.  xix.  p.  584.) 
Nov.  12,  1841. — The  following  communications  were  read  : — 
I.  On  the  Longitude  of  Dr.  Lee's  Observatory  at  Hartwell. 
The  longitude  of  this  observatory  was  assumed  from  various  au- 
thorities to  be  3m  20s* 6  west  from  the  Royal  Observatory  at  Green- 
wich, by  the  late  Mr.  Epps,  for  some  time  after  his  arrival  at  Hart- 
well.    These  authorities  appear  to  have  been  as  follows  :        m      s 
Capt.  Smyth,  by  means  of  two  trips  with  a  chronometer  "I    „  -1 - 

from  Bedford  Observatory J 

By  the  moon's  culminations  as  computed  by  Mr.  Riddle         19-9 

Mr.  Epps,  by  chronometers     21*7 

Ditto   20-7 

Mean  longitude 3  20-6 

The  mean  of  these  determinations  was  naturally  supposed  by  Mr. 
Epps  to  be  very  near  the  truth.  In  October  1838  this  mean  result 
was  found,  however,  to  differ  considerably  from  the  difference  of 
meridians  as  determined  by  twelve  chronometers,  taken  by  Mr.  Dent 
from  the  Royal  Observatory  (which  was  3m  24s,46).  It  was  evi- 
dent, therefore,  that  there  was  either  an  error  of  nearly  four  seconds 
of  time  in  the  longitude  of  Hartwell,  as  previously  assumed,  or  in 
the  observations  made  there  on  this  occasion  to  determine  the  error 
of  the  clock  with  which  the  chronometers  were  compared.  A  care- 
ful recomputation  of  the  observations,  as  recorded  in  the  Hartwell 
transit  books,  was  therefore  made,  and  the  result  (as  far  as  the  re- 
ductions were  concerned)  was  found  to  be  correct. 

A  reference  was  then  had  to  Aylesbury  church  spire,  the  position 
of  which  had  been  determined  by  the  Trigonometrical  Survey.  This 
was  done  by  means  of  an  estimated  distance  of  the  spire  from  the 
Hartwell  Observatory,  taken  from  a  county  survey,  and  the  observed 
azimuth  of  the  former  from  the  observatory.  This  gave  a  result 
(3m  23s-07)  differing  2S*5  of  time  from  Mr.  Epps's  former  determi- 
nation, and  ls,5  from  that  obtained  from  Messrs.  Arnold  and  Dent's 
chronometers,  and  was  therefore  far  from  being  satisfactory. 

In  the  following  January  another  series  of  results  was  obtained 
by  means  of  ten  chronometers,  which  were  taken  by  Mr.  Dent  as 
before,  from  the  Royal  Observatory  to  Hartwell,  on  the  6th  of  that 
month,  and  the  comparisons  made  with  the  transit  clock  at  the  latter 
place  on  the  same  day.  The  chronometers  were  brought  back  to  the 
Royal  Observatory  on  the  9th  following.  The  difference  of  meri- 
dians by  these  observations  was  3m  24s-06. 

Other  results  were  also  obtained  by  means  of  chronometers  taken 
from  the  Royal  Hospital  Schools  at  Greenwich  to  Hartwell  Obser- 
vatory ;  and,  in  reference  to  these  results,  as  well  as  to  those  before 
obtained,  Mr.  Epps  observes,  in  a  letter  to  Mr.  Fisher,  "The  results 
agreeing  so  well  with  the  former,  I  think  we  may  conclude  that 
3m  24s,2  (as  you  have  already  noticed)  is  extremely  near  the  truth. 
This  may  be  called  the  mean  result  of  thirty  chronometrical  deter- 
minations. I  may  remark  to  you,  that  my  observations  for  time  are 
made  with  as  much  attention  as  possible  to  the  state  of  the  transit 


Royal  Astronomical  Society.  57 

instrument ;  viz.  that  it  works  with  no  apparent  error  in  collimation, 
nor  level  error,  but  correcting  as  occasion  may  require  for  azimuthal 
deviation.  With  the  exception,  therefore,  of  minute  differences  in  the 
right  ascensions  of  the  stars  by  which  the  clock-errors  were  deter- 
mined, and  some  trifling  optical  defects,  I  conclude  that  nothing  of 
importance  can  be  urged  against  the  mean  of  all  the  results.  In- 
deed, all  the  observations  respecting  the  chronometrical  comparisons 
are  plain  and  straightforward  matters  of  fact  in  conjunction  with  the 
transit  observations,  as  recorded  in  the  observation  books." 

The  error  in  the  former  assumed  longitude  being  now  fully  con- 
firmed by  so  many  chronometrical  results,  it  was  resolved  to  connect 
in  a  more  accurate  manner  than  before  the  position  of  Aylesbury 
spire  with  that  of  the  observatory  at  Hartwell  by  actual  measurement 
and  triangulation ;  since  it  was  possible  that  an  error  might  have  oc- 
curred so  as  to  have  caused  the  discrepancy  observed  between  the 
chronometrical  longitude  and  that  obtained  by  the  Trigonometrical 
Survey.  This  was  done  in  April  1840,  and  the  result  was  nearly  iden- 
tical with  that  previously  deduced  by  means  of  the  county  survey. 

As  there  is  a  considerable  error  in  the  longitude  of  this  spire  as 
given  in  the  third  edition  of  the  Requisite  Tables,  Mr.  Yolland,  of  the 
Ordnance  Map  Office,  very  kindly  undertook  the  recomputation  of  its 
geographical  position  from  the  original  data  of  the  Trigonometrical 
Survey,  and  found  it  to  be  as  follows : —  0      t       „ 

Latitude      '. .    5149     10     North. 

Longitude 0  48  50-15  West. 

In  time   3m  15s<34 

From  this  corrected  position  of  the  spire,  we  have  the  following 
for  the  position  of  the  observatory  at  Hartwell : — 

Latitude 51°  48'  14"-8  North. 

Longitude     3m  22s-57  West. 

Final  results  for  difference  of  meridians  : —  m    s 

By  the  chronometrical  determinations 3  24*26 

By  Aylesbury  spire,  as  determined  by  the  Trigonome- 1    .,  99.k7 
trical  Survey J  J 

Difference 1*69 

II.  Observations  of  the  Beginning  and  Termination  of  the  Solar 
Eclipse  of  July  18,  1841,  at  Aberdeen.  By  Charles  Crombie,  Esq. 
Communicated  by  George  Innes,  Esq. 

The  eclipse  was  observed  in  the  garden  attached  to  Mr.  Crombie's 
residence,  which  is  a  short  distance  from  the  Marischal  College. 
The  instrument  used  was  a  2£  feet  achromatic  telescope,  with  a 
power  of  about  thirty-six ;  and  the  times  were  taken  with  a  pocket 
chronometer,  whose  rate  was  determined  by  two  comparisons  with  a 
clock  belonging  to  Mr.  Innes,  and  the  error  by  several  altitudes  of 
the  sun. 

The  Aberdeen  mean  solar  times  of  the  beginning  and  ending  of 
the  eclipse,  resulting  from  the  observations,  are — 

h      m       s 

For  the  beginning 2  17  48*7 

And  for  the  ending 2  58  10'2 


58  Royal  Astronomical  Society. 

III.  Observation  of  the  Lunar  Occultation  of  Venus  on  September 
11,  1841,  at  Mr.  Bishop's  Observatory,  in  the  Regent's  Park. 

The  occultation  of  Venus  by  the  moon  was  observed  here,  but 
not  under  favourable  circumstances.  The  morning  was  clear,  but 
the  wind  easterly.  The  equatoreal  telescope  was  charged  with  a 
power  of  105.  Venus  was  badly  defined  in  general,  the  air  being 
in  a  very  disturbed  state.  The  enlightened  edge  of  the  moon  com- 
pletely hid  the  planet  at  about  18h  31m  21s,  Greenwich  mean  astro- 
nomical time.  The  time  was  not  accurately  noted,  the  observer's 
attention  being  principally  directed  to  the  phenomena  of  the  occul- 
tation. No  projection  on  the  moon's  limb,  nor  any  distortion  of  the 
form  of  Venus,  was  perceivable.  The  edge  of  the  moon  was  well 
seen,  and  sharply  defined  on  the  planet's  disc. 

The  commencement  of  the  reappearance  at  the  unenlightened  edge 
was  not  well  caught,  the  planet  becoming  visible  at  some  distance 
from  the  centre  of  the  field.  This  being  instantly  rectified,  the  dark 
edge  was  well  seen  on  the  planet,  which  did  not  appear  in  the  least 
distorted.  The  reappearance  was  complete  at  about  19h  41m  54s, 
Greenwich  mean  time,  and  was  observed  with  the  power  105.  The 
air  had  become  very  smoky,  and  vision  was  extremely  bad. 

IV.  Notice  of  the  Occultation  of  Venus  on  the  morning  of  the 
12th  of  September,  1841.  Observed  at  Malta  by  Capt.  Basil  Hall, 
R.N.     Communicated  by  Capt.  Beaufort,  R.N. 

"  The  beginning  of  this  interesting  occultation  was  observed  at 
Valetta  within  a  second  of  time,  I  think  I  may  venture  to  say.  An 
unlucky  cloud  prevented  my  observing  the  planet's  reappearance. 
Telescope  magnifying  sixty  times. 

"  The  following  are  the  times  by  chronometer : — 
First  contact  of  the  north  limb  of  Venus  with  the 

south  limb  of  the  moon  (civil  reckoning) 

Instant  when  the  centre  of  Venus  appeared  cut  by "] 

the  enlightened  limb  of  the  moon,  as  nearly  as  I  >6  46  26 

could  judge J 

Contact  of  the  eastern,  or  enlightened,  limb  of  Venus  1  „    >fi  "\(\-c\ 
with  the  eastern,  or  enlightened,  limb  of  the  moon  J 

Chronometer  slow  of  Malta  mean  time 1     6  33*2 

Mean  time  at  Malta  of  the  disappearance  of  the  "1 

eastern  limb  of  Venus  behind  the  east  limb  of  >7  53     9*2 

the  moon    J 

Difference  of  longitude 58  xl*8 

Mean  time  at  Greenwich  of  the  disappearance  of  1  fi  --     ,.. 

the  eastern  limb  of  Venus  behind  the  moon. ...  J 
"  The  time  was  ascertained  by  equal  altitudes  of  the  sun,  and,  I 
think,  may  be  considered  correct  to  about  a  second.  The  differ- 
ence of  longitude  is  taken  from  the  Table  No.  8.  in  Lieut.  Raper's 
recently  published  work,  in  which  you  will  observe  that  the  obser- 
vatory (which  is  no  longer  an  observatory)  on  the  palace  is  placed 

in    14°  30'  42"  =  58m  2s-8.     But 

my  house  lies  west  of  the  palace    1  0 

Consequently  the  difference  of  longitude  is 58     1  '8 


|  6  45  54 


Royal  Astronomical  Society. 


59 


"  The  latitude  of  my  house  is  the  same  as  that  of  the  observatory, 
viz.  35°  53'  54",  as  given  by  Lieut.  Raper ;  but  I  have  not  yet  had 
an  opportunity  of  verifying  this  point. 

"  On  the  voyage  to  Malta  from  England,  and  since  my  arrival 
here,  I  have  had  ample  means  of  examining  the  work  above  alluded 
to ;  and  I  feel  it  right  to  say, — and  I  hope  you  will  communicate 
my  testimony  (such  as  it  is  worth)  to  the  Astronomical  Society,  in 
favour  of  the  book  of  my  highly  valued  friend,  their  secretary, — I 
have  gone  over  almost  every  part  of  the  Practice  of  Navigation,  and 
some  of  the  parts  a  great  many  times,  and  I  can  say  without  quali- 
fication, that  I  am  acquainted  with  no  work  so  well  adapted  for  the 
use  of  sailors,  none  so  luminous  and  precise  in  its  style,  nor  so  sim- 
ple in  its  use.  The  tables,  too,  are  well  arranged  and  of  very  ready 
application,  in  consequence  not  only  of  the  distinctness  of  the  pre- 
cepts, but  the  good  selection  of  illustrative  examples.  It  is  much 
to  be  desired  that  Lieut.  Raper  should  publish  his  second  volume, 
for  such  works  contribute  greatly  to  the  improvement  of  practical 
navigation,  not  merely  by  the  information  they  furnish,  but  by  rais- 
ing the  standard  of  accuracy,  and  teaching  that  even  by  moderate, 
but  well-directed,  exertions,  any  ship  may  be  navigated  with  far 
more  certainty  and  speed  than  by  the  ordinary  and  loose  methods 
still,  unfortunately,  too  much  in  use  afloat." 

V.  Observations  of  Bremicker's  Comet  made  with  the  Equatoreal 
Instrument  of  the  Observatory  of  Padua.     By  M.  Santini. 

As  soon  as  the  notice  of  this  discovery  was  received,  the  comet 
was  immediately  sought  for  at  the  Observatory  of  Padua ;  but  clouds 
and  the  light  of  the  moon  prevented  it  from  being  seen  till  the  even- 
ing of  the  22nd  of  November  :  it  was  extremely  faint,  and  presented 
itself  under  the  appearance  of  a  light  mass  of  vapour  faintly  illumi- 
nated, without  sensible  trace  of  a  nucleus.  It  was  observed  till  the 
evening  of  the  27th  of  November  ;  after  which  time  other  occupa- 
tions hindered  M.  Santini  from  making  further  observations  of  it  till 
the  1st  of  December.  After  this  time  the  clouds  and  the  light  of  the 
moon  caused  him  to  give  up  the  hope  of  seeing  it  again. 


Day, 

Mean  Time 

Apparent  R.A. 

ApparentDeclin. 

Comparison-Stars  from 

1840. 

at  Padua. 

of  the  Comet. 

of  the  Comet. 

Piazzi's  Catalogue. 

h      m     g 

h    in        s 

O          /              il 

Nov.  23. 

9    3    6-5 

21  40  12-78 

+55  54  37-1 

Piazzi  xxi.  385. 

24. 

7  26    8-1 
7  51    5-4 

21  47  24-58 
21  47  31-92 

55  25    1-8 
55  24  31-8 

j-Dittoxxi.373&385. 

25. 

7    1  33-4 

21  54  57-55 

54  51  451 

1 

7  32    49 

21  55    4-13 

54  50  47-1 

\  Ditto  xxi.  54  &  92. 

8    5  56-2 

21  55    6-19 

54  49    4-1 

J 

26. 

7  13  137 

22     2  35-76 

54  15  23-4 

1 

7  36  40-5 

22    2  41*47 

54  15    95 

\  Ditto. 

7  58  32-0 

22     2  43-06 

54  14    6-5 

J 

27- 

7  33  31-0 

22  10  12-29 

53  36  56-0 

1 

7  56  38-6 

22  10  1695 

-  53  35  40-8 

\  Ditto  xxii. 92  &  137. 

8    8  34-7 

22  10  26-32 

+53  36  23-8 

i 

M.  Santini  has  computed  elements  of  the  parabolic  orbit  of  the 


60  Royal  Astronomical  Society. 

comet,  based  on  the  observation  made  at  Berlin  on  October  28,  com- 
municated to  astronomers  by  M.  Schumacher;  on  that  made  at 
Vienna  on  November  12  ;  and  on  the  mean  of  the  above  positions  of 
November  24. 

The  following  are  the  elements  derived  : — 
Perihelion  passage,  November,  15*25525 *,  Berlin  mean  time. 

o  / 

Long,  of  the  perihelion. .      23  42*5  from  the  true  equinox. 

Long,  of  the  node 248  47*7 

Inclination 58     5*05      ...  ... 

Motion  Direct. 
Log.  perihelion  dist.  =  0*16984 
perihelion  dist.  =  1*4786 

VI.  Introduction  to  a  Catalogue  of  1677  Stars  included  between 
the  Equator  and  10°  of  North  Declination,  observed  at  the  Royal 
Observatory  of  Padua.  By  M.  Santini.  Communicated  by  Sir 
J.  F.  W.  Herschel,  Bart. 

The  observations  of  the  stars  in  this  catalogue  were  made  with 
a  meridian  circle  constructed  by  Starke,  a  description  of  which  is 
to  be  found  in  the  fifth  volume  of  the  Transactions  of  the  Academy 
of  Padua.  The  object  of  M.  Santini  has  been  so  to  arrange  his  new 
catalogue  that,  at  every  eight  or  ten  minutes  of  right  ascension, 
there  should  be  found  in  each  parallel  of  declination  a  well-deter- 
mined star,  with  the  view  of  facilitating  the  comparisons  of  planets 
and  comets  with  neighbouring  stars,  by  means  of  micrometrical 
measurements. 

The  brightest  stars  that  could  be  found  were  chosen  for  this  pur- 
pose, very  few  being  admitted  which  are  below  the  eighth  magnitude. 
They  were  observed  for  convenience  of  reduction  in  contiguous 
groups,  in  such  a  manner  that  the  corrections  necessary  for  reducing 
them  to  the  mean  equinox  of  1840  might  be  applied  to  the  mean  of 
the  apparent  positions  observed,  for  the  mean  instant  of  the  series ; 
and  the  greater  number  of  the  stars  were  observed  three  times  in 
both  elements.  It  is  the  author's  intention  to  proceed  immediately 
with  similar  observations  of  stars  in  the  zone  extending  from  the 
equator  to  20°  of  south  declination  ;  and  he  invites  astronomers  to 
participate  in  his  labours  by  observing  some  other  zones. 

The  observed  right  ascensions  of  Bessel's  fundamental  stars  were 
compared  with  their  right  ascensions  given  in  the  Berlin  Ephemeris, 
for  obtaining  the  clock-correction ;  and  the  azimuthal  deviation  of 
the  instrument  was  obtained  by  the  superior  and  inferior  transits  of 
Polaris. 

The  polar  point  of  the  circle  was  obtained  by  observed  zenith 
distances  of  Polaris  and  the  same  fundamental  stars,  using  Carlini's 
Refraction  Tables,  and  the  apparent  declinations  of  the  Berlin  Ephe- 
meris. The  agreement  of  the  individual  results  both  for  clock  errors 
and  for  polar  point  was  in  general  highly  satisfactory.  To  obtain  the 
mean  places  for  1 840,  small  special  tables  were  used  similar  to  those 

*  In  the  manuscript  the  time  of  the  perihelion  passage  is  also  written 
3201-24525. 


London  Electrical  Society.  61 

employed  for  Bessel's  zones,  the  values  of  the  constants,  /,  g,  h,  i, 
G,  H,  of  the  Berlin  Ephemeris  being  adopted ;  and  in  the  annual 
variations  no  allowance  has  been  made  for  proper  motions  of  any  of 
the  stars.  

LONDON   ELECTRICAL   SOCIETY. 

Feb.  15,  1842.  The  papers  read  were, — 1st,  "On  the  Electrical 
relation  between  Plants  and  Vapours."  By  Mr.  Pine.  The  author,  still 
pursuing  the  same  path  as  that  traced  out  in  his  former  communica- 
tions, makes  copious  extracts,  from  various  quarters,  both  of  natural 
and  experimental  facts,  in  support  of  his  views  of  the  relation  be- 
tween the  subtle  fluid— electricity,  and  the  functions  of  vegetable 
life.     His  opmions  and  reasonings  are  worthy  of  examination. 

2nd,  "  Further  Observations  on  Electrotype  Manipulation — Depo- 
siting on  Plumbago — Electro-lace."     By  Charles  V.  Walker,  Esq., 
Hon.  Sec.     The  difficulty  attendant  on  the  reduction  of  copper  upon 
the  parts  of  plumbagoed  surfaces  most  remote  from  the  connect- 
ing wire,  is  obviated  by  a  very  simple  process.     One  or  more  fine 
leading  wires  are  twisted  round  the  main  wire,  and  made  to  abut 
upon  any  part  of  the  surface  where  the  reduction  has  not  occurred. 
The  value  of  this  apparently  trivial  piece  of  information  can  be  ap- 
preciated by  experimentalists  alone.     The  material,  to  which  the 
term  "  electro-lace"  has  been  given  (and  of  which  specimens  were 
before  the  Society),  is  obtained  by  depositing  copper  upon  net  or 
lace,  previously  prepared  with  wax  and  black-lead.     It  was  first  fa- 
bricated by  Mr.  Phillips  of  Cornwall,  in  lieu  of  the  copper  gauze  re- 
quired in  the  construction  of  Prof.  Grove's  modification  of  Smee's 
battery.     But  it  will  be  readily  seen  that  such  fabrics  as  gauze  and 
lace,  when  covered  with  copper,  and  plated  or  gilded,  may  be  intro- 
duced, in  a  multitude  of  ways,  into  the  construction  of  ornamental 
work,  where  at  present  embossed  and  perforated  cards  are  employed. 
3rd.  "  Nitrate  of  Soda  compared  with  other  Salts  employed  for 
Constant  Batteries."  By  Geo.  Mackrell,  Esq.,  Mem.  Elec.  Soc.  Cells 
were  excited  with  solutions  of  sulphate  of  copper,  bichromate  of 
potash,  nitrate  of  potash,  and  nitrate  of  soda.     The  palm  of  supe- 
riority, for  constancy  of  action,  is  awarded  to  the  latter :  in  addition 
to  this,  when  employed  for  electrotype  purposes,  it  throws  down 
more  copper  in  proportion  to  the  zinc  consumed,  than  either  of  the 
other  three  :  the  zinc  plates  (no  slight  advantage)  are  clean  when 
removed  from  the  battery. 

Mr.  Weekes's  Register  for  January  was  next  read.  At  the  sug- 
gestion of  several  scientific  correspondents,  with  a  view  to  promote 
the  objects  of  coincident  observation,  Mr.  Weekes  begins  the  Register 
of  1842  by  giving  the  readings  of  the  barometer  and  thermometer  at 
9  a.m.  instead  of  2  p.m. 

March  15. — The  papers  read  were, — 1st,  "Details  of  an  experi- 
ment, in  which  certain  insects,  known  as  the  Acarus  Crossii,  appeared, 
incident  to  the  long-continued  operation  of  a  voltaic  current  upon 
Silicate  of  Potash  within  a  close  atmosphere  over  mercury."  By 
W.  H.  Weekes,  Esq. 


62  London  Electrical  Society. 

After  alluding  to  the  original  experiment  of  Mr.  Crosse,  and  to 
the  objections  made  that  the  insects  might  have  sprung  from  ova 
in  the  atmosphere,  Mr.  Weekes  states  that  he  had  resolved  to  pro- 
vide against  such  contingencies.  This  he  effected  by  placing  the 
solution,  which  was  prepared  with  the  utmost  caution,  beneath  a 
bell-glass,  which  has  not  been  disturbed  from  Dec.  3rd,  1 840.  Late 
in  October  1841  the  first  insect  was  detected;  on  Nov.  27th  several 
were  seen  :  since  then  they  are  constantly  to  be  seen,  sometimes 
solitary,  at  other  times  in  pairs,  and  occasionally  three  or  four  to- 
gether. The  operation  was  conducted  in  the  dark,  light  being  only 
admitted  at  those  times  when  the  progress  was  under  examination. 
The  voltaic  current  was  from  a  short  series  of  Daniell's  battery. 
These  creatures  appear  to  love  darkness ;  for  on  the  admission  of  a 
ray  of  light  they  hasten  away  and  seek  hiding-places  in  the  recesses 
of  the  apparatus.  Simultaneously  with  this  another  arrangement 
was  made,  in  which  the  current  from  a  water  battery  was  made  to 
pass  through  a  solution  contained  in  a  bell-glass  of  oxygen.  Insects 
appeared  in  this  on  the  20th  Feb.  1842,  and  eight  or  ten  fine  vigo- 
rous Acari  were  visible.  This  is  but  a  brief  summary  from  a  very 
long  and  carefully  written  communication.  The  author  assumes 
nothing  ;  he  does  not  venture  to  theorise,  but  gives  a  plain  and  ex- 
plicit account  of  his  experiments  and  of  their  results.  The  operation 
is  still  going  on,  as  there  is  every  reason  to  expect  a  further  deve- 
lopment of  insect  life.  More  completely  to  preclude  objections,  he 
is  preparing  another  apparatus  in  which  nothing  but  glass,  metal, 
and  mercury  (distilled  from  its  sulphuret)  will  enter. 

2nd.  "  Note  on  Electro -tint,  and  on  etching  Daguerreotype 
Plates."    By  W.  G.  Lettsom,  Esq.,  M.E.S. 

This  note  was  illustrated  by  specimens  of  tints  produced  by  Prof. 
Von  Kobell  of  Munich,  and  Dr.  Berres  of  Vienna.  The  former 
has  improved  upon  his  original  process  of  electro-tint  by  a  method 
of  retouching  the  plates  and  then  reobtaining  others. 

3rd.  Extracts  of  a  letter  from  John  Samo,  Esq.,  of  Surinam, 
M.E.S. ,  containing  "  Information  respecting  the  Gymnotus  Electri- 
cus." 

Among  the  specimens  possessed  by  Mr.  Samo  were  two  in  one 
tub,  whose  relative  lengths  Were  SO  and  15|  in.  The  smaller  was 
missed,  and  it  was  found  that  the  other  had  swallowed  it.  He  soon 
however  cast  it  up,  and  in  the  space  of  a  few  hours  died.  On  post- 
mortem examination  it  was  found  that  the  stomach  was  considerably 
ruptured.  Mr.  Samo  mentions  that  the  report  that  a  certain  drug  is 
an  antidote  to  the  shock  of  the  Gymnotus  is  without  foundation. 

4th.  The  Secretary  then  communicated  to  the  Society  the  death 
of  the  London  Gymnotus,  which  has  from  time  to  time  furnished 
such  interesting  results  to  Prof.  Faraday,  Dr.  Schcenbein,  Mr.  Gassiot, 
and  others. 

5th.  "  On  Voltaic  Apparatus."   By  James  P.  Joule,  Esq.,  M.E.S. 

The  author  details  the  results  of  a  series  of  experiments  upon  local 
action,  and  upon  the  relative  intensities  of  several  voltaic  arrange- 
ments under  different  circumstances. 


London  Electrical  Society.  69 

6th.  Mr.  Weekes's  Electro-Meteorological  Register  for  February 
1 842  was  then  submitted  to  the  Society  *. 

May  17. — A  note  from  Mr.  Weekes  was  read,  stating  that,  when 
he  commenced  those  experiments,  during  which  insects  had  been 
developed,  he  made  similar  arrangements,  and  placed  tbem  in  va- 
rious parts  of  his  house,  without  allowing  the  voltaic  current  to  pass 
through  them ;  and  in  no  case,  by  the  strictest  examination,  could 
he  detect  any  appearance  of  the  insect. 

A  paper  "On  Lightning  Conductors,  and  on  the  Lightning. Flash 
which  struck  BrixtonChurch,"  by  CharlesV.Walker,Esq.,Hon.Sec, 
was  next  read.  Having  examined  the  steeple  of  this  church,  which  was 
struok  by  lightning  on  Sunday,  April  24th,  the  author  of  the  paper  saw 
in  the  damage  done  so  good  an  illustration  of  the  opinions  delivered  by 
Dr.  Faraday  a  few  days  previously  at  the  Royal  Institution,  that  he 
was  induced  to  survey  more  carefully  the  path,  and  report  it  to  the 
Society.  We  cannot,  without  drawings,  enter  into  detail  on  the  sub- 
ject, but  will  condense  the  general  conclusions  which  result  from  the 
investigation.  The  steeple  was  surmounted  by  a  copper  cross,  which 
formed  the  first  good  conductor :  the  second  was  twenty  feet  from 
this,  and  in  passing  along  the  interval  the  masonry  about  the  cross 
was  shivered  to  pieces,  and  the  cross  itself  was  forced  out  of  its 
place  :  the  third  conducting  series  was  twelve  feet  from  the  second : 
here  a  second  explosion  occurred,  and  the  base  of  a  column  three 
feet  in  diameter  was  shattered  and  the  column  rent.  How  strange 
it  is  that  such  occurrences  as  these  are  not  better  guarded  against ! 
If  the  "  lateral  discharge"  is  not  well  understood,  the  "  disruptive" 
is.  The  "  lateral  discharge"  occurred  in  the  belfry ;  and  Mr.  Walker 
showed  how  it  was  connected  with  that  property  of  electricity  which 
induces  it  to  take  the  widest  as  well  as  the  shortest  road.  He  ex- 
plained that,  when  the  fluid  is  passing  along  a  most  ample  conductor, 
some  of  it  will  enter  vicinal  conductors,  developing  light  and  heat. 
The  main  object  of  the  communication  was  to  trace  the  connexion 
between  the  experiments  of  the  Royal  Institution  and  the  pheno- 
mena illustrated  by  nature  on  a  large  scale.  He  then  explained  the 
method  of  conveying  the  fluid  safely  and  tranquilly  into  these  vicinal 
conductors,  by  forming  metallic  communications  between  them  and 
the  lightning  rod ;  otherwise  a  lightning  rod  may  become  a  most 
dangerous  enemy  instead  of  a  trustworthy  protector. 

Extracts  of  Notes  from  the  Rev.  Mr.  Lockey,  Mr.  Clarke  and  Mr. 
Mayo  were  read,  containing  valuable  additions  to  our  present  know- 
ledge on  Electrotype  Manipulation.  Mr.  Lockey  introduces  black- 
lead  in  his  composition  moulds,  and  Mr.  Mayo  flake-white.  The 
moulds  with  the  latter  were  exhibited,  and  were  superior  to  any  we 
have  seen.  A  copper  medal,  with  a  silver  surface  for  the  design,  by 
Mr.  Clarke.was  exhibited.     Mr.  Weekes's  Register  was  then  read. 

June  21st. — "  A  Notice  on  Native  Malleable  Copper,"  by  John 
A.  Phillips,  Esq.,  of  St.  Austell,  was  read,  in  which  the  author  states 
that  copper  in  this  form,  as  well  as  arborescent  and  moss  copper,  is 
produced  by  an  action  in  principle  the  same  as  that  artificially  em- 

*  The  proceedings  for  April  will  be  noticed  in  a  future  Number. 


64f  Royal  Irish  Academy, 

ployed  in  the  electrotype  process.  Several  mineralogical  specimens 
were  submitted  to  the  Society.  A  long  and  highly  interesting  paper 
was  then  read,  "  On  the  Transfer  of  Mineral  Substances,  through 
various  Fluids,  by  Electric  Agency,"  by  Andrew  Crosse,  Esq., 
Mem.  Elec.  Soc.  The  first  experiment  related  in  this  paper  was  as 
follows : — Mr.  Crosse  kneaded  some  pipeclay  into  the  consistency 
of  putty,  and  imbedded  in  it  a  piece  of  limestone  and  a  shell ;  this 
was  in  a  basin  :  he  then  made  a  mixture  of  powdered  sand  and  sul- 
phate of  iron  which  he  placed  above  the  pipeclay,  and  having  filled 
the  vessel  with  water  he  allowed  the  whole  to  stand  for  many  months. 
This  arrangement  was  made  in  imitation  of  a  natural  arrangement 
of  like  character  which  had  fallen  under  his  notice,  and  in  which  the 
shells  and  carbonate  of  lime  had  become  coated  with  sulphate  of 
lime.  In  hopes  of  attaining  the  same  result  artificially,  this  experi- 
ment was  instituted ;  and  to  the  great  satisfaction  of  the  author 
when  he  examined  the  results,  the  shell  and  the  limestone  had  lost 
in  weight,  and  around  each  were  crystals  of  sulphate  of  lime.  It  is 
Mr.  Crosse's  strong  conviction,  that  though  many  mineral  produc- 
tions may  result  from  the  direct  action  of  electric  currents,  yet  far 
the  largest  portion  proceed  from  operations  analogous  to  this, — 
from  the  direct  electrical  affinity  or  attraction  between  particles  of 
matter  coming  into  contact  by  this  slow  and  constant  action.  The 
only  point  in  which  this  experiment  differed  from  nature  is,  that 
the  vessel  in  which  the  operation  was  carried  on  was  not  porous.  On 
this  point  Mr.  Crosse  stated  a  fact  which  will  not  be  forgotten  by 
electrotypists,  that  voltaic  deposits  are  more  abundant  when  the 
vessel  employed  is  porous,  so  that  the  sulphate  of  copper  can  slowly 
filter  through.  A  series  of  experiments,  some  completed,  others  in 
progress,  were  then  described,  in  one  of  which  the  mould  of  a  sove- 
reign was  produced  in  solid  marble,  by  an  action  not  dissimilar  in 
principle  to  that  just  described ;  and  in  a  modification  of  the  ar- 
rangement a  rod  of  glass,  connected  with  the  positive  end  of  the 
battery,  was  gilded.  The  author  does  not  doubt  the  possibility  of 
forming  any  minerals,  even  the  precious  gems,  by  electric  agency. 
He  thinks  the  pearl  to  be  nothing  more  than  alternate  layers  of 
animal  and  mineral  substances,  electrically  concreted.  In  one  of 
the  experiments  a  magnificent  group  of  fine  Acari  were  developed  : 
the  production  of  these  insects  is  still  an  object  of  attention  to  Mr. 
Crosse,  and  he  anticipates  ere  long  communicating  with  the  Society 
on  the  subject. 

Mr.  Weekes's  Register  was  then  read :  and  the  Chairman  stated 
that  Mr.  Walker's  second  paper  on  Lightning  Conductors  would  be 
read  at  the  next  meeting.      

ROYAL  IRISH  ACADEMY. 
[Continued  from  vol.  xx.  p.  600.] 

May  10,  1841. — A  Note  on  some  new  Properties  of  Surfaces  of 
the  second  Order,  by  John  H.  Jellett,  Esq.,  F.T.C.D.,  was  read. 

I.  Let  the  points  on  the  focal  conic,  at  which  the  tangent  is  par- 
allel to  the  trace  of  the  tangent  plane,  be  considered  analogous  to  foci. 


Royal  Irish  Academy.  65 

II.  Let  the  axis  of  the  surface,  perpendicular  to  the  plane  of  the 
conic,  be  considered  analogous  to  the  conjugate  axis ;  then,  since 
the  square  of  the  distance  from  focus  to  centre,  in  a  conic,  is  equal 
to  the  difference  between  the  squares  of  the  transverse  and  conju- 
gate semi-axis,  we  may  consider,  as  analogous  to  the  transverse 
semi-axis,  the  line  drawn  to  the  extremity  of  the  perpendicular  axis 
from  the  point  analogous  to  the  focus. 

III.  Since  the  square  of  the  semiconjugate  diameter  is  equal  to 
the  sum  of  squares  of  semiaxes  minus  the  square  of  central  radius 
vector,  let  the  same  be  supposed  true  of  the  line  analogous ;  i.  e. 
if  A  be  the  line  analogous  to  the  transverse,  and  B  to  the  conjugate 
semi-axis,  let 

B'=  V  A2  +  B2  —  A'2. 
Assuming  these  definitions,  we  shall  have  the  following  theorems 
analogous  to  those  in  piano. 

1 .  The  sum  or  difference  (according  as  the  focal  conic  is  perpen- 
dicular to  a  real  or  imaginary  axis)  of  the  distances  from  the  points 
analogous  to  the  foci,  to  the  corresponding  point  on  the  surface,  is 
equal  to  2  A. 

2.  The  rectangle  under  them  =  B'2. 

3.  The  sine  of  the  angle,  made  by  either  with  the  tangent  plane, 
.    B 

13  W 

4.  The  rectangle  under  the  perpendiculars  from  these  points  on 
tangent  plane  =  B2. 

5.  The  sine  of  the  angle  between  the  central  radius  vector  and 

A  J\ 
tangent  plane  =  -^rs  (A'  beinS  the  central  radius  vector). 

6.  The  portion  of  the  normal  intercepted  between  the  surface 
and  the  plane  of  the  focal  conic  is  -jr  .  B'. 

7.  If  a  plane  be  drawn  perpendicular  to  the  line  joining  points 

A2 
analogous  to  the  foci,  and  at  a  distance  from  the  centre  equal  to  -p- 

(C  being  the  distance  of  one  of  the  focal  points  from  the  centre), 
the  distance  of  a  point  in  the  surface  from  the  corresponding  focus 
will  be  to  its  distance  from  this  plane  :  :  C  :  A. 

8.  Hence,  given  a  focal  conic  and  the  perpendicular  axis,  we  can 
find  points  and  tangent  planes  ad  libitum,  by  the  following  construc- 
tion:— Take  in  the  focal  conic  two  diametrically  opposite  points; 
with  one  as  centre,  and  twice  the  distance  from  it  to  the  extremity 
of  the  perpendicular  axis  as  radius,  describe  a  sphere.  Through  the 
other  point  draw  a  plane,  normal  to  the  focal  conic ;  it  will  cut  the 
sphere  in  a  certain  circle.  Connect  any  point  in  this  circle  with  the 
two  points  on  the  focal  conic,  and  at  the  middle  point  of  the  line 
connecting  it  with  the  second  point  draw  to  it  a  perpendicular  plane. 
This  is  a  tangent  plane  to  the  surface,  and  the  point  where  it  cuts 
the  first  connecting  line  is  a  point  on  the  surface. 

Another  mode  of  generating  the  surface  is  easily  derivable  from  (7 .). 
Phil.  Mag.  S.  3.  Vol.  2 1 .  No.  1 35.  July  1 842.         F 


66  Royal  Irish  Academy. 

TABLES  Nos.  I. 
Showing  the  Chemical  and  Physical  Properties  of  the  Atomic 


1. 

2. 

3. 

4. 

5. 

6. 

7. 

i 

2  . 

Chemical 

Composition  by 

Atomic 

Specific 

Frac- 

1 
1 

| 

1 

Constitution. 

weight  per  cent. 

weight. 

gravity. 

Colour. 

ture. 

i  — 

<  + 

»  + 

H  =  1 

'  1 

Cu  + 

100-00+         0 

31-6 

8-667 

Tile  red 

E. 

2 

10Cu  + 

Zn 

90-72+    9-28 

348-3 

8-605 

Reddish  yel.     1 

C.C. 

3 

9Cu  + 

Zn 

89-80+  10-20 

316-7 

8-607 

Reddish  yel.     2 

F.C. 

4 

8Cu  + 

Zn 

88-60+  11-40 

285-1 

8-633 

Reddish  yel.     3 

F.C. 

5 

7Cu  + 

Zn 

87-30+  12-70 

253-4 

8-587 

Reddish  yel.     4 

F.C. 

. 

6 

6Cu  + 

Zn 

85-40+  14-60 

221-9 

8-591 

Yellowish  red,  3 

F.F. 

c 

7 

5  Cu  + 

Zn 

83-02+  16-98 

190-3 

8-415 

Yellowish  red,  2 

F.C. 

N 

8 

4Cu  + 

Zn 

79-65+  20-35 

158-7 

8-448 

Yellowish  red,  1 

F.C. 

T3 

a 

9 

3Cu  + 

Zn 

74-58+  25-42 

1271 

8-397 

Pale  yellow 

F.C. 

1 

1(1 

2Cu  + 

Zn 

66-18+  33-82 

95-5 

8-299 

Full  yellow,      1 

F.C. 

01 

11 

Cu  + 

Zn 

49-47+  50-53 

63-9 

8-230 

Full  yellow,      2 

C.C. 

§■• 

12 

Cu  + 

2Zn 

32-85+  67-15 

96-2 

8-283 

Deep  yellow 

C.C. 

O 

i;s 

8  Cu  +  17  Zn 

31-52+  68-48 

801-9 

7-721 

Silver  white,      1 

C. 

1. 

14 

8Cu  + 

18  Zn 

30-30+  69-70 

834-2 

7-836 

Silver  white,     2 

V.C. 

i-i 

15 

8Cu  +  19  Zn 

29-17+  70-83 

866-5 

8-019 

Silver  grey,       3 

C. 

W 

i-i 

h; 

8Cu  + 

20  Zn 

28-12+  71-88 

898-8 

7-603 

Ash  grey,          3 

V. 

< 

17 

8  Cu  +  21  Zn 

27-10+  72-90 

931-1 

8-058 

Silver  grey,       2 

C. 

H 

18 

8Cu  + 

22  Zn 

26-24+  73-76 

963-4 

7-882 

Silver  grey,       1 

C. 

111 

8Cu  + 

23  Zn 

25-39+  74-61 

995-7 

7-443 

Ash  grey,          4 

F.C. 

20 

Cu  + 

3Zn 

24-50+  75-50 

128-5 

7-449 

Ash  grey,           1 

F.C. 

21 

Cu  + 

4Zn 

19-65+  80-35 

160-8 

7-371 

Ash  grey,          2 

F.C. 

22 

Cu  + 

5Zn 

16-36+  83-64 

1931 

6-605 

Very  dark  grey 

F.C. 

$a 

+ 

Zn 

0+100-00 

32-3 

6-895 

Bluish  grey 

T.C. 

r  i 

Cu  + 

Sn 

100-00+         0 

31-6 

8-667 

Tile  red 

E. 

2 

10Cu  + 

Sn 

84-29+  15-71 

374-9 

8-561 

Reddish  yel.      1 

F.C. 

Q 

3 

9Cu  + 

Sn 

82-81+  17-19 

343-3 

8-462 

Reddish  yel.     2 

F.C. 

H 

4 

8Cu  + 

Sn 

81-10+  18-90 

311-7 

8-459 

Yellowish  red,  2 

F.C. 

c 

g 

7Cu  + 

Sn 

78-97+  21-03 

280-1 

8-728 

Yellowish  red,  I 

V.C. 

« 

(5 

6Cu  + 

Sn 

76-29+  23-71 

248-5 

8-750 

Bluish  red,        1 

V. 

p. 

7 

5Cu  + 

Sn 

72-80+  27-20 

2169 

8-575 

Bluish  red,        2 

C. 

8 

4Cu  + 

Sn 

68-21+  31-79 

185-3 

8-400 

Ash  grey 

C. 

u* 

!) 

3Cu  + 

Sn 

61-69+  38-31 

153-7 

8-539 

Dark  grey 

T.C. 

1 

10 

2Cu  + 

Sn 

51-75+  48-25 

1221 

8-416 

Greyish  white,  1 

V.C. 

MH 

11 

Cu  + 

Sn 

34-92+  65-08 

90-5 

8-056 

Whiter  still,      2 

T.C. 

M 

12 

Cu-f- 

2Sn 

21-15+  78-85 

149-4 

7-387 

Whiter  still,      3 

C.C. 

J 
■ 

1,'! 

Cu-j- 

3Sn 

15-17+  84-83 

208-3 

7-447 

Whiter  still,      4 

C.C. 

£ 

14 

Cu  + 

4Sn 

11-82+  88-18 

267-2 

7-472 

Whiter  still,       5 

C.C. 

is 

Cu-}- 

5Sn 

9-68+  90-32 

3261 

7-442 

Whiter  still,      6 

E. 

[M 

+ 

Sn 

0+100-00 

58-9 

7-291 

White,               7 

F. 

Abbreviations  used  in  Column  7th  to  denote  character  of  fracture  :  —  F.C.  Fine 
Crystalline,  C.C.  Coarse  Crystalline,  T.C.  Tabular  Crystalline,  F.F.  Fine  Fi- 
brous, C.  Conchoidal,  V.C.  Vitreo-Conchoidal,  V.  Vitreous,  E.  Earthy. 

The  maxima  of  ductility,  malleability,  hardness,  and  fusibility,  are  =  1 . 

The  numbers  in  Column  6th  denote  intensity  of  shade  of  the  same  colour. 

The  atomic  weights  are  those  of  the  hydrogen  scale. 

The  specific  gravities  were  determined  by  the  method  indicated  in  Report  "  On 
Action  of  Air  and  Water  on  Iron,"  Trans.  Brit.  Assoc,  vol.  vii.  p.  283. 

The  ultimate  cohesion  was  determined  on  prisms  of  0-25  of  an  inch  square, 
without  having  been  hammered  or  compressed  after  being  cast.    The  weights 


Royal  Irish  Academy. 

AND  II. 

Alloys  of  Copper  and  Zinc,  and  of  Copper  and  Tin. 


67 


8. 

9. 

10. 

11. 

12. 

13.                                   14. 

c*  . 
.Sj= 

£ 

'H 

i 

1 

1J 

5 

-1 

■ 

3 

Relation  to 

VI  s 

Ir 

a 

.c  o 

1 
% 

Characteristic  properties,  in 
Working,  &c. 

cast  iron, in 
presence  of  a 
solvent,  i.  e. 

u 

V 

■a 

ft*  *-* 
hi  <a 
■a   .. 

1 

•0 

| 

•a 

sea- water. 

s  °* 

O 

o§ 

O 

O 

24-6 

8 

1 

22 

15 

Well  known. 

V     ■     J 

■3  1  1 

121 

6 

13 

21 

14 

1 

o  p  a* 

11-5 

4 

11 

20 

13 

Several  of  these  are 

w1    0.    . 

12-8 

2 

10 

19 

12 

Similar,  &c.    V    malleable  at  high 

S  O  2. 

13-2 

9 

9 

18 

11 

temperatures. 

..  *§  fd 

141 

5 

8 

17 

10 

J 

°  «  e 
1  g  * 

137 

11 

2 

16 

9 

Bath  metal. 

147 

7 

3 

15 

8 

Dutch  brass. 

131 

10 

4 

14 

7 

Rolled  sheet  brass. 

12-5 

3 

6 

13 

6 

British  brass. 

•  i  i  t 

9-2 

12 

5 

12 

6 

German  brass. 

%  ii  § 

^  w  W  w 

19-3 

1 

7 

10 

6 

brass,  watchmakers'. 

21 

0 

22 

5 

5 

Very  brittle," 

»ec 

2-2 

0 

23 

6 

5 

Very  brittle, 

Too  hard  to  file  or 

11 

07 

0 

21 

7 

5 

Very  brittle, 

turn,  lustre  nearly 

3  "2  ■ 

O    r    qj 

3-2 

0 

19 

3 

5 

Brittle, 

equal  to  speculum 

■ill 

0-9 

0 

18 

9 

5 

Brittle, 

metal. 

^o    .  . 

0-8 

0 

20 

8 

5 

Very  brittle,  j 

*s  c  1  a 

5-9 

0 

15 

1 

5 

Barely  malleable. 

■•111 

31 

0 

16 

2 

4 

Brittle. 

1-9 

0 

14 

4 

3 

White  button-metal. 

■*■*  o  «  >* 

1-8 

0 

17 

11 

2 

Brittle. 

-So      '3 

15-2 

13 

12 

23 

1 

Brittle,  well  known. 

■*«  ■£ .2  « 

24-6 

1 

2 

10 

16 

Well  known. 

"'gco 

161 

2 

6 

8 

15 

Gun-metal,  &c. 

1      ^ 

15-2 

3 

7 

5 

14 

Gun-metal,  &c. 

1  1    -  B 

177 

4 

10 

4 

13 

Gun-metal  and  bronze. 

.5  S  8* 

13-6 

5 

11 

3 

12 

Hard  mill  brasses,  &c. 

1  =  3 

3   S   <u 

9-7 
4-9 
07 
0-5 

0 
0 
0 

0 

12 
13 
14 
16 

2 
1 
6 
7 

11 

10 
9 

8 

Brittle, 
Brittle, 
Crumbles, 
Crumbles, 

All  these  alloys  found 
occasionally  in  bells, 
with  mixtures  of  Zn 
and  Pb. 

«3   1   g   g 

1      w            00 

W.S  2  S 

17 

0 

15 

9 

7 

Brittle, 

!«    o    «->    <u 

1-4 

0 

9 

11 

6 

Small  bells,  brittle. 

3-9 

0 

8 

12 

5 

brittle. 

o  ,E    „"* 

^  o  6  1 
M  S  o  s 

31 

0 

5 

13 

4 

Speculum  metal  of  authors. 

31 

8 

4 

14 

3 

files,  tough. 

1-    o          •-» 

2-5 

6 

3 

15 

2 

files,  soft  and  tough. 

tlli 

27 

7 

1 

16 

1 

Well  known. 

^  w-s  3  s 

given  are  those  which  each  prism  just  sustained  for  a  few  seconds  before  disrup- 
tion. 

The  copper  used  in  these  alloys  was  granulated,  and  of  the  finest  "tough  pitch;" 
the  zinc  was  Mossleman's,  from  Belgium  ;  and  the  tin  "  grain  tin,"  from  Corn- 
wall. They  were  alloyed  in  a  peculiar  apparatus,  to  avoid  loss  by  oxidation,  and 
the  resulting  alloy  verified  by  analysis. 

No  simple  binary  alloy  of  Cu  -f-  Zn  or  of  Cu  -j-  Sn  works  as  pleasantly  in 
turning,  planing,  or  filing,  as  if  combined  with  a  very  small  proportion  of  a  third 
fusible  metal,  generally  Cu  -f-  Zn  -f  Pb ;  or  Cu  -f-  Sn  -j-  Zn,  as  is  known  to 
workers  in  metals. 

F2 


68  Royal  Irish  Academy. 

May  24. — Mr.  Robert  Mallet  read  a  paper  "  On  the  Physical  Pro- 
perties and  Electro- Chemical  and  other  Relations  of  the  Alloys  of 
Copper  with  Tin  and  Zinc." 

These  experiments  are  collateral  to  the  researches  on  the  action 
of  air  and  water  on  iron,  upon  which  the  author  has  been  engaged 
at  the  desire  of  the  British  Association.  In  the  progress  of  these 
inquiries,  it  became  necessary  to  determine  the  action  of  solvents  on 
iron  in  presence  of  various  definite  alloys  of  copper  and  tin  and  of 
copper  and  zinc.  Hence  it  was  requisite  to  form  many  such  alloys 
in  rigidly  assigned  proportions  as  to  their  constituents,  a  matter 
known  to  experimenters  to  be  one  of  difficulty,  especially  in  the  case 
of  so  oxidable  and  volatile  a  metal  as  zinc.  The  difficulties  were 
overcome  by  a  peculiar  arrangement  of  apparatus,  permitting  the 
metals  to  be  fused  and  combined  in  close  vessels.  The  results  were 
verified  by  assay.  Having  these  alloys  which  belong  to  the  classes 
of  brass  or  gun-metal,  of  which  most  of  our  instruments  of  precision 
are  made,  and  their  constitution  being  atomic  and  certain,  it  seemed 
useful  to  determine  some  of  their  properties  for  practical  purposes. 
The  results  are  given  in  the  two  tables  prefixed,  pp.  66,  67. 

The  author  has  also  determined  the  numerical  conditions  govern- 
ing the  rate  of  solution,  or  amount  of  loss  sustained  in  a  given  time 
by  equal  surfaces  of  iron  in  solvent  menstrua,  when  in  presence  of 
all  these  alloys,  and  of  the  alloys  themselves.  Tables  of  these  were 
presented  :  the  results  do  not  seem  to  coincide  with  the  law  of  volta 
equivalents,  which  is  explained  by  showing  galvanometrically  that 
the  s  —  and  e  -f-  metals  of  the  alloy  are  often  not  acted  on  equally 
by  a  solvent;  thus,  that  an  alloy  of  Zny  +  Cu^  may  assume  a  cop- 
per surface  after  a  certain  time  of  reaction.  This  circumstance,  the 
author  has  shown,  suggests  a  method  of  determining  the  molecular 
arrangement  of  an  alloy ;  and,  in  general,  whether  any  alloy  be  a 
chemical  compound  or  a  mixture. 

The  author  also  enters  into  several  details  as  to  peculiar,  and,  in 
some  cases,  singular  reaction  of  these  and  other  alloys  upon  solutions 
of  the  salts  of  their  own  metals :  thus,  certain  alloys  of  lead  and 
zinc  decompose  solutions  of  lead  as  rapidly  as  pure  zinc ;  while 
others,  containing  much  zinc,  act  as  lead  towards  the  salts  of  lead. 

In  the  case  of  three  metals,  A,  B,  C,  whereof  A  is  s  + ,  and  C  is 
s  —  to  B,  the  author  investigates  the  question  as  to  what  will  be 
the  electro-chemical  relation  of  the  atomic  alloys  of  A^  +  Cy  to- 
wards B,  in  solvent  menstrua ;  and  in  the  class  of  alloys  of  copper 
and  zinc,  has  determined  the  alloy  of  no  action,  with  reference  to 
iron ;  and  has  also  found  alloys  which  protect  iron  in  solvents  elec- 
tro-chemically  as  fully  as  pure  zinc,  and  yet  are  not  themselves  acted 
on  by  the  solvent. 

He  enters  into  the  subject  of  the  specific  gravities  of  the  alloys  of 
Zn  +  Cu  and  Sn  -f  Cu  minutely,  and  shows  reason  to  doubt  the 
accuracy  of  the  published  specific  gravities  of  most  alloys  of  these 
and  some  other  classes. 


[  69  ] 

XIII.   Notices  respecting  New  Books. 

A  Cycle  of  Eighteen  Years  in  the  Seasons  of  Britain ;  deduced  from 
Meteorological  Observations  made  at  Ackworth  in  the  West  Riding 
of  Yorkshire,  from  1824  to  1841;  compared  with  others  before 
made  for  a  like  period  {ending  with  1823)  in  the  vicinity  of  London. 
By  Luke  Howard,  Esq.,  F.R.S.  With  Five  Plates.  London, 
Leeds,  and  Pontefract,  1842,  pp.  22,  8vo. 

WE  are  happy  to  find  from  the  little  work  now  before  us,  that  this 
veteran  meteorologist  is  still  prosecuting  his  labours  with  his 
pristine  ardour ;  and  we  congratulate  him  on  the  result,  now,  as  he 
truly  states,  ascertained  beyond  controversy,  that  a  periodical  revo- 
lution takes  place,  bringing  alternate  warmth  and  coldness  through 
successive  trains  of  seasons  in  our  variable  climate.  We  do  this 
with  the  greater  satisfaction,  because  we  think  that  between  the 
torrents  of  shameless  empiricism  on  the  subject  of  predicting  the 
changes  of  the  weather,  on  the  one  hand,  and  the  profound  and  ex- 
tensive systems  of  meteorological  observations  on  the  other,  which 
have  been  brought  forward  and  pursued  within  the  last  few  years, 
Mr.  Howard's  researches,  more  humble  perhaps  than  the  latter, — yet 
admirably  adapted  for  mathematical  investigation, — and  which  ought 
to  have  been  a  sufficient  antidote  to  the  former,  have  been  in  great 
measure  forgotten,  and  when  not  forgotten  still  not  duly  regarded. 

In  his  account  of  the  climate  of  London,  first  printed  1818-1820, 
and  reproduced  with  many  additions  and  improvements  in  1833,  Mr. 
Howard  gave  a  view  of  the  series  of  changes  embraced  by  the  cycle 
which  it  is  his  present  object  to  illustrate,  on  the  basis  which  his 
observations  then  seemed  to  present,  of  alternate  periods  of  seven 
and  ten  years,  the  former  ascending,  the  latter  descending  in  the  scale 
of  heat.  He  then  admitted,  from  appearances,  the  probability  of 
spaces  between  these  successive  periods  not  agreeing  with  this  rule, 
and  answering  to  the  "  intercalations "  of  an  imperfect  calendar. 
Having  since  pursued  the  subject  further,  he  finds  "  these  spaces  or 
interposed  years  to  be  necessary  parts  of  the  scheme  at  large,  which 
now  resolves  itself  into  a  cycle  of  eighteen  years,  in  which  our  sea- 
sons appear  to  pass  through  their  extreme  changes  in  respect  of 
warmth  and  cold,  of  wet  and  dryness." 

In  the  Proceedings  of  the  Royal  Society  for  March  1 1  and  April 
29,  1841  (or  Phil.  Mag.,  Third  Series,  vol.  xviii.  p.  552-559),  are 
given  abstracts  of  papers  containing  the  author's  views  on  this  sub- 
ject, as  regards  the  seasons  near  London,  then  read  before  the  So- 
ciety ;  and  one  of  those  papers,  relating  to  the  periodical  variations 
of  the  barometer  from  year  to  year  in  this  neighbourhood,  has  since 
been  published  in  the  Philosophical  Transactions*. 

*  In  the  paper  last  mentioned,  "  On  a  Cycle  of  Eighteen  Years  in  the 
Mean  Annual  Height  of  the  Barometer  in  the  Climate  of  London,  and  on 
a  constant  Variation  of  the  Barometrical  mean  according  to  the  Moon's 
Declination,"  the  author  showed  that  the  barometrical  mean  in  this  cli- 
mate is  depressed  (on  an  average  of  years)  by  the  moon's  position  in  south 


70  Notices  respecting  New  Books. 

Mr.  Howard's  present  object  is  to  bring  in  confirmation  of  the 
views  enunciated  in  his  former  work  and  in  the  papers  already 
alluded  to,  "  the  fact  of  a  new  period,  observed  \i  a  new  locality, 
and  that  differing  so  considerably  in  latitude  from  the  former,  as  to 
justify  the  inference  that  the  periods  are  not  confined  to  any  part 
of  our  island,  but  will  be  found,  variously  modified,  in  all." 

Referring  to  the  papers  above  mentioned,  Mr.  Howard  continues, 
"  For  a  variety  of  facts  relating  to  atmospheric  periodicity,  stated  in 
a  more  elaborate  way,  I  shall  here  briefly  analyse  the  results  of  the 
Ackworth  Register,  and  apply  them  to  my  object;  saying  little 
about  the  barometer,  however,  because  the  present  observations  on 
this  instrument,  however  constantly  made  from  day  to  day,  have  not 
the  comprehensive  character  of  those  insisted  on  in  my  former  pa- 
pers ;  which  were  taken  from  the  face  of  a  registering  clock.  The 
Tables  annexed  to  this  paper,  then,  comprise  the  results  of  a  daily 
meteorological  Register,  kept  at  my  instance,  and  with  instruments 
furnished  by  myself,  at  the  Friends'  Public  School  in  Ackworth.  I 
have  observations,  not  so  continuous,  made  at  my  own  residen.ce 
there ;  by  collation  with  which  in  many  parts  I  have  satisfied  myself 
that  I  can  depend  on  these,  for  the  purpose  to  which  they  are  here 
applied,  of  deducing  the  differences  of  seasons  from  previous  and 
subsequent  ones  of  like  denomination,  by  comparison  with  each 
other." 

We  cannot  follow  the  author  through  the  particulars  which  con- 
stitute his  memoir,  nor  describe  in  detail  the  plates,  all  consisting 
of  curves  or  flexuous  lines  traced  on  rectangular  scales,  exhibiting 
the  range  of  the  temperature,  depth  of  rain,  &c.  for  the  eighteen 
years  composing  the  cycle.  The  following  extract,  explanatory  of 
one  of  them,  will  serve  to  indicate  their  nature  : — 

"  The  dotted  curve,  or  flexuous  line  in  tig.  1.  shows  the  variation  from 
year  to  year  of  the  mean  temperature,  or  average  heat  of  the  year,  the  mean 

declination  ;  and  that  there  is  also  manifested  in  the  lunar  influence  a  gra- 
dation of  effects  which  operates  through  a  cycle  of  eighteen  years. 

Mr.  Howard's  researches  on  this  subject  had  been  commenced  prior  to 
the  first  publication  of  his  Climate  of  London,  at  the  suggestion  of  Silvanus 
Bevan,  Jun.,  and  had  been  further  discussed  in  the  second  edition  of  that 
work,  published  in  1833  :  their  results,  as  given  in  the  paper  now  referred 
to,  recalled  the  attention  of  Sir  John  W.  Lubbock  to  a  paper  by  himself 
in  the  Companion  to  the  British  Almanack  for  1839,  in  which  he  had  in- 
serted certain  results  obtained  with  a  view  of  ascertaining  the  influence  of 
the  moon  on  the  barometer  and  on  the  dew-point,  some  of  which  appeared 
to  indicate  that  the  moon's  position  in  declination  influences  the  baro- 
meter. Investigating  the  subject  in  a  manner  altogether  different  from 
that  adopted  by  Mr.  Howard,  but  capable  of  more  rigorous  application, 
his  results,  as  stated  in  a  paper  of  which  an  abstract  is  given  in  the  Pro- 
ceedings of  the  Royal  Society  for  March  25,  1841  (or  Phil.  Mag.,  Third 
Series,  vol.  xviii.p.  555),  seem  to  indicate  an  elevation  of  nearly  one-tenth 
of  an  inch  for  17  degrees  of  declination. 

We  have  noticed  Sir  John  W.  Lubbock's  discussion  of  the  subject  sim- 
ply in  relation  to  the  history  of  this  point  in  meteorological  science;  it  has 
no  direct  or  particular  bearing  on  the  contents  of  the  work  before  us. 


Howard's  Cycle  of  Eighteen  Years  in  the  Seasons  of  Britain.  71 

of  ike  climate  (or  average  of  all  the  observations  of  these  eighteen  years) 
being  48°*126*.  The  nine  years  from  1824  to  1832  average  48°*879;  the 
nine  years  from  1833  to  1841  give  470,374.  The  difference  of  1-405  is 
about  equal  to  the  difference  in  warmth  between  Ackworth,  N.  lat.  53° 
38'  57",  and  London.  I  therefore  call  the  former  nine  the  warm,  and  the 
latter  nine  the  cold  years  of  the  cycle.  The  curve  shows  palpably  the 
bulk  of  the  years  of  high  temperature  on  the  right,  and  of  those  of  low 
temperature  on  the  left  of  the  dividing  line,  but  with  two  striking  excep- 
tions. There  is  a  very  cold  year,  1829,  among  the  warm,  and  a  very  warm 
year,  1834,  among  the  cold;  and  these  considerably  reduce  the  difference 
between  the  two  averages  :  the  comparison  or  contrast  holds  best,  there- 
fore, among  the  years  in  detail. 

"  The  full  flexuous  line  in  fig.  1.  shows  the  variation  from  year  to  year 
of  the  total  rain  collected  by  the  gauge  in  each.  It  is  not  here  as  with  the 
temperatures  ;  the  amount  of  rain  is  balanced,  or  nearly  so,  in  each  nine 
years.  Thus  out  of  472-93  inches  fallen  in  the  whole  cycle,  238-60  inches 
appear to  have  fallen  on  the  warm,an&  234-33  inches  on  the  cold  side,  making 
the  ann-ual  averages  respectively  26*51  and  26*04  inches  nearly  ;  which  is 
about  an  inch  more  on  the  whole  per  annum  than  is  found  to  fall  near  Lon- 
don— the  level  being  at  the  ground,  in  both.  If  we  .now  look  through  the 
curve  (I  beg  pardon  of  mathematicians  for  applying  the  term  to  such  a  line), 
we  shall  probably  be  first  struck  with  an  extreme  of  dryness  (1826)  fol- 
lowed by  an  extreme  of  wetness  (1828)  on  the  warm  side;  then,  with  a 
gradation  from  very  wet  (again  following  very  dry)  in  1830  to  very  dry  in 
1835 ;  and  this  again  mounting  by  steps  to  extreme  wet  again  in  1839.  In 
fact,  ten  years,  from  1830  to  1839,  show  a  gradual  decrease,  and  again  an 
increase  of  rain,  protracted  through  the  half-cycle,  while  eight  years,  from 
1840  to  1829  (passing  thus  back  to  make  the  cycle),  show  repeated  and 
more  extended  oscillations  performed  in  shorter  times ;  yet  with  results 
so  nearly  the  same,  that  the  first  set  of  years  here  specified  show  an  average 
rain  of  26*36  inches,  while  the  second  set  average  26*16  inches.  Again,  on 
comparing  rain  with  temperature,  we  find  1826  in  the  extreme  at  once  of 
xvarmth  and  dryness,  and  1839  in  those  of  wet  and  coldness ;  but  1828  (in 
the  extreme  of  wetness)  is  equal  in  heat  to  the  dry  1826;  and  1829  is  both 
dry  and  very  cold.  The  quantity  of  rain  therefore  is  not  regulated  by  the 
temperature  of  the  year :  we  may  get  it  with  heat,  brought  by  winds  highly 
vaporized  from  the  tropic ;  or  with  cold,  from  the  condensation  effected 
by  the  approach  of  northern  air  to  our  own  atmosphere,  previously  charged 
with  vapour  to  the  full ;  and  the  dryness  of  1829,  with  so  much  of  cold, 
may  have  been  the  result  of  the  great  deposition  of  rain  in  the  previous 
season.  The  only  rule  then  that  prevails  throughout  seems  to  be  compen- 
sation ;  a  wet  year  against  a  dry  one,  &c,  and  so  of  whole  runs  of  seasons ; 
and  we  must  examine  the  winds  for  the  cause." 

The  author  next  proceeds,  from  the  review  of  the  rain  and  tem- 
perature of  whole  years,  as  above,  to  an  analysis  of  the  distribution 
of  these  through  the  several  months  of  the  year,  with  the  view  of 
ascertaining  the  "  difference,  under  equal  quantities  of  rain,  of  the 
warm  from  the  cold  side  of  the  cycle,  as  regards  the  most  important 
of  its  effects,  the  fruitful  or  unfruitful  character  of  our  seasons." 

A  full  flexuous  line  in  fig.  2..  presents  the  monthly  rain,  in  its 
total  amounts  under  each  month,  for  the  nine  years  1824  to  1832, 

*  The  numbers  are  here  stated  as  given  in  the  Corrigenda  at  the  end  of 
the  work. 


72  Notices  respecting  New  Books. 

or  warm  period  ;  a  dotted  curve,  the  same  for  the  nine  years  1833 
to  1841,  or  cold  period  of  the  cycle. 

Fig.  3.  gives  the  rain  under  each  month,  for  the  whole  eighteen 
years,  represented  by  a  full  line  ;  in  connexion  with  the  average 
temperature  of  each  month  for  the  like  series  of  years,  in  a  curve 
corresponding  as  nearly  as  those  in  the  author's  Climate  of  Lon- 
don, with  the  curve  of  the  sun's  declination,  which  is  placed  in  a 
fine  dotted  line,  in  connexion  with  both. 

In  figures  4,  5,  6,  and  7  are  given  the  rain  and  temperature  of 
the  four  seasons  of  the  year,  through  the  cycle  here  treated. 

The  results  in  figures  from  which  these  lines  and  curves  are  laid 
down,  are  all  given  in  tables,  either  introduced  into  or  annexed  to 
the  work. 

The  mean  height  of  the  barometer  for  the  warm  period  of  the 
cycle,  taken  at  Ackworth  School,  is  29*851  inches:  that  for  the 
cold  period  29*807  :  the  mean  of  the  entire  cycle  is  29*829 ;  the 
warm  side  having  the  higher  average  of  pressure  by  0*44  inch. 

The  mean  temperature  we  have  already  noticed. 

The  rain  of  the  warm  years  amounts  to  238*60  inches ;  of  the 
cold  to  234*33  ;  rain  of  the  whole  cycle  472*93,  or  per  annum 
26  27  inches;  the  warm  side  averaging  26*51  inches,  the  cold 
26*037  ;  but  the  author  has  "found  cause,  on  examining  into  past 
periods,  to  conclude  that  the  small  excess  of  rain  here  found  on  the 
warm  side  is  not  a  constant  result ;  but  that  the  cold  may  sometimes 
be  the  wetter."  The  main  point  affecting  our  harvests  appears  to  be 
the  different  distribution  of  the  rain  within  the  year  in  each  period, 
which  he  next  proceeds  to  examine. 

After  concluding  the  discussion  of  the  observations,  Mr.  Howard 
remarks, — 

"  It  is  proper  I  should  caution  my  reader  against  expecting  too  much 
from  the  information  here  presented  to  him.  Should  he  look  for  the  same 
mean  temperature  and  the  same  amount  of  rain  in  each  returning  year  of  the 
coming  cycle,  as  are  found  recorded  of  a  corresponding  one  in  the  past,  he 
will  probably  meet  with  frequent  disappointments ;  and  this  more  espe- 
cially in  a  locality  somewhat  different.  We  are  yet  far  from  being  able  to 
predict  seasons  in  meteorology  with  the  like  certainty  of  date  as  the  astro- 
nomer does  the  coming  phamomena  of  the  heavens;  and  it  is  even  possible 
that,  from  the  very  nature  of  the  causes  concerned,  we  may  never  arrive 
at  this.  The  judicious  observer,  finding  certain  facts  fully  ascertained  and 
clearly  noted  for  him,  ivill  know  how  to  make  use  of  these  for  himself;  and 
by  watching  their  occurrence  in  detail,  making  notes  as  he  proceeds,  will 
endeavour  to  feel  his  own  way  towards  the  future,  independently  of  empi- 
rical and  fallacious  predictions.  This  is  the  kind  of  service  which  I  expect 
my  present  labour  to  render  to  the  country;  besides  gratifying  a  reasonable 
curiosity  as  to  the  past.  We  do  not  expect  to  become  skilful  in  other  arts 
without  a  due  share  of  study  and  practice ;  but  we  seem  to  forget  this  self- 
evident  truth  when  we  take  up  that  of  foretelling  the  weather.  The  facts 
here  detailed  cannot  fail  to  be  useful  to  such  as  will  be  at  the  trouble  to 
examine  and  compare  them,  though  the  inferences  they  may  draw  from 
them  should  differ.  And  admitting  only  that  in  the  course  of  years  here 
treated,  we  experience  in  succession  the  various  degrees  of  warmth  and 
coldness,  of  rain  and  dryness,  incident  to  our  climate,  it  must  needs  help 


Intelligence  and  Miscellaneous  Articles.  73 

the  farmer,  the  market-gardener,  the  planter  or  nurseryman,  the  grazier, 
the  sheep-master,  to  have  before  him  such  an  approximation  to  the  times 
and  order  of  their  occurrence. 

•  •**»** 

"  There  is  a  class  of  persons,  however,  to  whom  the  paper  may  be  imme- 
diately acceptable,  and  possibly  also  useful  in  regulating  their  future  plans. 
The  poor  invalid  may  be  soothed,  and  those  of  delicate  constitutions  en- 
couraged, by  the  immediate  prospect  of  a  nine  years'  run  of  seasons  having, 
with  little  exception,  the  higher  temperature  of  our  climate.  It  may  be  the 
means  of  inducing  these  to  make  trial  at  least  of  one  or  two  of  these,  before 
they  resort  to  other  skies  more  favoured  by  natural  position,  but  extending 
over  countries  far  less  desirable  as  residences  to  a  truly  British  mind.  And 
medical  gentlemen,  when  they  have  read  and  considered  what  is  here  laid 
before  them,  may  find  arguments  in  it  to  strengthen  such  a  conclusion." 

The  work  terminates  with  tables,  showing  the  mean  height  of  the 
barometer,  mean  temperature,  and  depth  of  rain  in  each  month,  at 
Ackworth,  Yorkshire,  through  the  cycle  of  eighteen  years  from 
1824  to  1841. 


XIV.   Intelligence  and  Miscellaneous  Articles. 

ON  THE  RED  MOLYBDATE  OF  LEAD.      BY  M.  G.  ROSE. 

IT  is  well  known  that  the  molybdate  of  lead  from  Retzbanya  in  the 
Bannat  is  distinguished  by  its  red  colour  from  the  other  varieties, 
and  particularly  from  that  which  is  found  at  Bleyberg  in  Carinthia ; 
the  crystallization  of  these  two  varieties  is,  however,  the  same.  Prof. 
Johnston  lately  made  some  researches  to  discover  chromic  acid  in  the 
red  crystals ;  he  submitted  them  to  examination  by  the  blow-pipe 
and  reported  that  they  were  entirely  chromate  of  lead ;  and  he  con- 
cluded from  this  that  chromate  of  lead  is  a  dimorphous  body. 

I  brought  with  me  from  Siberia  some  red  crystals  of  molybdate  oi 
lead,  perfectly  similar  to  those  of  Retzbanya,  and  I  was  able,  not- 
withstanding their  extreme  smallness,  on  account  of  the  great  bright- 
ness of  their  faces,  to  measure  the  angles  with  the  reflective  gonio- 
meter :  their  form  is  the  haupto-octohedron  of  molybdate  of  lead, 
slightly  truncated  on  the  superior  edges.  The  inclination  of  the 
faces,  which  by  their  intersection  form  their  superior  edges, is  99°  38', 
and  that  of  the  lateral  faces  is  131°  55'.  I  also  submitted  these 
small  crystals  to  the  action  of  the  blow-pipe,  and  obtained  results 
different  from  those  stated  by  Prof.  Johnston.  I  was  hence  induced 
to  examine  the  crystals  of  Retzbanya,  and  I  found  that  they  behaved 
with  every  test  like  the  molybdate  of  lead  of  Bleyberg  (Berzelius, 
Trait6  du  Chalumena,  3e  edition,  §  252).  There  is  only  one  exception 
to  this  general  statement :  when  fused  with  an  excess  of  borax  in  the 
exterior  flame  the  red  crystals  yield  a  glass  which  becomes  opake 
on  cooling,  and  has  a  slightly  greenish  colour,  whilst  the  glass  ob- 
tained from  the  Bleyberg  crystals  is  of  a  very  pure  white. 

The  crystals  of  Retzbanya  are  easily  decomposed  in  a  mixture  of 
hydrochloric  acid  and  alcohol ;  a  crystalline  precipitate  of  chloride  of 
lead  is  formed,  and  the  solution,  which  is  greenish  and  transparent, 


74  Intelligence  and  Miscellaneous  Articles. 


"t3 


yields  by  evaporation  a  blue  mass  of  oxide  of  molybdenum,  similar  to 
that  obtained  by  the  same  means  from  the  yellow  lead  of  Bleyberg. 
When  tried  by  the  blow-pipe  no  difference  is  found  between  the  two 
oxides. 

It  results  from  the  preceding  researches,  that  far  from  being 
composed  entirely  of  chromic  acid  and  oxide  of  lead,  as  Professor 
Johnston  has  stated,  the  red  variety  of  yellow  lead  consists  princi- 
pally of  molybdate  of  lead ;  it  may  however  contain  a  little  chromic 
acid.  The  presence  of  this  acid  is  readily  explained  by  the  ana- 
logous composition  of  chromic  and  molybdic  acids. — Annates  des 
Mines,  tome  xvii. 

[Note. — In  our  last  Number  the  measure  of  the  angles  of  leu- 
cophan  was  stated  as  given  in  the  Journal  ftir  praktische  Chemie ; 
the  reader  will  perceive  that  there  must  be  some  error  in  the  state- 
ment, but  which  we  have  not  the  means  of  correcting.  With  respect 
to  andesine,  also,  we  followed  the  same  authority  in  mentioning  it 
to  have  been  found  "  in  twin  crystals  very  similar  to  albite,"  yet  it 
is  stated  to  be  a  leucite  :  this  is  not  very  intelligible  when  we  re- 
collect that  albite  has  a  doubly  oblique  prism,  and  leucite  a  cube,  as 
their  primary  forms. — Ed.] 

METHOD  OF    DISTINGUISHING   BETWEEN    WEAK    SOLUTIONS  OF 
NITRATES  AND  CHLORATES.       BY  M.  VOGEL,  JUN. 

When  a  few  drops  of  tincture  of  litmus  are  added  to  a  solution  of 
nitrate  of  potash  so  as  to  render  it  blue,  and  afterwards  concentrated 
sulphuric  acid,  the  tincture  is  merely  reddened  by  the  sulphuric  acid, 
and  by  the  nitric  acid  set  free,  but  it  is  not  at  all  decolorated.  A 
solution  of  chlorate  of  potash,  on  the  contrary,  which  has  been  ren- 
dered blue  by  tincture  of  litmus,  is  entirely  decolorated  by  the 
addition  of  concentrated  sulphuric  acid,  a  result  by  which  the  chlo- 
rate is  effectually  distinguished  from  the  nitrate. 

This  effect  is  produced  with  the  chlorate  when  one  part  is  dis- 
solved in  sixty-four  parts  of  water,  but  it  ceases  with  eighty  parts  of 
water ;  but  a  solution  of  indigo  is  decolorated  when  water  contains 
only  one-500th  of  its  weight  of  chlorate  of  potash. 

This  method  of  distinguishing  the  chlorates  from  the  nitrates, 
both  in  very  dilute  solutions,  has  besides  the  advantage  of  giving 
certain  results,  in  decolorating  the  tincture  of  litmus,  even  when  the 
chlorates  are  accompanied  with  chlorides  and  other  salts. 

Tincture  of  litmus  is  not  decolorated  by  a  very  weak  solution  of 
nitrate  of  potash  on  the  addition  of  sulphuric  acid,  even  when  some 
hundredths  of  common  salt  or  of  other  chlorides  are  present :  it  is 
decolorated  only  when  the  nitrate  of  potash  is  dissolved  in  a  con- 
centrated solution  of  common  salt. — Journ.  de  Pharm.  et  de  Chim., 
Mai  1842.  

ON  THE  EXISTENCE  OF  SULPHUR  IN  PLANTS. 
M.  Vogel,  Sen.,  remarks,  that  it  has  been  proved  by  the  late  M. 
Planche  and  other  chemists,  that  many  plants  contain  sulphur.    Wa- 


Intelligence  and  Miscellaneous  Articles.  75 

ter-cresses,  Lepidium  sativum,  L„  are  among  those  which  especially 
contain  much  sulphur. 

As  soils  distant  from  volcanos  do  not  contain  perceptible  traces  of 
sulphur,  it  appears  to  M.  Vogel  not  impossible  that  plants,  which 
are  much  disposed  to  assimilate  sulphur,  may  have  the  property  of 
deriving  it  from  the  decomposition  of  the  sulphuric  acid  of  sulphates. 
M.  Vogel,  however,  found  that  seeds  placed  in  a  soil  perfectly  free 
from  sulphur  and  sulphates,  yielded  plants  which  contained  a  notable 
quantity  of  sulphur. 

The  soil  employed  for  this  experiment  consisted  of  coarsely  pow- 
dered white  glass ;  it  was  first  strongly  heated,  but  not  fused,  in  a 
crucible,  and  being  afterwards  washed  with  boiling  water,  not  the 
slightest  trace  of  any  sulphate  could  be  detected. 

Seeds  of  water-cresses  kept  in  a  moist  state  were  placed  in  this, 
and  when  the  plants  were  several  inches  in  height,  they  were  re- 
moved with  their  roots  ;  after  having  washed  the  plants,  the  white 
fibrous  roots  were  cut  off,  and  these  as  well  as  the  plants  were  dried, 
and  on  heating  them  in  a  retort,  it  was  found  that  both  of  them 
yielded  considerably  more  sulphur  than  the  seeds  contained;  the 
expressed  juice  of  the  young  plants  cultivated  in  the  powdered  glass 
also  contained  soluble  sulphates.  The  seeds  of  water- cresses,  sown 
in  coarsely  powdered  quartz,  flint-glass,  and  very  fine  silica  obtained 
from  silicated  hydrofluoric  acid,  yielded  similar  results  with  respect  to 
sulphur  and  sulphates,  though  the  plants  did  not  flourish  so  well  in 
the  last  as  in  the  two  former  substances. 

To  obtain  approximative  results  as  to  the  quantity  of  sulphur  in 
the  water-cress  seeds  and  the  plants  which  they  yielded,  the  follow- 
ing experiments  were  made  : — The  seed  [100  grains  ?]  was  heated  to 
redness  in  a  retort,  and  the  gases  disengaged  were  received  into  a 
solution  of  potash;  acetate  of  lead  was  added  to  the  alkaline  liquor  as 
long  as  precipitation  occurred.  The  precipitate  was  of  a  brownish 
colour,  and  consisted  of  hydrate,  carbonate  and  sulphuret  of  lead ;  the 
two  former  were  dissolved  by  dilute  nitric  acid,  and  the  sulphuret  of 
lead  remained,  which  after  washing  and  drying  weighed  0'95  gr., 
which  indicated  0*129  gr.  of  sulphur.  According  to  this  experiment, 
100  grs.  of  the  seed  contained  0'129  gr.  of  sulphur. 

The  young  plants  obtained  from  the  growth  of  100  grains  of  the 
seed  were  similarly  treated  ;  their  weight  was  2040  grs.;  they  yielded 
by  the  above- described  processes  15"  1  grs.  of  sulphuret  of  lead,  equi- 
valent to  2"03  grs.  of  sulphur :  consequently  the  dried  plants  con- 
tained nearly  fifteen  times  as  much  sulphur  as  the  100  grs.  of  seed 
which  produced  them. 

Another  experiment  was  made  by  projecting  into  a  red-hot  pla- 
tina  crucible  small  successive  portions  of  a  mixture  of  powdered 
cress-leaves  with  nitrate  and  carbonate  of  potash.  The  residue, 
heated  in  the  crucible  and  treated  with  nitric  acid,  gave  a  con- 
siderable precipitate  with  chloride  of  barium,  but,  on  account  of  the 
sulphate  of  potash  which  the  plant  contains,  the  quantity  of  sul- 
phur cannot  be  accurately  determined  by  this  process,  although  in 
general  it  is  preferable  to  that  above  described ;  100  grs.  of  the 


76  Intelligence  and  Miscellaneous  Articles. 

leaves  yielded  in  this  way  4*6  grs.  of  sulphate  of  barytes,  equiva- 
lent to  0*624  gr.  of  sulphur;  but  the  quantity  of  sulphate  of  potash 
is  to  be  deducted  from  this. 

As  the  growth  of  the  young  plants  of  water-cresses  took  place  in 
a  soil  devoid  of  sulphur  and  sulphates,  and  in  a  room  which  con- 
tained no  sulphurous  vapours,  the  origin  of  the  sulphur,  M.  Vogel 
remarks,  is  to  him  a  perfect  enigma,  and  at  present  he  confesses  that 
he  is  unable  to  give  a  satisfactory  explanation  of  it. — Journ.  de  Pharm. 
et  de  Chim.,  Mai  1842. 


ACTION  OF  SALTS  ON  LIVING  PLANTS. 

From  the  various  experiments  which  M.  Vogel,  Sen.  has  made 
on  the  action  of  salts  on  living  plants,  he  has  arrived  at  the  following 
conclusions : — 

1st.  That  plants  with  their  roots  when  immersed  into  a  solution 
of  sulphate  of  copper,  totally  absorb  the  salt,  convert  it  into  proto- 
sulphate,  and  die  quickly. 

2nd.  That  acetate  of  copper  produces  the  same  effects,  the  salt 
absorbed  becoming  proto-acetate  of  copper. 

3rd.  That  plants  absorb  sulphate  of  magnesia,  nitrate  of  potash, 
and  iodide  of  potassium,  and  die  more  or  less  quickly. 

4th.  That  the  sulphates  of  zinc  and  manganese  are  absorbed  by 
plants  without  suffering  decomposition,  and  the  plants  die. 

5th.  That  plants  absorb  nitrate  of  cobalt  and  nickel,  without 
being  able  to  absorb  the  whole  of  them  from  solution ;  but  they  die, 
and  the  same  effect  is  produced  by  emetic  tartar. 

6th.  That  the  oxalate  and  tartrate  of  oxide  of  chromium  and 
potash  are  slowly  absorbed  by  plants,  and  the  bichromate  of  potash 
much  more  quickly.  The  Datura  Stramonium  and  Galega  officinalis 
absorb  the  salt  of  chromium  with  the  greatest  rapidity ;  they  become 
of  a  yellow  colour  and  die. 

7  th.  That  plants  absorb  nitrate  of  silver ;  but  they  decompose  it, 
and  the  oxide  of  silver  is  reduced  to  the  metallic  state. 

8th.  That  plants  absorb  also,  and  totally,  the  protonitrate  of  mer- 
cury from  solution,  but  the  salt  is  decomposed. 

9th.  That  corrosive  sublimate  is  absorbed  by  plants;  some  of  them 
decompose  it  into  calomel,  and  others  absorb  it  without  decomposi- 
tion. 

10th.  That  plants  slowly  absorb  acetate  of  lead ;  and  it  is  de- 
composed by  some  plants  and  not  by  others. 

11th.  That  plants  which  contain  much  carbonate  of  lime,  such  as 
the  Chara  vulgaris  and  the  Stratiotes  alo'ides,  do  not  absorb  a  salt  of 
copper  from  solution :  the  same  also  occurs  with  the  Cereus  vari- 
abilis.— Ibid. 


ON  CHLORITE  AND  REPIDOLITE.      BY  M.  KOBELL. 
Chlorite  is  characterized  by  the  proportion  of  water  which  it  con- 
tains, and  by  its  property  of  being  completely  decomposed  by  sul- 
phuric acid.    M.  Kobell  made  a  comparative  analysis  of  four  varie- 


Intelligence  and  Miscellaneous  Articles.  77 

ties  from  Schwarzenstein  in  Zillerthal,  from  Achmatof  in  Siberia,  from 
Grenier  in  Zillerthal,  and  from  Roures  near  Salzbourg.  They  were 
treated  with  sulphuric  acid  in  a  platina  crucible  ;  the  excess  of  acid 
was  expelled  and  the  residue  treated  with  hydrochloric  acid;  the 
iron  and  alumina  were  precipitated  with  carbonate  of  barytes,  and 
the  alkalies  were  sought  for  but  not  found. 
The  results  were — 

Schwarzenstein.  Achmatof. 

Silica 32-68       31-14 

Alumina 14-57 17*14 

Magnesia    33-11       3440 

Protoxide  of  iron    597       03-85 

■■      manganese       0-28       0'53 

Water     12-10       12*20 

Gangue 1'02       Q-85 

99-73  100-11 

Zillerthal.  Roures. 

Silica 27-32       26-96 

Alumina 20*89       18-47 

Magnesia   24*69       14-69 

Protoxide  of  iron 15'23       26-87 

manganese       0*47       0-62 

Water 12-00       1045 

100-60       Gangue.  1*24 

99-30 
The  composition  of  the  first  two  chlorites  differs  essentially  from 
that  of  the  two  latter;  and  M.  Kobell  considers  that  the  first  two 
form  a  new  species,  to  which  he  gives  the  name  of  repidolite  (pierre 
en  eventail). 

The  repidolite  of  Schwarzenstein  is  of  an  emerald-green  colour  by 
transmitted  light,  and  crystallizes  in  hexagonal  tables  with  trian- 
gular aggregated  laminae  ;  it  is  accompanied  with  amianthus. 

The  repidolite  of  Achmatof  is  of  an  emerald-green  colour  parallel 
to  one  of  its  axes,  and  of  an  asparagus-green  perpendicular  to  it ; 
its  crystallization  is  hexagonal,  and  it  is  associated  with  garnet. 

The  chlorite  of  Zillerthal  is  penetrated  with  crystals  of  magnetic 
iron,  and  becomes  black  before  the  blow-pipe  ;  that  of  Roures  also 
becomes  black  when  heated  by  the  blow-pipe,  and  is  more  fusible 
than  that  of  Zillerthal. — Annales  des  Mines,  tome  xvii. 


ANALYSIS  OF  THE  TACHYLYTE  OF  VOGELSGEBIRGE. 
BY  M.  KLETT. 

Ten  years  ago  the  late  Professor  Humdeshagen  gave  the  analysis 
of  a  mineral  under  the  name  of  tachylyte  of  Vogelsgebirge,  which 
was  perfectly  similar  to  that  of  Sasebuhl ;  of  this  there  is  no  ana- 
lysis, and  we  have  that  only  of  the  mineral  from  Vogelsgebirge  ;  this 
mineral  has  a  specific  gravity  of  2*7144;  before  the  blow-pipe  it 
fuses  into  an  opake  glass  free  from  bubbles ;  fragments  of  consi- 
derable size  fuse  into  a  globule  on  charcoal ;  with  microscomic  salt 


78  Intelligence  and  Miscellaneous  Articles. 

it  fuses  into  a  transparent  pearly  bead,  which  becomes  opake  on 
cooling.  On  heating  this  glass  in  the  reducing  flame,  the  reaction 
indicating  titanic  acid  (a  red  colour)  is  not  perceptible ;  most  fre- 
quently it  is  of  a  pale  violet  colour,  like  titanic  acid  with  borax. 
Tachylyte  in  powder  fuses  into  a  greenish  bead,  which  is  without 
bubbles,  and  is  transparent  even  after  cooling ;  strong  hydrochloric 
acid  acts  upon  it,  even  when  cold,  and  separates  gelatinous  silica ; 
and  in  analysing  it  the  action  of  this  acid  was  continued  till  the 
titanic  acid  was  dissolved  by  avoiding  the  degree  of  heat  which 
would  have  rendered  it  insoluble. 
The  results  of  the  analysis  were— 

Silica 50*220 

Titanic  acid 1*415 

Alumina 17*839 

Lime    8*247 

Soda    5-185 

Potash 3-866 

Magnesia 3-374 

Protoxide  of  iron 10-266 

manganese       0*397 

Ammoniacal  water  ....        0*497 

101-306 
The  tachylyte  does  not  contain  titanic  acid  in  the  state  of  tita- 
niate  of  iron,  for  this  is  not  acted  upon  by  cold  hydrochloric  acid ; 
the  calcined  mineral  is  also  acted  upon  by  this  acid,  but  the  silica  is 
of  a  brown  colour. — Annates  des  Mines,  tome  xvii. 


ANALYSIS  OF  NATIVE  ALUMI NATES. 

M.  II.  Rose  states  that  native  aluminates  which  are  decomposed 
with  so  much  difficulty  and  so  imperfectly  by  the  .alkaline  carbonates, 
and  even  by  hydrate  of  potash,  which  also  resist  the  action  of  hy- 
drofluoric acid>  and  in  the  analysis  of  which  Abich  has  so  success- 
fully employed  carbonate  of  barytes,  are  completely  and  readily  de- 
composed by  fusion  with  bisulphate  of  potash. 

He  first  employed  it  in  the  analysis  of  the  chlorospinelle  of  Fla- 
tonsk  :  this  mineral  was  reduced  to  fine  powder  in  a  steel  mortar 
without  having  been  previously  bruised  in  an  agate,  flint  or  chalce- 
dony mortar,  was  heated  with  bisulphate  in  a  platina  crucible  over  a 
spirit-lamp  with  a  double  current  of  air,  until  the  powder  was  com- 
pletely dissolved. 

The  fused  mass  dissolved  entirely  in  water,  and  the  constituent 
principles  of  the  solution  may  be  determined  by  the  well-known 
methods.  The  alumina,  when  the  quantity  is  not  too  small,  ought 
to  be  redissolved  in  hydrochloric  acid,  and  precipitated  by  carbonate 
of  ammonia,  to  avoid  an  excess  of  it  in  the  result.  The  use  of  the 
bisulphate  of  potash  especially  requires  this  precaution,  because  the 
salts  of  the  fixed  alkalies  are  separable  with  so  great  difficulty  from 
precipitated  alumina  by  washing. 

M.  Rose  did  not  find  any  silica  in  the  chlorospinelle,  although 


Meteorological  Observations.  79 

this  mineral  occurs  in  schistose  talc,  and  consequently  in  a  silicate. 
A  series  of  experiments  proved  that  silica  is  entirely  wanting  in  na- 
tive aluminates,  such  as  the  corundum  of  China  and  Bengal,  Oriental 
sapphire,  the  spinel  of  Ceylon  and  Norway,  the  gahnite  of  Ekeberg  ; 
and  that  the  silica  found  by  other  chemists  comes  from  the  agate 
mortar  in  which  the  mineral  is  pulverized. 

Though  the  bisulphate  of  potash  is  very  advantageously  employed 
in  the  analysis  of  aluminates,  it  is  not  applicable  to  that  of  those  si- 
licates which  are  not  decomposable  by  acids.  Felspar  is  only  par- 
tially decomposable  by  this  salt :  it  is  therefore  evident  that  silica  is 
a  much  stronger  acid  than  alumina  when  it  acts  the  part  of  an  acid ; 
for  if  the  bisulphate  of  potash  so  readily  effects  the  decomposition  of 
aluminates,  it  is  entirely  because  alumina  always  acts  as  a  base  with 
sulphuric  acid. — Ann.  der  Chem.und Pharm.,  and  Journ.  dePharm.  et 
de  Chim.,  Mai  1842. 


SOCIETE  GEOLOGIQUE  DE  FRANCE. 

We  are  able  to  inform  our  readers,  that  the  great  Annual  Meeting 
of  the  French  Geologists  will  take  place  this  year  on  Sept.  4th,  at 
Aix  (dept.  Bouches  du  Rh6ne),  and  we  have  no  doubt  will  be  at- 
tended by  a  vast  number  of  foreigners,  attracted  both  by  the  beauty 
and  geological  interest  of  the  neighbourhood. 


METEOROLOGICAL  OBSERVATIONS  FOR  MAY  1842. 

Chiswick. — May  1,2.  Clear  and  very  dry.  3,4.  Very  fine.  5.  Cloudy:  heavy 
rain.  6.  Fine:  showery.  7.  Rain:  stormy  showers.  8.  Cloudy:  stormy. 
10,  11.  Very  fine.  12.  Drizzly.  13 — 15.  Slight  haze  in  the  mornings:  very 
fine  :  clear  at  night.  16,  17.  Very  fine:  clear.  18,  19.  Overcast.  20.  Densely 
clouded.  21.  Cloudy  and  fine.  22.  Cloudy  and  fine:  slight  rain.  23.  Cloudy. 
24.  Rain.  25.  Rain  :  overcast.  26.  Rain  :  cloudy :  clear  at  night.  27.  Cloudy 
and  fine.     28.  Very  fine.     29,30.  Clear  and  very  fine.     31.  Very  fine  :  cloudy. 

Boston. — May  1,  2.  Fine.  3.  Cloudy.  4.  Fine.  5,6.  Fine  :  rain  p.m.  7. 
Cloudy:  rain  a.m.  and  p.m.  8.  Windy.  9 — 11.  Fine.  12.  Rain.  13.  Fine. 
14.  Foggy.      15,  16.  Fine.      17— -19.  Cloudy.      20.  Rain.      21,  22.  Cloudy. 

23.  Fine.      24.  Rain  :  rainy  day.      25.  Cloudy.      26.  Rain :  rain  early  a.m. 
27.  Cloudy.     28.  Fine:  rain  early  a.m.     29.  Fine.    30.  Cloudy.     31.  Fine. 

Sandwick  Manse,  Orkney. — May  1 .  Clear :  fog.  2.  Cloudy :  clear.  3.  Clear  : 
cloudy.  4.  Cloudy  :  damp.  5.  Cloudy:  rain.  6.  Bright:  cloudy.  7.  Cloudy  : 
thunder.  8.  Showery.  9.  Cloudy.  10.  Rain:  clear.  11,  12.  Cloudy.  IS- 
IS. Clear.  16.  Clear:  fog.  17.  Fog  cloudy.  18.  Cloudy.  19.  Cloudy: 
drizzle.  20.  Cloudy:  shower.  21.  Bright:  shower.  22.  Clear.  23.  Clear: 
fog.  24.  Clear:  cloudy.  25.  Cloudy:  damp.  26.  Bright:  cloudy.  27. 
Bright :  shower.  28.  Bright :  cloudy.  29.  Cloudy  :  showery.  30.  Bright : 
cloudy.     31.  Bright. 

■dpplegarth  Manse,  Dumfries-shire. — May  1,2.  Dry  and  withering.  3.  Cloudy. 
4.  Fine.  5.  Cloudy,  with  rain.  6.  Showery.  7.  Wet  day.  8.  Showers  a.m.  : 
cleared.  9.  Fair,  but  cool.  10.  Fair,  but  threatening.  11.  Showery.  12 — 17. 
Fair  and  fine.  18.  Fair  and  fine,  but  cloudy.  19.  Fine  rain  p.m.  20.  Rain 
and  hail.     21.  Fair  and  fine.      22.  Showery.      23.  Showery:  growing  weather. 

24.  Showery.      25.  Fair  and  fine.       26.  One  shower  :  fine  p.m.      27.  Fair  and 
fine.     28.  Fair  till  noon  :  then  rain.     29,30.  Showers.     31.  Slight  showers. 

Sun  shone  out  29  days.      Rain  fell  12  days.     Thunder  2  days.     Hail  1  day. 

Wind  North-east  1  day.  East  3  days.  East- south-east  1  day.  South-east  5 
days.  South-south-east  4§  days.  South  5  days.  South-west  4$  days.  West- 
south-west  4  days.     West  1£  day.     North-west  1£  day. 

Calm  7  days.  Moderate  14  days.  Brisk  2  days.  Strong  breeze  6  days. 
Boisterous  2  days. 


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THE 
LONDON,  EDINBURGH  and  DUBLIN 

PHILOSOPHICAL  MAGAZINE 

AND 

JOURNAL  OF  SCIENCE. 


[THIRD  SERIES.] 


AUGUST  1842. 


XV.  On  the  Scientific  Labours  o/*Jeremias  Benjamin  Richter. 
Addressed  to  the  Imperial  Academy  of  Sciences  of  St.  Peters- 
burg, at  the  public  sitting  of  Dec.  29,  1840,  by  M.  Hess, 
Member  of  the  Academy*. 

Gentlemen, 

THERE  is  perhaps  no  one  here  present  who  does  not 
reckon  amongst  the  fairest  enjoyments  of  thought  those 
moments  which  from  time  to  time  he  is  able  to  devote  to  the 
remembrance  of  men  of  genius  who  have  bequeathed  to  us 
important  truths.  And  when  I  proceed  to  show  that  the  veil 
which  obscures  the  memory  of  one  of  these  has  yet  to  be 
torn  away, — that  the  labours  of  twenty  years  employed  in  ren- 
dering a  truth  evident  to  the  eyes  of  the  most  incredulous,  are 
not  yet  appreciated, — you  will  then,  I  cannot  doubt,  grant  me 
a  moment  of  the  attention  which  your  kindness  would  not 
have  refused  to  a  cause  less  disinterested. 

In  the  exact  sciences,  as  in  all  other  cases,  nature  does  not 
allow  us  to  proceed  per  saltum ;  it  is  necessary  that  every  thing 
should  be  unfolded  gradually.  It  is  the  most  simple  phaeno- 
menon  which  first  takes  its  place  in  the  domain  of  intelligence  ; 
the  most  complicated — themostdifficull,  is  that  which  comesthe 
last.  Thus  when  at  the  beginning  of  the  eighteenth  century, 
astronomy,  thanks  to  the  numerous  labours  summed  up  by  the 
mind  of  one  great  man,  thanks  to  the  simplicity  of  his  prin- 
ciple, assume'd  the  rank  of  a  science  almost  perfect,  about  that 
time  did  chemistry,  with  difficulty,  attempt  to  assume  a  sci- 
entific form.  You  will  perhaps  suppose  that  this  is  to  be  at- 
tributed to  the  men  who  were  engaged  in  it;  but  you  will 
soon  abandon  this  idea  when  I  tell  you  that  Newton,  who  dis- 
covered the  law  of  gravitation,  also  applied  himself  to  che- 
mistry, that  he  decomposed  the  subtile  matter  of  light,  whilst 

*  From  the  Recueil  des  Actes  de  la  Seance  Publique,  Dec.  29, 1 840. 

Phil.  Mag,  S.  3.  Vol.  21.  No.  136.  Aug.  1 842.         G 


82  M.  Hess  on  the  Scientific  Labours  of  Richter. 

not  only  the  air,  but  water  and  even  earth  still  resisted  the 
efforts  of  three  generations. 

However,  George  Stahl,  a  resident  at  Berlin,  established 
his  theory  of  phlogiston  which  so  long  preserved  its  dominion 
in  the  mind.     Air  was  at  last  decomposed,  and  water  also. 
Lavoisier  next  analysed  the  phaenomenon  of  combustion  ;  and 
from  this  period  the  new  ideas   became  diffused;   the   im- 
pulse was  given,  earth  itself  was  analysed,  and  the  number  of 
combinations  was  increased  in  a  wonderful  manner,  without  the 
existence  as  yet  of  any  known  law  to  reduce  this  labyrinth  to 
order.     Many  persons  still  remember  the  manner  in  which 
analyses  were  recorded ;  everythingwas  reduced  to  hundredths, 
and  thence  resulted  a  confusion  the  shackles  of  which  must 
have  been  felt,  in  order  to  appreciate  the  system  of  notation 
now  used,  at  its  just  worth.   It  was  Jeremias  Benjamin  Richter, 
assessor  at   the  office  of  mines    at  Berlin,  who    first  gave 
order  to  this  chaos.     You  therefore  would  expect  that  the 
highest  esteem  would  invest  his  works,  that  his  name  was 
revered.     No;  Richter  was  not  appreciated,  he  was  almost 
forgotten  whilst  alive.     He  died  at  Berlin  the  4th  of  May, 
1807.    The  same  year  a  celebrated  author  tells  us,  that  being 
employed  in  drawing  up  a  treatise  on  chemistry,  amongst 
other  works  but  little  read  he  ran  through  those  of  Richter. 
He  was  struck  with  the  mass  of  light  which  he  found  there ; 
but  by  a  fatal  chance  he  attributed  to  Wenzel,  whose  works 
he  must  have  read  at  the  same  time,  the  most  beautiful  result 
obtained  by  Richter,  that  which  was  to  serve  for  a  foundation 
to  the  whole  edifice.     In  order  to  explain  how  it  was  that 
Richter  had  been  forgotten,  the  author  to  whom  we  allude 
says  that  his  results  were  not  exact,  which  must  have  weak- 
ened the  impression  the  perusal  of  his  works  must  have  made, 
and  so  much  the  more  as  Richter  almost  always  took  the  carbo- 
nate of  alumina  as  the  point  of  departure,  a  combination  which 
we  know  does  not  exist.     Let  us  not  be  surprised,  then,  that 
the  most  celebrated  French  authors  repeat,  on  the  authority 
of  a  great  name,  the  same  errors  concerning  works  which  they 
have  not  read ;  we  see,  for  example,  the  author  of  the  Leqons 
sur  la  Philosophic  Chimique  explain  things  in  the  same  way, 
and  reduce  the  merit  of  Richter  almost  to  nothing.  "  Can  you 
believe,"  says  he,  '*  that  in  establishing  his  doctrines  he  nearly 
always  takes  the  carbonate  of  alumina  as  the  point  of  depart- 
ure ?"     In  short,  Richter  is  there  reproached  with  having  too 
much  obscured  the  questions  upon  which  Wenzel  had  begun  to 
throw  light  *. 

[*  Our  own  countryman  Dr.  Wollaston,  it  would  appear,  justly  appre- 
ciated the  labours  of  Richter :  see  the  paper  explaining  his  "Synoptic  Scale 
of  Chemical  Equivalents"  in  the  Philosophical  Transactions  for  1814,  p.  3, 4. 
—Edit.] 


M.  Hess  on  the  Scientific  Labours  of  Richter.        83 

If  in  general,  gentlemen,  it  is  a  duty  to  render  justice  to 
merit,  in  the  present  case  it  is  at  the  same  time  a  right;  for 
J.  B.  Richter,  almost  unknown  by  the  rest  of  Europe,  was 
elected  a  correspondent  of  this  Academy  on  the  1 4th  of  May 
1800.  Let  us  examine  his  title  to  our  esteem.  It  is  the  best 
homage  we  can  render  to  his  memory. 

Richter  published  in  1792  and  1793,  a  work  in  three  vo- 
lumes under  the  title  of  Anfangsgrunde  der  Stochiometrie, 
oder  Messkunst  chemischer  Elemente,  in  which  he  sets  forth 
his  ideas  in  the  form  of  a  systematic  treatise.  But  this  form, 
you  know,  is  little  suited  for  spreading  new  ideas.  How  can 
a  reader  be  expected  to  gather  five  hundred  known  ideas  in 
order  to  discover  one  that  is  original !  Has  not  each  professor 
his  treatise,  and  would  it  not  be  a  punishment  to  have  to  study 
nearly  the  greater  part  of  it?  This  mode  of  publication  does 
not  promise  success  to  any  but  authors  who  have  already  ac- 
quired great  celebrity,  and  with  whose  works  we  are  obliged  to 
become  acquainted.  So  Richter,  beginning  by  a  work  in  three 
volumes,  was  not  read.  Seeing  that  the  great  truth  which  he  had 
in  view  was  not  appi'eciated,  that  he  was  exposed  to  unjust  cri- 
ticisms, whilst  his  work  was  not  read,  he  resolved  to  publish 
his  researches  separately,  which  he  did  under  this  title,  Ueber 
die  neueren  Gegenstdnde  der  Chemie,  in  eleven  small  volumes 
of  from  100  to  250  pages  each.  They  appeared  from  1793 
until  1802.  "I  should  (says  Richter  in  1799)  certainly  not 
have  followed  up  these  two  first  volumes  (Stiicke)  by  seven 
others,  if  too  severe  a  criticism  of  the  antiphlogistic  school 
did  not  endeavour  to  put  under  the  bann  of  sound  reason  all 
those  who  think  differently  from  it,  and  if  to  this  was  not  added 
the  annoying  circumstance  that  my  Stochiometrie,  although 
endowed  with  a  sound  constitution,  is  nevertheless  consigned 
to  the  shelf  of  the  shop-keeper." 

In  the  introduction  to  the  first  part,  Richter  tells  us  he 
hopes  that  the  part  of  chemistry  which  treats  of  affinities  and 
quantities  will  soon  become  a  part  of  applied  mathematics. 
Here  then  is  the  preconceived  idea,  the  point  whence  Richter 
set  out; — weigh  even  the  form  of  his  expressions,  and  you 
divine  nearly  all  his  life.  "  Some  experiments  which  I  have 
just  made,  having  the  same  aim  in  view  (says  Richter,  vol.  i. 
§  121),  make  me  think  that  if  we  could  employ  suitable 
expedients,  we  should  find  that  the  neutrality  of  pure  ele- 
ments, setting  out  from  one  amongst  them  which  is  taken  as 
unit,  increases  in  a  positive  progression."  We  see  the  idea 
was  truly  philosophical ;  it  was  necessary  to  develop  it  and  to 
become  assured  whether  such  a  relation  existed  or  not.  It 
was  a  source  of  serious  errors  to  him,  and  drew  upon  him  too 
severe  judgements.  He  devoted  a  part  of  his  works  to  fathom 

G2 


84-  M.  Hess  on  the  Scientific  Labours  of  Richter. 

this  question,  and  remained  persuaded  that  the  equivalent  of 
all  bases  belongs  to  an  arithmetical  progression,  whilst  the 
numbers,  which  express  the  equivalents  of  the  acids,  form 
geometrical  progressions,  the  ratio  of  which  is  different  ac- 
cording to  the  different  groups  of  acids. 

Now  it  is  well  established  that  facts  do  not  support  this  no- 
tion of  Richter's:  we  shall  therefore  pass  over  this  part  of 
his  works,  and  I  shall  return  to  them  but  once,  in  order  to 
show  how  it  was  that  his  experiments  were  sometimes  so 
far  from  the  truth  as  not  to  undeceive  him.  But  if  we  go 
back  to  the  time  when  he  lived,  we  shall  feel  that  the  question 
raised  was  vast,  and  that  if  his  undertaking  was  not  crowned 
with  success,  he  at  least  deserves  that  these  words  should  be 
applied  to  him: 

"  Quern  si  non  tenuit,  magnis  tamen  excidit  ausis." 

Amongst  the  numerous  subjects  which  Richter  treats  of  in 
the  first  volume,  I  shall  only  quote  the  method  which  he  points 
outforextractingplatinum  from  the  ore  of  that  metal ;  foritis  still 
used.  He  recommends  precipitating  the  solution  of  that  metal 
by  sulphate  of  potash,  to  wash  and  dry  the  precipitate  and  to 
decompose  it  by  the  carbonate  of  potash,  so  as  to  divest  it 
afterwards  of  all  the  salts  by  washing  it  with  water.  The 
metal  then  remains  brilliant  as  silver.  The  explanation  of 
the  processes  follows,  which  gives  him  an  opportunity  of 
making  some  very  important  remarks.  When  we  shall  have 
found,  says  he,  numerical  expressions  for  affinity,  then  these 
seeming  anomalies  will  disappear.  Upon  this  occasion  he 
explains  the  difference  between  simple  affinity  and  double  af- 
finity, and  observes  that  it  is  nowhere  proved  that  we  can 
really  isolate  a  simple  body,  for,  he  says,  each  time  that  we 
disengage  an  alkali  or  a  metallic  acid,  if  it  be  only  carbonic 
acid,  heat  must  then  be  substituted  for  the  acid ;  lime  is  an 
example  of  this.  So  it  is  with  the  acid  from  which  we  take  a 
base,  it  is  combined  with,  or  even  neutralized  by  heat.  In 
the  case  of  a  simple  affinity,  we  suppose  but  two  elements, 
whilst  this  shows  you  that  there  are  at  least  three,  for  every 
time  that  neutrality  takes  place,  heat  is  substituted  for  the 
third  element.  This  is  even  the  case  when  a  metal  is  dissolved  by 
an  acid  and  neutralizes  it,  for  then  it  is  the  acid  that  furnishes 
the  heat,  which  becomes  united  with  the  other  elements. 
Richter  therefore  knew  that  bodies  were  pervaded  by  heat; 
he  urges  the  necessity  of  taking  these  phaenomena  into  con- 
sideration, but  he  does  not  yet  take  a  perfectly  just  view 
of  them;  he  believes  that  heat  is  just  added  to  the  elements, 
when  we  know,  on  the  contrary,  that  it  has  just  been  disen- 
gaged. 


M.  Hess  on  the  Scientific  Labours  o^  Richter.         85 

The  third  volume  (1793)  is  wholly  devoted  to  a  critical  ex- 
amination of  Lavoisier's  antiphlogistic  system.  Up  to  that 
time  Richter  had  only  known  it  by  very  insufficient  extracts. 
But  in  1792  appeared  a  German  translation  of  Lavoisier's 
treatise  on  chemistry,  by  Girtanner.  Richter  obtained  and 
read  it,  and  was  convinced  of  the  truths  of  the  new  system. 
Yet  indulgent  towards  others  and  a  stranger  to  the  spirit  of 
party,  he  excuses  those  who  refuse  to  admit  it.  "  For,"  he 
says,  "  in  the  ancient  system,  metals  and  sulphurs  were  con- 
sidered as  compound  bodies,  earths  and  acids  as  simple  bodies; 
in  the  new  system  it  is  just  the  contrary :  now  imagine  a  man 
whom  you  would  persuade  that  all  he  sees  he  sees  reversed, 
and  then  condemn  him  for  his  incredulity.  But,  neverthe- 
less, an  error  does  not  become  a  truth  should  it  even  count 
myriads  of  ancestors." 

Do  not  suppose  however  that  Richter,  upon  embracing  the 
new  system  openly,  abandons  himself  to  it  without  criticism. 
No.  No  one  to  my  knowledge  has  better  perceived  what  there 
was  good  in  the  fundamental  principle  of  the  phlogistic  system. 
We  must  not  expect  that  a  system  which  served,  for  nearly 
a  century,  as  a  starting-point  for  the  numerous  investigations 
of  chemists,  that  a  system  which  could  rally  round  it  all 
facts,  should  be  entirely  illusive.  "  All  the  facts  on  which 
the  partisans  of  the  antiphlogistic  system  rest,"  says  Richter, 
"  are  not  only  insufficient  for  the  refutation  of  the  reality  of 
phlogiston;  but  on  the  contrary,  they  do  but  rectify  our 
ideas  with  regard  to  it  and  render  its  existence  more  evi- 
dent ;  for  example,  when  we  assert  that  phosphoric  acid  is 
composed  of  phosphorus  and  oxygen,  this  conclusion  has  no 
foundation,  since  in  reality  no  other  conclusion  can  be  drawn 
from  the  experiment,  except  that  this  acid  is  composed  of  the 
radical  of  phosphorus  and  of  oxygen.  Not  any  induction  can 
be  drawn  respecting  the  nature  of  this  radical  itself,  for  it  is  only 
known  as  combined  with  oxygen  or  with  phlogiston  (Brenn- 
stoff). ;  which,  however,  does  not  prevent  us  from  indicating 
the  relative  quantity  of  the  elements,  since,  for  us,  the  weight  of 
phlogiston,  like  that  of  heat,  is  an  infinitely  small  quantity." 
Such  was  the  capacity  of  Richter's  mind,  that  in  the  midst  of  the 
lively  contention  of  two  parties  who  do  not  agree,  he  quietly 
examines  the  question,  seizes  the  literally  palpable  truths  of 
the  new  school,  and  yet  does  not  abandon  the  more  abstract, 
more  hidden  but  not  less  real  truths  of  the  old  system.  Per- 
haps Richter  had  a  model,  but  then  this  model  was  Lavoisier, 
and  no  other.  But  it  is  certain  that  at  the  present  time,  this 
manner  of  viewing  the  subject  is  banished  from  all  works  which 
treat  of  this  science,  and  that  it  is  after  a  lapse  of  forty  years 


86  M.  Hess  on  the  Scientific  Labours  of  Richter. 

that  considerations  of  another  order,  supported  by  decisive 
experiments,  seem  to  enable  us  to  appreciate  his  ideas  pro- 
perly. 

Before  Richter,  and  in  his  time  also,  it  was  supposed  that 
the  affinity  of  a  substance  was  in  the  direct  ratio  of  the  quan- 
tity necessary  to  saturate  another  body.  Richter  compares 
the  quantities  of  tartaric  and  of  acetic  acid  necessary  to  satu- 
rate the  same  quantity  of  lime.  He  finds  that  more  tartaric 
acid  is  necessary,  and  concludes  that  its  affinity  is  greater, 
and  that  consequently  this  acid  should  displace  acetic  acid. 
He  makes  trial  of  this,  and  really  it  is  tartaric  acid  which 
seizes  the  lime  and  displaces  the  acetic  acid.  Few  examples 
are  found  more  suitable  than  this  for  characterizing  the  dif- 
ficulties which  are  met  with  every  day  in  chemistry,  for  here 
is  a  well-observed  fact,  a  conclusion  drawn ;  an  hypothesis 
follows,  then  comes  the  experiment  which  confirms  it.  You 
believe  your  principle  well  established  ?  By  no  means.  An- 
other fact  comes  and  overturns  it.  Subsequently  Richter 
again  takes  up  the  question,  and  this  time  he  clearly  proves, 
that  affinity  is  not  exerted  in  the  ratio  of  the  masses  which  com- 
bine.— Vol.  x.  p.  187-195. 

It  is  in  the  fourth  volume  (viertes Stuck,  1795)  that  Richter 
establishes  truths  which  will  always  be  reckoned  amongst  the 
most  important  acquisitions  in  the  region  of  the  exact  sci- 
ences. He  begins  by  researches  on  the  capacity  of  saturation 
of  hydrofluoric  acid;  for  this  he  uses  several  bases,  and  does 
not  neglect  alumina.  He  tells  us  (p.  10)  that  he  took  650 
grains  of  very  pure  carbonate  of  alumina,  which  he  saturated 
with  hydrofluoric  acid.  Here  then  is  what  he  is  accused  of, 
for  carbonate  of  alumina  does  not  exist !  The  parenthesis,  then, 
where  he  says  that  1000  parts  of  this  alumina  contained  542 
of  pure  alumina,  has  not  been  read.  Nor  have  his  calculations 
been  followed,  for  he  everywhere  takes  into  account  alumina 
at  the  rate  of  542  parts  for  1000.  All  of  you,  gentlemen,  who 
addexperience  to  a  general  knowledge  of  chemistry,  will  know 
that  it  is  very  difficult,  I  may  say  almost  impossible,  to  obtain 
pure  alumina ;  if  we  precipitate  it  from  its  solutions  by  the  car- 
bonate of  ammonia,  it  always  retains  a  little  of  this  salt,  and 
water  besides.  It  is  only  by  calcination  that  we  can  obtain  it 
really  pure ;  but  then  it  becomes  difficult  to  dissolve  in  acids. 
This,  doubtless,  is  the  reason  why  Richter  used  non-calcined 
alumina,  and  determined  by  a  separate  experiment  the  real 
amount  of  that  earth  which  it  contained. 

After  having  found  the  quantity  of  different  bases  by  which 
1000  parts  of  hydrofluoric  acid  were  saturated,  a  verifi- 
cation is  required.    For  this  purpose  he  decomposes  fluoride 


M.  Hess  on  the  Scientific  Labours  of  Richter.  87 

of  calcium  by  sulphuric  acid,  and  infers  the  quantity  of  lime 
to  be  found  in  the  hydrofluate  from  the  quantity  contained  in 
the  sulphate.  He  thus  finds  by  analysis,  that  1000  parts  of 
hydrofluoric  acid  require  1882  of  lime  for  their  saturation ; 
by  synthesis  he  finds  1865  parts.  After  that,  he  finds  that 
the  same  quantity  of  acid  was  saturated  by  3797  parts  of 
potash,  and  continues  in  these  terms :  "  It  has  been  shown 
(he  speaks  of  his  Stochiometrie)  that  the  quantities,  whether 
of  alkali,  or  of  alkaline  earth,  which  served  to  saturate  the 
same  quantity  of  one  of  the  three  volatile*  mineral  acids, 
were  in  constant  relation  with  each  other."  Richter  then  ex- 
amines whether  the  results  which  he  has  just  obtained  sup- 
port this  proof:  he  had  before  found  that  1000  parts  of  mu- 
riatic acid  require  1107  parts  of  lime  for  perfect  saturation, 
and  2239  of  potash.  For  hydrofluoric  acid  he  had  obtained 
1882  parts  and  3797.  But  1107  :  2239  sfe  188.2  :  3807,  which 
differs  very  little  from  the  result  of  the  experiment. 

A  happy  and  important  discovery  is  not  all;  the  consequences 
of  it  must  be  felt;  the  promptitude  of  intelligence  must  go 
beyond  the  tardiness  of  experience,  for  it  is  only  in  this  future 
that  we  can  be  armed  against  all  the  shackles  of  the  present. 
Now  this  is  the  manner  in  which  Richter  announces  and 
extends  the  consequences  of  his  experiments  (vol.  iv.  p.  67, 
year  1795).  When  two  determining  {determinants)  elements 
(i.  e.  two  acids,)  each  taken  at  the  rate  of  1000  parts,  are  satu- 
rated by  the  substances  a,  b,  c,  d  and  a,  |S,  7, 8,  so  that  each 
time  a  and  a,  b  and  /3,  &c.  are  always  the  same  substance ; 
in  this  case  the  (substances)  quantities  a,  bf  c  are  among  them- 
selves absolutely  in  the  same  relation  as  «.,  /3,  y. 

This  theorem  of  Richter's  is  a  true  touchstone  for  all  ex- 
periments which  relate  to  neutrality ;  for  if  the  results  do 
not  agree  with  this  principle,  they  must  be  rejected  without 
hesitation.  But,  he  adds,  although  according  to  the  announce- 
ment of  the  principle  we  may  use  relations  known  and  deter- 
mined by  experiment,  in  order  to  find  others  by  calculation, 
it  will  always  be  useful  to  verify  these  last  by  the  fact,  for  we 
gain  by  it,  after  having  recognised  certain  relations,  the  means 
of  verifying  the  numbers  themselves  from  which  we  had  set 
out,  and  thus  to  correct  the  little  inaccuracies  by  which  they 
might  be  affected. 

Richter  then  points  out  the  work  to  be  done ;  but  in  order  to 
feel  all  the  importance  there  is  in  its  being  done  with  the  greatest 
precision,  it  will  suffice  to  tell  you  that  he  forms  a  plexus  of 
number,  which  covers  the  entire  domain  of  chemical  researches 
whatever  they  may  be,  and  that  it  is  precisely  from  not  having 

*  By  these  he  understood  the  sulphuric,  nitric  and  muriatic  acids. 


88  M.  Hess  on  the  Scientific  Labours  of  Richter. 

performed  analysis  with  skill  enough,  that  Richter  remained 
all  his  life  uncertain  on  several  points. 

Here  is  certainly  one  of  the  most  striking  proofs  of  the  pro- 
gress we  owe  to  him.  He  makes  analyses,  and  deduces  a  general 
principle  from  them,  and  from  that  time  these  same  analyses 
are  no  longer  sufficient  for  the  increasing  wants  of  the  science. 
To  set  out  from  hence  the  task  imposed  by  Richter  becomes 
gigantic.  New  methods  are  necessary.  We  owe  them  to  M. 
Berzelius ;  it  is  he  who  executed  this  work  with  a  precision 
very  rarely  equalled,  and  which  not  only  has  not  been  sur- 
passed, but  never  will  be  by  these  methods. 

Richter,  after  having  established  this  principle,  continues  to 
apply  himself  to  the  subject;  he  determines  the  capacity  of 
saturation  of  acetic  acid,  by  lime,  by  magnesia,  by  barytes, 
and  finds  that  in  order  to  saturate  1000  parts  of  this  acid,  sup- 
posed anhydrous,  Ca  523,  Mg  405*6,  Ba  1465  are  necessary, 
which  gives  for  the  composition  of  these  salts, 

According  to  Richter.  According  to  Berzelius. 

For  100  of  Ca  A  . .  Ca  34-34.  A  65*66  Ca  35-63  A  64*37 
MgA..Mg28*8  71'2  Mg28*66  71*34. 
Ba  A  . .  Ba  59*  4      40*  6      Ba  59*  8       40*  2 

Let  us  observe  that  there  is  no  question  of  alumina ;  it  is, 
says  he,  because  he  is  not  able  to  find  with  precision  the  point 
of  saturation  for  this  base.  You  therefore  see  a  real  difficulty 
which  stops  him,  this  combination  being  one  of  those  which 
he  is  more  certain  of  determining  by  calculation  than  by  ex- 
periment. 

These  researches  lead  Richter  to  the  conclusion  that  acetic 
acid  follows  the  same  law  as  the  acids  before  considered.  He 
then  shows  that  the  same  law  is  also  applicable  to  the  citric, 
oxalic,  tartaric,  formic,  and  several  other  acids.  It  is  essential 
to  observe,  that  in  order  thus  to  prove  by  experiment  the  ge- 
nerality of  the  principle  which  he  had  established,  an  entire 
series  of  analyses  was  necessary  for  each  acid,  and  it  will  be 
easy  to  judge  of  the  ardour  and  time  he  must  have  expended 
on  these  labours.  But  in  these  same  works  he  applies  his 
principle ;  as  for  example,  he  often  meets  with  difficulties  in 
finding  the  point  of  saturation  for  carbonic  acid,  he  sets  out 
then  from  a  combination  which  he  thinks  well  known.  There 
again  he  avoids  alumina  as  not  adapted  to  his  object,  and  he 
selects  carbonate  of  lime.  His  choice  could  not  then  fall  better. 
He  finds  that  1000  parts  of  carbonic  acid  are  saturated  by 

1373  parts  of  lime,  which  gives  for  100  parts  Ca  57*86  and 


M.  Hess  on  the  Scientific  Labours  o/*  Richter.  89 

C  42'14 ;  according  to  Berzelius,  Ca  56*29 +  C  43-71.  Not 
only  does  Richter  not  choose  the  carbonate  of  alumina,  but 
he  examines  the  question  to  discover  why  the  carbonate  of  this 
base  treated  by  an  acid  disengages  less  carbonic  acid  than 
another  base.  You  see  then  the  ambiguity  that  there  is  in 
this  substance  by  no  means  escapes  him,  and  he  continually 
returns  to  it  as  an  enigma.  Richter,  armed  with  so  powerful 
a  principle  as  that  which  he  had  discovered,  could  not  limit 
the  application  of  it  to  his  own  labours ;  he  also  applies  it  to 
those  of  others,  and  rectifies  or  confirms  them ;  for  he  was,  so 
to  say,  endowed  with  a  sense  more  than  his  contemporaries. 

Berthollet  had  found,  as  Lavoisier  says  in  his  treatise  on 
chemistry,  that  69  parts  of  sulphur  absorb  31  parts  of  oxygen 
to  become  transformed  into  sulphuric  acid.  Richter  repeats 
the  experiment  and  comes  to  a  very  different  result.  He 
oxidates  sulphur  by  nitric  acid ;  then  converts  it  into  sulphate 
of  lime  and  obtains  947  parts  of  this  latter  for  222  of  sul- 
phur, which  makes  856  parts  for  201  of  sulphur,  whilst  we 
admit  at  present  857*1 .  He  then  greatly  approaches  the  truth, 
but  to  deduce  the  composition  of  sulphuric  acid,  that  of  the 
sulphate  must  be  known  exactly.  This  not  being  sufficiently 
well  known  to  him,  he  finds  that  201  parts  of  sulphur  absorb 
227  instead  of  300  of  oxygen  to  be  converted  into  sulphuric 
acid  (vol.  v.  p.  124),  which  compared  to  Berthollet's  result, 
is  still  a  very  beautiful  approximation,  since  this  latter  had 
only  found  90  parts  instead  of  300.  Then  he  is  reproached 
with  Bergmann's  researches  on  the  sulphates  of  potash  and 
barytes.  They  are  not  just,  he  says,  for  if  we  suppose  the 
salts  compound,  as  Bergmann  points  out,  and  if  one  of  them 
is  mixed  with  a  neutral  salt,  by  which  it  may  be  mutually  de- 
composed, there  will  be  an  excess  of  acid  or  of  base,  which 
cannot  happen;  everyone  knows  that  the  solutions  remain 
neutral  (vol.  vii.  p.  94  and  95) :  therefore  his  analyses  are  false. 

Klaproth  had  discovered  strontian*;  he  describes  and  ana- 
lyses several  of  its  salts,  without  attention  to  Richter's  prin- 
ciples. The  latter  applies  them  and  finds  that  the  analyses 
of  Klaproth  agree  with  the  principle,  and  consequently  that 
they  are  exact. 

It  is  this  very  important  discovery  which  has  been  attri- 
buted to  Wenzel.  This  question  therefore  demands  an  at- 
tentive examination ;  for,  take  this  title  from  Richter,  and  vou 
make  him  fall  back  into  the  category  of  ordinary  philosophers. 

*  [Strontian  was  first  discovered  by  Dr.  Hope;  though  its  discovery  about 
the  same  time,  or  shortly  after,  by  Klaproth,  appears  to  have  been  an  inde- 
pendent one* — Edit.] 


90  M.  Hess  on  the  Scientific  Labours  of  Richter. 

It  is  no  longer  a  summit ;  it  is  no  longer  to  him  that  the  che- 
mist owes  the  compass  without  which  he  could  not  navigate. 
Well,  not  only  does  Richter  in  his  Stochiometrie,  vol.  iii. 
p.  285,  use  this  principle  in  order  to  verify  the  results  of  his 
contemporaries,  but  even  those  of  Wenzel  are  submitted  to 
this  test.  This,  it  may  be  objected,  is  not  a  proof,  for  he  may 
not  have  quoted  the  author  from  whom  he  has  borrowed  the 
idea.  But  I  have  read  and  re-read  Wenzel,  and  not  a  word, 
not  a  trace  of  this  idea  is  to  be  found  in  his  work.  It  was 
possible  that  an  edition  reprinted  in  1800  might  be  inex- 
act; I  referred  to  that  of  1782,  and  with  the  same  result. 
Here  however  is  an  unexceptionable  proof  that  the  principle 
in  question  really  belongs  to  Richter  and  not  to  Wenzel. 
Open  Wenzel's  work,  and  you  will  find  at  the  end  a  chap- 
ter which  is  entitled  "  Applications  of  the  laws  of  affinity 
to  particular  cases"  (Anwendung  der  Lehre  von  der  Ver- 
"joandtschqft  der  Korper  auf  besondere  Falle).  This  is  the 
manner  in  which  Wenzel  expresses  himself:  "In  chemistry,  as 
in  every  other  natural  science,  the  essential  aim  is  to  compare 
recognised  facts  in  their  mutual  relation,  in  order  to  deduce 
other  truths  which  are  not  perceived  at  first  view.  In  the 
experiments  above  quoted,  we  came  to  a  knowledge  of  the 
phaenomena  which  took  place,  by  the  fact  of  the  union  of  two 
substances.  We  saw  in  what  order,  under  what  condition, 
and  in  what  proportions  they  are  combined.  The  greater  part 
however  of  these  experiments,  considered  singly,  are  not  of 
great  importance,  whilst  we  only  limit  science  to  that.  But 
they  acquire  importance  as  soon  as  we  apply  them  properly, 
for  their  merit  essentially  depends  upon  a  happy  application." 

Let  us  follow  Wenzel  in  his  applications,  and  let  us  choose 
for  this  purpose  §  7.  There  he  proposes  as  a  question  to  find 
the  simplest  and  most  advantageous  manner  of  obtaining  cry- 
stallized verdigris.  Here  is  what  he  proposes : — the  sulphate 
of  copper  and  the  acetate  of  lead  are  both  soluble  in  water; 
if  these  two  solutions  are  mixed,  the  sulphuric  acid  by  virtue 
of  its  affinity  for  the  oxide  of  lead  will  seize  upon  this  and 
form  an  insoluble  substance,  which  may  be  utilized  in  the 
arts  on  account  of  its  whiteness.  The  liquid  will  contain 
some  acetate  of  copper  which  we  separate  from  the  precipi- 
tate. Depending  upon  his  analyses,  Wenzel  calculates  the 
quantity  of  oxide  of  lead  contained  in  a  given  quantity  of 
acetate  "of  lead.  He  then  calculates  the  quantity  of  sulphate 
of  copper  necessary  to  precipitate  all  the  oxide  of  lead.  That 
done,  he  examines  the  question,  to  learn  whether  the  acetic 
acid  which  the  oxide  of  lead  has  just  left  is  sufficient  to  dis- 
solve all  the  oxide  of  copper  which  has  just  been  left  by  the 


M.  Hess  on  the  Scientific  Labours  o^  Richter.         91 

sulphuric  acid,  and  always  starting  from  his  analyses,  he  comes 
to  the  conclusion  that  the  acetic  acid  set  at  liberty  is  not  suf- 
ficient to  dissolve  all  the  oxide  of  copper,  and  that  for  the 
quantity  of  copper  employed,  which  is  124  parts,  there  will 
be  found  of  it  9j  parts  mixed  with  the  sulphate  of  lead  as  an 
oxide.  In  this  case  Richter,  starting  from  his  principle,  would 
necessarily  say,  these  analyses  are  false !  as  he  did  in  many 
cases.  What  does  Wenzel  ?  he,  on  the  contrary,  concludes 
that  after  having  separated  the  solution  from  the  precipitate, 
this  last  must  be  treated  with  a  little  sulphuric  acid  to  remove 
the  oxide  of  copper.  Here  then  is  a  very  evident  proof  that 
Wenzel  did  not  even  suspect  a  similar  relation  to  that  which 
was  discovered  by  Richter.  Richter  not  merely  discovers 
this  principle,  but  he  comprehends  it  in  its  totality;  he  follows 
it  in  all  its  consequences,  and  nothing  can  show  us  more  fully 
the  depths  of  his  convictions  with  respect  to  this,  than  some 
words  which  are  to  be  found  in  the  preface  to  the  10th  volume. 
"  The  theorems  of  stcechiometry,"  says  he,  "  contain  a  neces- 
sity; they  may  be  constructed  and  have  the  value  of  a  -priori 
principles." 

These  principles  conduct  him  to  new  generalities.  He  finds 
that  when  a  metal  is  precipitated  from  its  solution  by  another 
metal,  the  quantities  of  oxygen  necessary  to  preserve  equal 
quantities  of  the  two  metals  in  solution,  are  to  each  other  in 
the  inverse  ratio  of  the  masses  of  the  two  metals.  Further 
oh,  he  concludes,  since  when  several  metals  are  precipitated 
from  solution  by  one  another,  the  solution  always  remains 
neutral,  it  is  sufficient  to  know  the  difference  of  weight  be- 
tween one  of  these  metals  and  its  oxide,  to  deduce  from  it  the 
quantity  of  oxygen  which  all  the  others  contain  in  the  state 
of  oxide.  For  this  it  is  sufficient  to  take  a  constant  quantity 
of  the  same  acid,  for  then  all  the  metals  that  may  be  dissolved 
in  this  acid  will  contain  the  same  quantity  of  oxygen,  which 
will  then  only  have  to  be  deducted  from  the  weight  of  the 
oxide,  in  order  to  obtain  that  of  the  metal. 

Richter  takes  sulphuric  acid  for  a  starting-point,  and  pre- 
pares a  table  of  the  composition  of  the  metallic  sulphates ;  in 
this  table  the  quantity  of  oxygen  of  the  metal  being  necessarily 
constant,  he  designates  it  by  the  letter  U.  This  is  what  we 
now  designate  by  the  letter  O.  Richter  was  then  very  near 
establishing  a  system  of  equivalents,  just  like  that  which  is  at 
present  used  ;  for  that  object  it  was  sufficient  to  refer  all  the 
numbers  to  this  constant  quantity  U.  But  this  simple  idea  had 
not  struck  him,  for  in  another  column  he  gives  the  composition 
of  the  muriates,  takingjlOOO  parts  of  muriatic  acid  as  a  starting- 
point  ;  in  another  column,  indeed,  he  gives  the  composition  of 


92  M.  Hess  on  the  Scientific  Labours  of  Richter. 

the  nitrates,  taking  for  starting-point  1000  parts  of  nitric  acid. 
His  numbers  therefore  varied  continually,  which  must  have 
kept  many  relations  concealed  from  his  sight. 

Nevertheless  these  tables  constructed  by  Richter  have  an- 
other peculiarity  which  merits  our  attention.  The  names  of 
metals  are  not  found  in  them  in  writing,  but  the  signs  then  used 
are  substituted  for  them,  as  6  manganese,  $  iron,  5  zinc, 
])  silver.  But  here  signs  fail  him,  for  several  metals  had  just 
been  newly  discovered ;  these  Richter  expresses  by  the  two 
initial  letters  of  the  name,  for  example,  %g  for  chrome,  Ti  for 
titanium,  Te  for  tellurium.  Here  then  is  the  first  idea  of  the 
notation  so  happily  completed  by  M.  Berzelius. 

We  see  Richter  continually  occupied  with  the  phenomenon 
of  neutrality.  What  then  is  the  neutrality  of  a  solution  ?  This 
is  a  thoi'ny  question,  and  one  to  which,  even  at  the  present 
time,  many  authors  answer  only  in  an  obscure  and  evasive 
manner.  Neutrality,  says  Richter,  is  absolute  or  relative :  it 
is  absolute  when  the  solution  does  not  exert  any  reaction  on 
test  papers ;  it  is  relative  when  the  neutral  salt  nevertheless 
exerts  an  acid  or  alkaline  action.  But  in  this  case,  he  says, 
however  decided  may  be  the  reaction  exerted  by  a  metallic 
solution  (for  example  the  nitrate  of  silver),  you  recognize, 
nevertheless,  that  it  is  neutral,  because  the  least  addition  of  an 
alkali  causes  a  precipitate  which  will  not  dissolve  again  with- 
out adding  an  acid. 

Although  Richter  had  recognised  the  fact  that  different 
metals  required  the  same  quantity  of  oxygen  in  order  to  be 
dissolved  in  the  same  quantity  of  acid ;  notwithstanding,  he 
says,  when  metals  become  charged  with  oxygen  without  the 
intervention  of  an  acid,  that  by  no  means  prevents  them 
from  taking  very  different  quantities.  Richter,  as  we  see,  was 
not  ignorant  that  there  were  different  degrees  of  oxidation, 
and  he  employed  himself  in  determining  several  of  them. 
As,  however,  the  works  of  Richter  which  relate  to  the  oxides 
of  metals  are  far  from  being  very  exact,  let  us  examine  an 
example  in  order  to  discover  to  what  the  inaccuracies  met 
with  in  his  determinations  are  to  be  attributed. 

He  knew,  for  example,  that  arsenic  formed  two  combi- 
nations with  oxygen,  arsenious  acid  and  arsenic  acid.  He 
determines  by  a  direct  experiment  the  quantity  of  oxygen 
which  arsenious  acid  takes  to  become  converted  into  arsenic 
acid,  and  find's  that  100  parts  of  acid  absorb  17*2  of  oxygen, 
which  is  not  far  distant  from  the  real  number,  16*17.  He  after- 
wards seeks  to  determine  the  quantity  of  oxygen  which  me- 
tallic arsenic  absorbs  to  become  converted  into  arsenious  acid, 
and  he  finds  for  100  parts  of  metal  15*1  parts  of  oxygen,  de- 


M.  Hess  on  the  Scientific  Labours  of  Richter.         93 

viating  greatly  from  the  true  number,  which  is  31*9.  Having 
a  false  idea  of  the  composition  of  arsenious  acid,  he  neces- 
sarily deduces  a  false  composition  for  arsenic  acid.  Now 
this  is  the  way  he  obtains  a  number  so  far  from  the  truth : 
he  converts  a  given  weight  of  regulus  of  arsenic  into  arsenic 
acid,  and  then  into  arseniate  of  lead.  But  instead  of  drawing 
a  conclusion  from  the  weight  of  this  latter,  he  first  tries  to 
determine  the  quantity  of  arsenic  acid  which  the  precipitate 
should  contain,  and  for  that  purpose  sets  out  from  the  arseniate 
of  magnesia,  which  must  necessarily  compromise  all  the  re- 
sults ;  for  in  order  to  determine  the  composition  of  that  salt,  he 
saturates  a  solution  of  arsenic  acid  by  the  carbonate  of  magne- 
sia, a  salt  whose  composition  is  not  always  constant.  Then  he 
determines  the  quantity  of  arsenic  acid  from  a  table  of  density 
previously  constructed.  In  this  then  consists  Richter' s  greatest 
fault,  I  will  even  say  the  only  one  which  he  has  committed,  but 
from  which  several  others  originate :  he  did  not  yet  quite  ap- 
preciate the  difference  which  exists  between  a  direct  and  an  in- 
direct method.  This  is  the  true  source  of  all  his  errors.  To 
make  amends  for  this,  each  time  that  he  makes  a  direct  expe- 
riment, he  approaches  very  nearly  to  the  truth ;  for  example, 
if  he  wished  to  know  of  how  much  oxygen  and  cobalt  the  oxide 
of  this  metal  is  formed,  he  determines  this  quantity  in  a  direct 
manner,  and  finds  for  100  parts  of  cobalt  26*5  of  oxygen,  which 
does  not  widely  deviate  from  27,  which  is  the  real  number. 
But  Richter  distrusts  himself.  He  tells  us  (vol.  ix.  1798,  pre- 
amble) that  he  cannot  easily  manipulate  ;  that  he  was  never 
able  to  finish  an  analysis  without  losing  something  at  the  end 
of  all  the  operations ;  and  that  he  never  dared  to  undertake 
an  investigation  if  there  was  any  question  of  stcechiometrical 
determinations,  with  so  small  a  quantity  as  100  grains,  but  that 
he  needed  500.  This  is  perhaps  the  reason  why  Richter  at- 
tached great  value  to  the  tables  of  density,  whether  for  acids 
or  for  salts.  A  considerable  part  of  his  time  too  was  employed 
in  making  them.  At  the  end  of  each  acid  he  gives  a  table  in- 
dicating the  acid  contents  in  a  solution  at  different  degrees  of 
density.  He  does  the  same  for  the  salts  which  are  most  used. 
Richter  was  also  much  employed  at  different  times  in  con- 
structing areometers  and  alcoholometers ;  we  still  use  many 
instruments  which  bear  his  name. 

It  is  not  only  when  Richter  treats  of  general  questions  that 
he  merits  all  our  attention  ;  he  often  captivates  it  by  questions 
which  are  quite  special.  A  few  examples  will  suffice  in  order 
to  appreciate  him.  We  have  seen  that  he  confirms  the  re- 
searches of  Klaproth  on  the  composition  of  the  salts  of  stron- 
tian,  but,  he  says,  my  conclusions  are  not  just  unless  the  salt 


94  M.  Hess  on  the  Scientific  Labours  of  Richter. 

which  I  have  used  was  pure.  He  had  prepared  this  salt  by 
dissolving  the  natural  carbonate ;  the  object  in  question  then 
was  to  know  if  it  did  not  contain  lime  or  barytes.  He  finds 
that  a  solution  of  strontian  is  not  troubled  by  adding  a  solu- 
tion of  ferrocyanate  of  potash,  whilst  the  least  portion  of 
lime  or  of  barytes  may  be  discovered  by  this  means.  In  its 
turn  lime  is  distinguished  from  barytes  by  the  solubility  of  its 
sulphate.  This  work  has  been  quite  forgotten,  and  in  our 
time  a  chemist  in  high  esteem  at  Berlin  again  takes  up  the 
question,  and  supported  by  more  recent  works  gives  absolutely 
the  same  solution  of  the  problem  which  his  countryman  Rich- 
ter had  given  so  long  before  (Pogg.,  Ann.  vol.  xliv.  p.  445*). 

Richter  rinds  that  it  is  difficult  to  prepare  very  concentrated 
nitric  acid  because  of  the  great  quantity  decomposed  by  heat. 
Now  this  inconvenience  is  remedied  by  using  a  quantity  of 
sulphuric  acid  double  that  necessary  for  decomposing  the 
nitre.  Richter  proposes  another  means  which  merits  our  at- 
tention ;  he  adds  to  the  nitre  one-third  of  its  weight  of  per- 
oxide of  manganese,  and  the  quantity  of  sulphuric  acid  neces- 
sary for  decomposing  the  two  substances.  He  finds  that  the 
disengagement  of  oxygen  which  accompanies  the  distillation 
of  nitric  acid  prevents  the  formation  of  nitrous  acid. 

It  was  already  known  in  Richter's  time  that  salts  while 
passing  from  the  state  of  solution  to  that  of  crystals,  gave  out 
heat.  The  same  phenomenon  takes  place  when  water  becomes 
ice ;  it  was  therefore  thought  fit  to  indicate  the  analogy  of  the 
two  phenomena  by  saying  ice  of  crystallization,  instead  of 
water  of  crystallization,  the  term  which  had  been  used  till  then. 
Richter  puts  the  question,  whether  water  which  is  found  com- 
bined in  crystals  exists  in  them  in  the  state  of  ice  or  not. 
This  is  the  manner  in  which  he  succeeds  in  solving  this  in- 
teresting question.     He  dissolved  1440  parts  of  crystallized 

sulphate  of  soda  (NaS  +  10H);  the  temperature  of  which 
was  15°*55  C.  in  3405  parts  of  water,  the  temperature  of  which 
was  760,67  C.  The  solution  obtained  indicated  a  tempera- 
ture of  48°*96.  Supposing  that  the  capacity  of  the  elements 
for  heat  remains  the  same,  Richter  finds  that 

1440  .  15-55  +  3405  .  76'67 

—r-rz =    58'4 

4845 

should  be  the  temperature  of  the  liquid.  There  is  therefore 
a  lowering  of  temperature  of  9°'44.  He  admits  that  the  spe- 
cific heat  of  the  liquid  was  0'75,  and  that  consequently  the 

[*  A  translation  of  the  paper  (by  H.  Rose)  here  referred  to  will  be  found 
in  Phil.  Mag.  S.  3.  vol.  xiv.  p.  78.— Edit.] 


M.  Hess  on  the  Scientific  Labours  of  Richter.        95 

depression  of  temperature  observed  is  equivalent  to  that  which 
would  have  been  produced  by  the  fusion  of  457*4  parts  of  ice 
at  0°.  But  as  he  finds  that  the  1440  parts  of  salt  employed  con- 
tain, not  457  parts  of  solidified  water,  but  803  parts,  he  con- 
cludes thence  that  this  water  had  not  lost  as  much  heat  as  the 
water  should  necessarily  have  lost  in  order  to  freeze,  and  that 
consequently  it  is  not  correct  to  say  ice  of  crystallization. 

Notwithstanding  the  depth  of  his  views,  Richter  was  not 
the  less  exposed  to  critical  attacks  which  were  often  unjust. 
His  replies  were  always  not  only  moderate,  but  in  general 
as  calm  as  if  he  had  discussed  an  uncontested  subject.  When 
M  *  *  *  makes  me  such  a  reproach,  says  he,  I  bear  it  without 
thinking  myself  injured;  I  merely  believe  that  irony  does  not 
suit  the  end  which  criticism  ought  to  have  in  view  and  which 
should  be  to  convince.  Besides,  every  one  cannot  follow  an 
author  step  by  step  in  order  to  judge  with  knowledge  of  the 
subject,  for  it  is  not  sufficient,  for  this  purpose,  to  turn  over 
the  leaves  of  a  work.  Several  times  in  his  prefaces  Richter 
complains  of  not  being  read  with  attention.  Thus  to  give  an 
idea  of  the  manner  in  which  his  views  were  treated,  I  will 
mention  another  critic  (M.  Fries)  who  thought,  for  example, 
that  it  was  impossible  to  explain  why  the  elements  followed  a 
fixed  law  in  their  relations  of  neutrality.  To  that  Richter  re- 
plies, that  nature  would  be  very  poor  if  she  were  limited  only 
to  what  was  intelligible  for  him  and  for  his  criticism. 

Another  critic  asked  him  with  more  reason  to  give  a  sum- 
mary of  his  doctrine  which  might  be  comprehended  by  every 
one.  Richter's  fault  was  that  he  did  not  express  himself  clearly ; 
if  circumstances  had  caused  him  to  undergo  the  severe  disci- 
pline of  the  French  language,  if  Richter,  like  Lavoisier,  had 
drawn  his  logic  from  the  school  of  Condillac,  the  truths  which 
he  published  would  have  spread  with  more  facility,  and  he 
would  have  produced  the  same  results  with  less  labour. 

In  the  sciences,  gentlemen,  labour  is  divided  into  two  very 
distinct  categories ;  some  from  their  novelty  and  the  generality 
of  their  results  open  a  new  field  to  investigation,  and  spread 
great  truths  which  astonish  the  generation  which  sees  them 
originate.  These  works,  gentlemen,  make  an  epoch  in  the 
history  of  the  development  of  intelligence,  and  man  is  hardly 
ever  ungrateful  for  this  benefit.  Others,  sometimes  as  diffi- 
cult as  the  preceding  ones,  are  but  a  tribute  of  our  love  for 
science, — a  right  to  the  esteem  of  our  contemporaries.  They 
pursue  and  extend  paths  already  opened.  They  cause  us 
to  be  esteemed  while  we  live ;  a  certain  deference  surrounds 
us:  but  let  us  not  deceive  ourselves;  it  is  but  the  homage 
which  politeness  imposes  by  the  fact  of  our  presence,  for  after 


96    Mr.  J.  R.  Christie  on  the  Extension  of  Budan's  Criterion 

us,  a  generation  which  passes  over  our  grave  is  sufficient 
to  cause  these  titles  not  to  be  remembered;  the  facts  are 
quoted,  the  authors  are  forgotten. 

The  works  of  Richter,  as  we  have  seen,  belong  to  these  two 
distinct  classes,  and  if  it  is  true  that  a  few  words  should  suffice 
to  sum  up  the  entire  life  of  a  celebrated  man,  that  of  Richter 
is  altogether  summed  up  in  these  words  (taken  from  the  Wis- 
dom of  Solomon,  xi.  22)  which  he  placed  as  an  epigraph  at  the 
head  of  all  of  his  works  which  treat  of  chemical  proportions: 
"  God  made  all  things,  in  measure,  and  number,  and  weight." 

XVI.  On  the  Extension*  of 'Budan's  Criterionfor  the  Imaginary 
RootS)  and  a  new  Method  of  effecting  the  Separation  of  the 
nearly  equal  Roots  of  a  numerical  Equation.  By  James 
R.  Christie,  Esq.\ 

T5UDAN  has  shown  that  his  criterion  of  the  presence  of 
imaginary  roots  only  fails  when,  in  the  pair  of  roots 

a  +  /3  V*  —  1,  a  is  a  positive  proper  fraction  and  /3  is  less 
than  *5,  on  account  of  the  effect  of  his  reciprocal  transforma- 
tion being  that  of  converting  these  roots  to  the  new  form 

-~g  +  02         or  ai  ±  &  V  -1» 

wherein  ay  must,  in  the  failing  case,  be  less  than  unity. 
In  the  reduced  reciprocal  equation  these  roots  become 

and  they  may,  as  before,  be  shown  to  be  imaginary  unless  /3j 
be  less  than  *5. 

If  we  suppose  a  to  be  not  greater  than  /3,  then  — —  will  be 

the  least  value  of  the  fraction  /3X ;  but  /3  is  less  than  *5,  conse- 
quently this  value  of  /3X  must  exceed  unity.  It  appears  there- 
fore that,  in  the  case  of  a  not  greater  than  /3,  the  condition  upon 
which  the  failure  of  the  criterion  depends,  ceases  to  exist  in 
the  roots  as  they  appear  in  the  first  reduced  reciprocal  equa- 
tion. The  same  will  hold  true  if  a  does  not  exceed  /3  y  3, 
since  the  least  value  this  condition  allows  for  /3j  is  '5. 

Let  us  now  see  in  what  manner  a.  and  /3  enter  into  the  se- 
cond reciprocal  equation. 

*  It  is  proper  to  mention  that,  in  1840,  I  pointed  out  the  practical  ap- 
plication of  this  method,  in  an  example  which  was  casually  brought  under 
my  notice,  to  my  friend  and  colleague  Mr.  Davies,  who  considered  the 
then  crude  remark  as  of  sufficient  importance  to  be  inserted,  with  the 
example,  in  his  last  edition  of  Hutton's  "  Course  of  Mathematics." — 
J.  R.  C. 

\  Communicated  by  the  Author. 


for  the  Imaginary  Roots  of  an  Equation,  fyc.  97 

Supposing  that  the  variations  (which  correspond  to  those  of 
the  original  equation  whose  indications  of  roots,  real  or  ima- 
ginary, we  are  attempting  to  discover  by  aid  of  the  criterion) 

disappear  from  the  equation  in (p  +.1),  the  roots  in  the 

immediately  preceding  equation  will  be  of  the  form 


a2  +  /3*       P-  a«  +  j82 


or  «-p(a2+/32)  +  /3j/-l 

a2  4-  |S2  ' 

and  in  the  second  reciprocal  equation 

(a*  +  ff2)  .  {q  -  p  (a2  +  (?)  +  g  S^l] 

which  finally  reduces  to 

(1  -p  a)2  +  f  /32  -{l-paf+p  /32' 

Now  p  evidently  represents  the  integer  next  less  than  — - — 

a2  +  /3'2, 

to  which,  if  we  assume  a.  greater  than  *5,  the  superior  limit  is 
2;  consequently,  in  this  case,  p  =  1,  and  the  above  expression 
becomes 

q-(a2  +  /32)    +/3  4/:=! 
(1  -  a)2  +  /32 

or  an  +  0n  */^-\, 

making  «u  =  (,_a)2  +  /32  and  ft,  -  (1_a)2  +  /3*. 

It  is  easily  seen  that  /3n  decreases  with  the  value  of  a,  and 
the  lower  limit  of  its  value  will  therefore,  in  this  case,  be 

<S 
•25  +  /32' 

which  decreases  with  the  decrease  of  /3;  solving  therefore 
the  equation 

£       _.5 
.25  +  /32_    * 
we  obtain  (3  =  1  ±  *866 ;  and  since  /3  must  be  less  than  '5, 
we  have  /3  =  •  134  as  the  value  which  /3  cannot  exceed  if /3U 
is  less  than  *5. 

Should  /3U  be  less  than  '5  (^  and  un  being  greater  than  *5) 
Pfo7.  Mag.  S.  3.  Vol.  21.  No.  136.  Aug.  1842.  H 


98     Mr.  J.  R.  Christie  on  the  Extension  of  Budan's  Criterion 

two  more  reciprocal  transformations  will  give  |8iv  v'  —  l  as 
the  imaginary  part  of  the  corresponding  pair  of  roots,  (3iV  de- 
pending in  value  on  fiu  as  /3n  does  upon  /3;  we  get  therefore, 
from  the  equation  j3n  =  "134,  the  value 

/3  =-033 
as  that  which  exceeds  all  values  of  (3  which  can  make  /3iv  less 
than  *5. 

It  appears  therefore  that,  in  the  case  of  a  greater  than  *5, 
a  small  odd  number  of  reciprocal  transformations  can  hardly 
fail  to  detect  the  imaginary  roots,  supposing  «„  always  greater 
than  *5. 

Taking  now  the  case  a  not  greater  than  *5,  we  shall  obtain 
the  least  value  which  fix  can  in  this  case  hold,  by  making  in 
it  a.  =  '5;  it  becomes  then         > 

which  is  precisely  the  same  as  the  inferior  limit  to  the  value 
of /3n  in  the  preceding  case:  it  follows  therefore  from  what 
has  been  there  shown,  that  if  a  be  not  greater  than  -5  the  se- 
cond reciprocal  equation  must  detect  the  imaginary  roots,  un- 
less /3  be  less  than  *134. 

On  a  similar  hypothesis  the  third  reciprocal  equation  can- 
not fail  unless  jS,  be  less  than  *134-,  which  involves  the  con- 
dition |3  less  than  *033  :  and  so  on. 

In  thus  developing  the  changes  which  this  limit  of  |3  suc- 
cessively undergoes,  it  has  been  assumed  that  «„,  the  real  part 
of  the  imaginary  roots  in  the  nth  reciprocal  equation,  retains 
the  character  assigned  to  it  in  each  particular  case ;  but  it  is 
manifest  that  if  it  does  not  retain  its  character,  the  change 
will  only  have  the  effect  of  altering  the  hypothesis  from  u^  '5 
to  a  <  *5,  or  vice  versa. 

Independently  of  the  additional  value  which  these  consider- 
ations give  to  the  criterion  of  Budan,  there  is  yet  another  most 
difficult  case  which  the  same  operations  tend  to  elucidate,  viz. 
that  in  which  two  or  more  roots  are  nearly  equal  to  one  another. 
In  fact,  let  a  and  b  be  two  roots  very  nearly  equal,  both  of  them 
positive  and  less  than  unity,  a  condition  always  attainable ;  in 
the  first  reciprocal  equation  these  roots  will  appear  under  the 

11  7 

form  —  and  -7-,  and  their  difference  becomes r~,  greater 

a  0  a  0    ° 

than  before,  since  a  b  is  a  proper  fraction.  Now  to  whatever 
extent  the  roots  of  this  equation  are  diminished,  their  differ- 
ence is  unaltered;  if  therefore  this  difference  should  still  be 
less  than  unity,  another  reciprocal  transformation  will  again 
increase  it;  so  that  each  transformation  must  of  necessity 


for  the  Imaginary  Roots  of  an  Equation,  tyc.  99 

bring  us  nearer  to  the  point  at  which  the  roots  corresponding 
to  a  and  b  are  separable  by  means  of  unital  reductions. 
When  this  point  is  arrived  at,  we  are  at  once  enabled  to  as- 
sign the  true  values  of  the  roots  by  means  of  a  continued 
fraction,  similarly  to  the  method  employed  by  Lagrange,  as 
the  following  example  will  show. 
The  given  equation  is 

^+7^4—144.^3  +  611  x*-  928X  +  362  =  0, 
from  which  we  get  successively, 

ar15+12.r14-106.r13  +  231.r12  — 105^  —  91  =  0  {xx  s*  #-1) 
xus  +  17  xu4— 48  ^n3  -5  xn*  +  92  xn  —  58  =  0  (xn  =  x  —  2) 
xnf  +  22xm4+  30#m3-37.rm2  + 1 1  *m-l  =6(a?in  =  x-3) 

at  the  next  transformation  we  shall  evidently  lose  three  varia- 
tions; taking  therefore  the  reciprocal  equation  and  reducing, 
we  have 

yib-6yf  +  3yls  +  25yi*-10yl-26  =  o(y1  =  y-l,y=~). 

Since  this  equation  retains  the  three  variations,  there  is  every 
probability,  by  Budan's  criterion,  that  the  indicated  roots  are 
all  real.  Proceeding  with  the  reductions,  and  retaining  the 
same  notation,  we  obtain 

yn—y\  \4~l1  Vn  +  8#n2  +  30 #n  —  * 3  —  °— 3  variations. 
yin+*I/in-5ylu3-21yn*+Uyul  +  14!  =  0...2var. 

so  that  there  is  a  root  of  the  equation  in  y  between  2  and  3. 
In  continuation,  we  have 

j/iv5  +  9#iv4  +  21yiv3—  23/iv2— 22#iv  +  7  =  0... 2  variations, 
and  in  the  equation  in  yv  there  will  be  no  variations.     Again, 

therefore,  we  take  the  reciprocal  equation  in  z  =   —  and 

yiy 
continue  the  reductions : 

7V  +  13*i4— 20zj8-4"7z12-8s1  +  14.  =  0...2  variations; 
from  which  it  still  appears  that  these  roots  are  not  imaginary. 
Proceeding  as  before,  we  get 

7  z„5  +  48  *n4+ 102  zn3  +  41  2n2—  75  *n— 4-1  =  0  ...1  var. 
and  the  equation  in  zUJ  will  contain  only  permanences;  one 
root  therefore  of  the  equation  in  z  is  between  1  and  2,  and 
the  other  between  2  and  3. 

In  order  to  determine  the  actual  approximate  values  of  these 
roots  in  the  original  equation,  we  have,  by  making  y  =  2*5, 
z  =  1*5,  and  z  =  2'5,  the  three  continued  fractions, 

H2 


1 00  Mr .  J.  R.  Christie  on  the  Extension gj  Budan's  Criterion,  fyc. 

-2-1  2-1  l  ! 

*ni~  2+4-     *m  "  *  +  -J-     i    ^"-T  +  l     1 
2  1+2-  2+Y: 

whence  x  —  3'4,    .r  =  3*2 14,    a:  =  3*227. 

As  a  still  more  difficult  example  of  the  separation  of  roots 
very  nearly  equal  to  one  another,  let  us  take  the  equation 

-^—82  ^  +  2404  a3— 26394  w2  +  61 32^  —  360  =  0, 

and  it  will  be  found  that  the  following  transformations  will  be 
obtained,  viz. 

360  TOviii5  +  8268  TOvni4  +  60570  Wvm3  +  1 1 9564  Wvm2 

— 156270  WVHI  +  40335  =  0...  w  =  — , 

v 

40335  Xu6  4-  247080  x„4  +  482804  xn3  +  254274  x^ 

—88524tfii  +  6088  =  0 x  =  4—,', 

TOvm 

60883/vn6  + 124556  ,vvn4  + 758712  3/vn3  +  678342j/vn2 
—  3983874^11  +  2418165  =  Q...y  —  — , 

Xu 

241 8 165  zx6  +  8106951  V  +  8924496  V  +  30721 44  z? 

-167665*,  + 1989  =  0  z  =  —  , 

1989  *5— 167665  t4  +  3072144 13  +  8924496  t*  +  8106951 1 

+  2418165  =  0 t=   — . 

Now  it  will  be  found  that  one  root  of  this  equation  is  between 
30  and  31,  the  other  between  50  and  51,  so  that  we  have  the 
continued  fractions, 

=   —     1  =  2_ 

30+-  +S0+2 

which  give  the  values 

v  —  -118057  and  Vm  -11805649: 
the  actual  approximate  roots  to  twelve  places  are 

•118056983866  and  '118056440257. 
The  number  of  reciprocal  transformations  necessary  to  effect 
the  separations  of  the  roots,  will  of  course  primarily  depend 
upon  the  number  of  figures  in  them  which  are  identical;  but 
there  are  certain  points  in  the  scale  between  0  and  1,  from 
which,  if  the  roots  differ,  in  however  small  a  degree,  the  one 


The  Rev.  J.  Challis  on  the  Rectilinear  Motion  of  Fluids.  101 

in  excess  and  the  other  in  defect,  thejirst  reciprocal  equation 
suffices  to  show  their  inequality.  These  points  are,  evidently, 
the  reciprocals  of  the  integers  above  unity,  that  is' 

•5,      -33,      '25,      -2,      -167,      '143,  &c. 

It  would  at  first  sight  appear  that  the  least  favourable  case 
for  the  separation  of  the  roots  is  that  in  which  they  differ 
least  from  unity,  since  this  gives  its  maximum  value  to  the 

denominator  of  the  fraction  j- ;  but  it  must  be  remarked 

ao 

that  this  hypothesis  involves  the  consequence  that  the  corre- 
sponding pair  of  roots  in  the  reduced  reciprocal  equation  will 
have  their  smallest  value,  and  therefore  be  in  the  most  favour- 
able state  for  separation. 

In  order  then  to  obtain  some  general  insight  into  the  extent 
of  separation  effected  by  each  reciprocal  transformation,  we 
may  take,  as  that  of  slowest  divergence,  the  case  in  which  the 
roots  occupy  a  point  midway  between  two  of  the  above  numbers, 
and  are  as  near  to  *5  as  this  condition  will  allow.     Assuming, 

therefore,  the  roots  to  be  rather  greater  than  *41,  we  have  — -.r 

ao 

sa  6 ;  and  taking  this  number  as  the  factor  by  means  of  which 
may  be  determined  the  divergence  of  two  roots  having,  ori- 
ginally, their  difference  less  than  unity,  it  follows  that  the 
number  of  figures  in  its  wth  power  will,  not  inaptly,  represent 
the  smallest  number  of  figures  which  can  be  identical  in  the 
roots  which  become  separable  in  the  wth  reciprocal  equation. 

From  the  preceding  investigation  we  obtain  a  correct  idea 
of  the  extreme  rarity  of  the  cases  in  which  the  impossibility, 
or  the  near  equality  of  two  or  more  doubtful  roots  can  fail  to  be 
made  manifest  by  means  of  this  simple  method  of  reciprocals ; 
and  the  improbability  of  the  occurrence  of  these  cases  affords 
the  strongest  evidence  of  the  general  utility  of  the  method. 

Royal  Military  Academy,  June  13,  1842. 

XVII.  On  the  Analytical  Condition  of  the  Rectilinear  Motion 
of  Fluids.  By  the  Rev.  J.  Challis,  M.A.,  F.R.A.S.,  Plu- 
mian  Professor  of  Astronomy  and  Experimental  Philosophy 
in  the  University  of  Cambridge* . 

THE  mathematical  reasoning  which  I  gave  in  the  April 
Number  of  this  Journal  (S.  3.  vol.  xx.  p.  281)  respecting 
a  new  equation  in  hydrodynamics,  led  me  by  indirect  conside- 
rations to  the  conclusion,  that  when  ud  x  +  v  dy  +  wdz  is  a 

*  Communicated  by  the  Author. 


102  The  Rev.  J.  Challis  on  the  Analytical 

complete  differential  of  a  function  of  three  independent  varia- 
bles, the  motion  of  the  fluid  is  rectilinear.  This  theorem, 
when  once  established,  becomes  so  essential  a  part  of  analyti- 
cal hydrodynamics,  and  so  materially  affects  much  that  has 
been  written  in  this  department  of  science,  that  I  make  no 
apology  for  adding  a  direct  proof  of  it. 

Let  ar,  y,  z  be  the  coordinates  of  any  point  of  the  fluid  at  a 
given  time,  and  x  +  dx,  y  +  dy,  z  +  dz  the  coordinates  at 
the  same  time  of  another  point  distant  from  the  former  by  the 
indefinitely  small  line  d  s.  Let  ds  make  angles  a,  /3,  y  with 
the  axes  of  rectangular  coordinates,  and  let  the  direction  of 
the  velocity  V  at  the  point  xyss  make  angles  of,  /3',  7'  with 
the  same  axes,  and  an  angle  0  with  the  line  ds.  Then,  the 
components  of  V  in  the  directions  of  the  axes  being  w,  v,  w, 
we  have 

,        ,,  ,      ( u    dx       v    dy      w    dz\ 
udx  +  vdy  +  wdz  =  Vds.(-v.—  +  -v.Ts  +  v.Ts), 

=  Vds.  (cosa  cos  a!  +  cos /3  cos /3'  +  cosy  cosy')} 

=  V  ds  cos  0. 

If,  therefore,  dr  be  the  projection  of  ds  on  the  line  of  motion, 
it  follows  that 

udx-\-vdy  +  wdz=zVdr. 

This  equality  is  true  whether  the  left-hand  side  be  an  exact 
differential  or  not.  Supposing  it  to  be  an  exact  differential, 
we  might  perhaps  at  once  assert  (since  V  dr  must  be  exactly 
integrable)  that  V  is  a  function  of  x,  y,  z,  which  varies  at  a 
given  instant  by  change  of  position  from  point  to  point  of  the 
line  of  motion,  but  not  by  change  of  position  in  any  direction 
transverse  to  this;  in  other  words,  that  V  is  invariable  in 
passing  from  point  to  point  of  the  surface  of  displacement  of 
which  u  dx  +  v  dy  +  10  dz  =  0  is  the  differential  equation. 
But  that  nothing  may  appear  to  be  taken  for  granted  in  a 
question  of  so  much  importance,  I  proceed  to  prove  that  V 
must  be  a  function  of  this  kind,  in  order  that  the  three  equa- 

du      dv   du      dw    dv      din  .  .  _    . 

tl0I)S  Ty  =  d?  di  ~  d2  rfl  =  dy>  ™y  bG  Satisfiqd' 

When  the  condition  of  the  continuity  of  the  fluid  is  main-x 
tained,  the  most  general  supposition  that  can  be  made  re- 
specting the  directions  of  motion  in  an  indefinitely  small 
element  of  the  fluid,  is  that  they  are  normals  to  a  surface  of 
continued  curvature,  and  consequently  intersect  at  right  an- 
gles each  of  two  focal  lines  situated  in  the  planes  of  greatest 
and  least  curvature.     In  the  annexed  diagram  let  Ox,  Oy, 


Condition  of  the  Rectilinear  Motion  of  Fluids.         103 

O  z  be  the  axes  of  rectangular  coordinates,  and  let  the  coor- 
dinates O  M,  M  Q,  Q  P  of  the  point  P  be  x,  y,  st  and  the 


coordinates  O  m,  m  q,  qp  of  p  be  x  +  dx,  y,  z;  so  that  the 
indefinitely  small  line  Pp  is  parallel  to  the  axis  O  x.  Draw 
the  straight  lines  P  N  A,  p  n  a,  in  the  directions  of  the  motion 
at  the  points  P,  p,  at  a  given  instant.  Since  these  points  are 
supposed  to  be  indefinitely  near  each  other,  they  may  be  con- 
sidered to  belong  to  the  same  indefinitely  small  element  of  the 
fluid,  and  consequently,  by  what  has  just  been  said,  the  lines 
PNA,|)nflj  are  ultimately  normals  to  the  same  curve  sur- 
face, and  pass  through  two  focal  lines  such  as  N  n  and  A  a. 
Take  A,  the  intersection  of  P  N  A  with  the  focal  line  A  a, 
for  a  new  origin  of  rectangular  coordinates  xp  yp  zt ;  and  let 
the  axis  A  z,  coincide  in  direction  with  A  «,  the  axis  A  x,  with 
A  N  P,  and  the  axis  Ayt  be  parallel  to  N  n.  Draw  p  s  per- 
pendicularly on  A  xr  Let  A  N  =  /,  NP  =  r,  and  P  s  =  r{. 
Also  let  the  velocity  at  P  be  V,  and  that  at  the  same  time  at 
p  be  V  +  V,. 

The  component  of  the  velocity  at  P  in  the  direction  of  z 
being  w,  let  the  component  of  the  velocity  at  p  in  the  same 
direction  be  w  +  dw.     Then, 

w  =  V cos  <APQ, 
and   w  -f  d *w  =  (V  +  V,)  cos  <apqf 

=  V  cos  <apq  +  V,  cos  <  A  P  Q, 
terms  of  the  second  order  being  neglected.     Hence 

dio=  V  (cos  <ap  q  —  cos  <  A  P  Q)  +  Vy  cos  <  A  P  Q. 
Also,  d  x  =  P  s  sec  < p  P  s  =  r,  sec  <p  P  s3 

therefore 
dw  __  V  (cos  «<  a  p  g  —  cos  <  A  P  Q)  +  V/  cos  <;  A  P  Q 
d  x  ~"  rt  sec  <  p  P  s 


104  The  Rev.  J.  Challis  on  the  Analytical 

The  limiting  value  of  the  right-hand  side  of  this  equation  is 
now  to  be  found. 

Let  the  equations  of  the  three  lines  anp,  Pp,pg,  referred 
to  the  axes  A  #,,  A  y0  A  xp  be  respectively 

Then  by  known  formulas, 

cos<PPs=Vl  +  a*+b»   COS<APQ=  V\+a!*^lJ* 

1  +  ma'  -\-pd 

and         cos  <apq  =     ,— - — ,2—-W2 —  /.,   ,     2  r=? 
c  a        v  1  +  a'2  +  bu  .  v  1  +  ml  +  pl 

The  values  of  m  and  jo  may  be  found  as  follows : — Let 
A «  =  h,  and  N«  =  i.  Then  because  the  line  a np  passes 
through  the  points  a  and  w,  whose  coordinates  are  0,  0,  h,  and 
l3  kf  0,  respectively,  the  equations  (1.)  become 

I 


*l=j(h- 

;*,) 

-%) 

(4.) 


And  because  the  line  P  p  passes  through  the  point  P,  whose 
coordinates  are  r  + 1,  0,  0,  the  equations  (2.)  become 

x,=  azt+'r  +  l     \ 

*,«**,  s (5,) 

Now  the  coordinate  A  5  of  the  point  p  is  I  +  r  +  rr  Hence 
it  follows  from  equations  (5.)  that  the  other  coordinates  of  p 

are  i/,  —  — ',  and  zt  =  — .  These  values  must  satisfy  equa- 
tions (4.),  because  the  line  a  tip  passes  through  the  pointy. 
By  substituting  them  in  those  equations,  it  will  be  found  that 

—  —  =  a  ( h  1  J,  which  is  the  required  value  of  m; 

and =  ~ L ,  which  is  the  value  of  p. 

p       I  +  r  +  rj  r 

By  substituting  these  values  of  m  and  p  in  the  foregoing 
expression  for  cos  <ap  g,  expanding  and  neglecting  powers 
of  r,  above  the  first,  and  bearing  in  mind  that  1  +  a  a'  +  bb' 
=  0,  it  will  appear  that 

a1  f,       (aa'r  —  firn 


Condition  of  the  Rectilinear  Motion  of  Fluids.         105 

Hence,  cos  <a»ff  — cos <  APQ  =  — — - — - —  '     =., 

tH  ar(l  +  r)^l+an-\-yr 

We  have,  therefore,  by  obvious  substitutions, 

V(aa!r-l)  V,aa! 

dw  _        r  (r  +  I) ij 

dx      •!  +  a9  +  #"."•  1  ,+y*  +  V*' 

So  if  V2,  r2  be  the  increments  of  V  and  r,  the  coordinate  z 
only  being  supposed  to  vary,  by  exactly  the  same  reasoning 
we  shall  obtain, 

V(aa'r  —  l)  V^a'a 

du  _         r(r  +  1)  r2 

dz~  V  1  +  «*"+  bn  .    V  1  +  «2  +  62' 

If,  therefore,  —  =  -=— ,  we  must  have  — -  =  — -  • 
dz      d.z  r2       rj 

Hence,  V3  and  r3  being  corresponding  increments  of  V  and 
r  when^/  only  varies,  we  may  conclude  that 

.f  du  _dv     du_dw       ^dv_d'Wt 

dy  ~  dx9    dz~  dx*  dz      dy* 

that  is,  if  u d x  +  v dy  +  na  dz  be  an  exact  differential.  As- 
suming now  that  rx  =  r2  ==  r3,  we  shall  also  have  \,  =  V2  =  V3. 
Hence  the  increments  of  velocity  in  the  directions  of  the  axes 
of  coordinates  are  the  same,  when  the  projections  of  the 
increments  of  the  coordinates  on  the  line  of  motion  are  the 
same.  As  the  directions  of  the  axes  of  coordinates  may  be 
arbitrarily  assumed,  the  general  inference  from  this  result  is, 
that  when  udx  +  vdy+wdz  is  an  exact  differential,  the 
increment  of  velocity  from  one  point  to  another  at  a  given 
time  depends  only  on  the  change  of  position  in  the  direction 
of  the  motion;  which  it  was  required  to  prove. 

Supposing  now  that  u  dx  -f  vdy  +  ivdz  =  d <£,  that  p  is 
the  pressure  and  g  the  density  at  the  point  x  y  z,  and  that 
X,  Y,  Z  are  the  impressed  accelerative  forces  at  that  point  in 
the  directions  of  the  axes  of  coordinates,  we  have  the  known 
general  equation, 

fllP=f{Xdx  +  Ydy  +  Zdz)-d£-^+f(t), 

which,  being  differentiated  with  respect  to  space,  gives 

^  =  Xdx  +  Ydy  +  Zdz-d.d-£-VdV. 
g  *  dt 


106  The  Rev.  J.  Challis  on  the  Rectilinear  Motion  of  Fluids, 

Now,  if  the  coordinates  be  supposed  to  vary  from  one  point 
to  another  of  a  surface  of  displacement,  from  what  is  proved 

above,  dV=  0.    Alsod.-r-=  ~dt    ~7rAudx+V(ly  +  wdz) 

=  0,  because  for  a  surface  of  displacement  udx  +  vdy  +  wdz 
=  0.     Hence,  dividing  by  ds  the  increment  of  space, 

qds       \       ds  ds  ds/ 

The  left-hand  side  of  this  equation  is  the  effective  accelerative 
force  in  any  direction  perpendicular  to  that  of  the  motion. 
As  this  force  vanishes,  the  motion  must  be  rectilinear. 

It  follows  from  this  reasoning  that  the  sole  and  the  neces- 
sary condition  of  the  rectilinear  motion  of  a  fluid  is,  that  udx 
+  vdy  +  it)dz  be  an  exact  differential  of  a  function  of  three 
independent  variables. 

It  has  been  argued  by  Lagrange  in  the  Mecanique  Analy- 
tique,  that  udx  +  vdy  +  ivdz  is  an  exact  differential  when 
the  motion  begins  from  rest,  and  again,  when  the  motion  is 
so  small  that  the  squares  and  higher  powers  of  u,  v,  and  id 
may  be  neglected.  These  propositions  are  inserted  in  the 
edition  of  Poisson's  Traite  de  Mecanique  of  1811,  but  are 
omitted  in  that  of  1833.  In  the  Memoirs  of  the  Academy  of 
Paris  (tome  x.  1831),  Poisson  considers  a  problem  in  which 
that  condition  is  not  fulfilled,  though  the  motion  is  small. 
Against  the  former  of  the  above  propositions  it  may  be  urged 
that  when  u  =  0,  v  =  0,  id  =  0,  it  cannot  be  asserted  of  u  d  x 
•4-  vdy  +  tad  si  either  that  it  is  integrable  or  that  it  is  not 
integrable ;  and  against  the  latter,  that  the  integrability  of  the 
quantity  in  question  is  in  no  respect  dependent  upon  the  mag- 

nitudes  of  u,  v  and  id-  For  example,  V . d x  +  V .  - —  dy 

Z  —-  C  £  — *  C 

+  V . dz,  is  as  far  from  being  integrable  when  V  is  a 

very  small  quantity,  as  when  V  is  large.  On  this  account, 
the  cases  of  fluid  motion  in  which  udx  +  vdy  +  ivdz  is  an 
exact  differential  must  be  determined  by  considerations  inde- 
pendent of  the  magnitude  of  the  motion,  as  I  have  done  in 
this  communication. 

To  prevent  misapprehension  on  this  subject  I  may  also 
remark,  that  it  is  possible  to  assume  at  pleasure  values  of  w, 
v  and  iv,  which  will  satisfy  the  equation  of  continuity  and 
make  udx  +  vdy  +  id  d z  integrable,  and  at  the  same  time 
give  a  curvilinear  motion.  For  example,  if  u  =  m  x,  v  =  —  my 
and  id  =  0,  and  the  fluid  be  incompressible,  each  particle  moves 


Mr.  Gulliver  on  the  Minute  Anatomy  of  Animals.      107 

in  a  hyperbola.  But  in  such  cases  the  arbitrary  quantities 
introduced  by  integration  cannot  be  satisfied,  unless  the  mo- 
tion be  in  confined  spaces  or  narrow  canals,  such  that  the  co- 
ordinates in  passing  from  one  point  of  the  fluid  to  another  do 
not  vary  independently  of  each  other.  These  instances  are 
not,  therefore,  exceptions  to  the  general  rule. 
Cambridge  Observatory,  June  15, 1842. 

XVIII.  Contributions  to  the  Minute  Anatomy  of  Animals.  By 
George  Gulliver,  F.E.S.,  fyc.  fyc, — No.  II.* 

On  the  Nuclei  of  the  Blood-Corpuscles  of  the  Vertebrata. 
T>  Y  subjecting  the  blood  of  adult  mammals  to  the  slow  ac- 
-*-*  tion  of  a  very  minute  quantity  of  dilute  acetic  acid,  Dr. 
Martin  Barry  states  that  he  has  observed  nuclei  in  the  cor- 
puscles, which  he  has  depicted  in  his  recent  and  elaborate 
researches  on  the  blood  (Phil.  Trans.,  1841,  part  2).  Yet  it 
seems  fair  to  conclude  that  there  is  an  essential  difference 
between  the  blood -corpuscles  of  mammals  and  those  of  the 
lower  vertebrata,  since  the  very  same  treatment  which  never 
fails  to  show  the  nuclei  in  the  latter  will  not  exhibit  them  in 
the  former.  This,  as  I  have  elsewhere  stated  (Appendix  to 
Gerber's  Anatomy,  pp.  13  and  30),  does  not  prove  that  the 
corpuscles  of  mammals  include  no  central  matter,  although 
it  induced  me  to  believe  that  these  corpuscles  have  no  nucleus 
like  that  contained  in  the  corpuscles  of  the  lower  vertebrate 
animals. 

When  the  corpuscles  of  the  oviparous  vertebrata  are  mixed 
with  water,  or  with  dilute  or  strong  acetic  acid,  the  nuclei  are 
instantly  exposed  in  the  clearest  manner,  appearing  thick, 
oval  or  spherical,  and  much  smaller  than  their  envelopes. 
Several  other  vegetable  acids,  and  sulphurous  acid,  may  be 
used  with  the  same  effect ;  and  the  nuclei  may  also  be  readily 
shown  by  gently  moistening  with  the  breath  some  dry  blood, 
which  may  be  again  quickly  dried  so  as  to  preserve  the  nuclei 
on  the  slip  of  glass  for  future  demonstration.  But  when  the 
blood-corpuscles  of  Man  and  of  other  mammals,  not  excepting 
the  oval  discs  of  the  Camelidae  (Med.-Chir.  Trans,,  vol.xxiii., 
and  Lancet,  vol.  ii.  p.  101,  1840-41)  are  treated  by  any  of  the 
means  just  specified,  and  precisely  under  the  same  circum- 
stances, no  similar  nuclei  will  be  observed,  unless  in  very  young 
embryos ;  for  the  corpuscles  of  these  inclose  a  temporary  and 
obvious  nucleus,  which  is  probably  the  true  analogue  of  the 
persistent  nucleus  of  the  corpuscles  of  the  oviparous  vertebrata. 
In  the  Philosophical  Magazine  for  February  1840,  (S.  3. 

*  Communicated  by  the  Author.    No.  I.  will  be  found  in  p.  480  of  the 
preceding  volume. 


108  Mr.  Gulliver's  Contributions  to 

vol.  xvi.)  p.  106-107,  I  have  noticed  that  the  blood-discs  of 
mammalia  become  smaller  after  the  removal  of  their  colouring 
matter  by  repeated  additions  of  water.  Thus  some  human 
corpuscles  having  an  average  diameter  of  j^gth  of  an  inch, 
measured  only  yg^frth  after  the  whole  of  their  colouring  mat- 
ter had  been  separated  in  this  manner,  when  they  appeared 
flat  and  pellucid,  very  faint,  and  obviously  differing  in  size  and 
general  characters  from  the  particles  usually  described  as  the 
nuclei  of  the  blood-corpuscles.  No  nuclei  can  be  discerned  in 
these  washed  corpuscles,  either  by  the  aid  of  acids,  of  cor- 
rosive sublimate,  or  of  iodine. 

The  first  part  of  the  preceding  observation  agrees  in  some 
essential  points  with  the  results  obtained  by  Sir  E.  Home 
(Phil.  Trans.,  1818,  pi.  viii.  figs.  1,  2,  and  3),  Schultz  (Lan- 
cet, 1838-39,  vol.  ii.  p.  713),  and  Donne  (Mandl,  Anat.  Mi- 
cros., liv.  i.  p.  8-9). 

If  the  colouring  matter  be  in  like  manner  washed  com- 
pletely from  the  blood-corpuscles  of  the  lower  vertebrata,  both 
the  nuclei  and  envelopes  will  remain,  the  latter  becoming 
quickly  circular,  and  the  former  also  after  a  few  hours.  Sub- 
sequently the  envelopes  are  scarcely  visible,  and  the  colourless 
matter  of  the  corpuscles,  which  subsides  in  the  water,  appears 
to  be  composed  chiefly  of  the  nuclei,  although  with  the  aid  of 
iodine  many  of  the  envelopes  may  be  seen;  and  these  are  more 
or  less  reduced  in  size  after  a  few  days,  especially  in  warm 
weather.  Corrosive  sublimate  affects  them  very  feebly,  although 
it  instantly  increases  the  opacity  of  the  washed  corpuscles  of 
mammalia.  When  the  former  corpuscles  have  been  kept  some 
days  in  water,  the  envelopes  become  very  irregular,  and  hardly 
perceptible  by  any  means ;  the  size  of  the  nuclei  is  diminished, 
and  they  at  length  break  up  into  extremely  minute  molecules. 

Dilute  muriatic  acid  renders  the  nucleus  clearly  visible  in 
the  blood-corpuscles  of  the  oviparous  vertebrata.  If  the  cor- 
puscles of  a  mammal  be  treated  with  the  same  acid,  many  of 
them  appear  shrunk  and  puckered,  notched  at  the  edges,  and 
granulated ;  some  present  a  distinct  central  spot,  irregular  at 
the  margin,  like  a  granular  nucleus ;  others  remain  smooth 
at  the  circumference,  often  misshapen,  and  generally  with  a 
dark  or  brilliant  central  part,  according  to  the  focal  distance 
in  which  they  are  placed. 

The  two  following  figures  will  illustrate  the  foregoing  ob- 
servations. The  blood-corpuscles  of  man,  and  of  an  adult 
bird,  with  some  fibrine  from  the  blood  of  the  latter,  are  re- 
presented as  magnified  about  820  diameters. 

Fig.  1.  Outlines  of  blood-corpuscles  of  Man.  In  the  lower 
part  of  the  figure,  at  A,  corpuscles  in  pure  blood  from  a  prick 
of  the  finger :  some  of  them,  lying  flat,  exhibit  the  central 


the  Minute  Anatomy  of  Animals.  109 

spot,  which  others  are  without ;  several  are  seen  on  their 
Fig.  1.  Fig.  2. 


edges  collected  into  a  pile ;  of  the  two  standing  separately  on 
their  edges,  one  appears  concavo-concave,  and  the  other  con- 
cavo-convex. B.  The  corpuscles  after  thirty  hours'  washing  in 
cool  weather,  the  water  having  been  changed  until  the  whole 
of  the  colouring  matter  was  completely  removed.  These 
membranous  bases  of  the  discs  are  extremely  faint;  but,  as 
shown  at  C,  they  may  be  rendered  very  distinct  by  corrosive 
sublimate.  D.  Appearance  of  fresh  corpuscles  quickly  after 
treating  them  with  dilute  muriatic  acid :  six  of  them  extend 
horizontally  across  the  figure. 

Fig.  2.  Blood-corpuscles  and  fibrine  of  a  Goose.  At  A  is  a 
fresh  unchanged  corpuscle.  B.  Corpuscles  after  having  been 
washed  precisely  in  the  same  way  as  those  of  the  man,  but  in 
colder  weather ;  four  nuclei  are  seen,  one  of  which  appears 
to  contain  minuter  granules  or  nucleoli,  and  another  has  a 
faint  envelope.  C.  The  washed  corpuscles  treated  with  io- 
dine; some  minute  molecules  adhere  to  the  envelopes,  and 
the  nuclei  seem  to  contain  nucleoli ;  the  two  smaller  corpus- 
cles had  remained  three  or  four  days  in  the  water,  at  which 
time  many  of  the  envelopes  were  destroyed,  others  made  irre- 
gular in  size  and  shape,  and  the  nuclei  reduced  to  very  minute 
molecules.  D.  A  fresh  corpuscle  treated  with  dilute  muriatic 
acid.  E.  Two  oval  nuclei  obtained  by  dilute  acetic  acid  from 
fresh  corpuscles,  for  comparison  with  the  nuclei  which  appear 
globular  after  having  been  kept  in  water,  as  seen  at  B  and  C. 
F.  Fibrine  obtained  from  fresh  blood  by  washing  it  in  a  linen 
bag.  G.  The  same  fibrine,  in  which  a  multitude  of  oval  par- 
ticles, like  the  nuclei  of  the  blood-discs,  are  shown  by  acetic 
acid. 

On  the  Structure  of  Fibrine. 

In  the  English  version  of  Gerber's  Anatomy,  I  have  de- 


110      Mr.  Gulliver  on  the  Minute  Anatomy  of  Animals. 

picted  organic  germs,  or  objects  resembling  nucleated  nuclei, 
in  clots  of  fibrine.  Those  drawings  were  made  from  clots 
which  were  either  pale  and  opake,  or  as  transparent  and  co- 
lourless as  the  serum  of  the  blood.  I  have  lately  examined 
the  red  portions  often  found  towards  the  edges  of  such  clots, 
and  observed  in  these  coloured  parts  a  multitude  of  objects 
like  the  organic  germs  above  mentioned,  but  tinged  with  the 
colouring  matter  of  the  blood.  These  ruddy  bodies  appeared 
to  be  merely  blood-discs  entangled  in  the  fibrinous  clot  and  al- 
tered in  their  characters ;  and  hence  the  palegerms  formerly  de- 
lineated may  likewise  have  been  blood-discs  still  more  changed, 
especially  as  the  corpuscles  of  the  blood  are  regarded  as  cells 
by  Schwann,  and  cell-nuclei  by  Valentin,  while  Dr.  Barry,  as 
the  result  of  his  interesting  observations,  asks  how  many  tis- 
sues are  there  which  the  blood -corpuscles  may  not  form  r 

The  corpuscles,  of  a  yellowish  or  ruddy  hue  when  highly 
magnified,  were  contained  abundantly  in  the  coloured  fibrine : 
they  were  rather  more  irregular  in  shape  than  the  free  cor- 
puscles of  the  same  blood,  and  differed  especially  from  the 
latter  in  exhibiting  nuclei  when  washed  either  with  dilute 
or  strong  acetic  acid,  and  even  occasionally  without  the  aid 
of  any  reagent.  The  nuclei  often  appeared  as  if  flattened  and 
with  a  central  point,  and  sometimes  like  mere  granules ;  they 
were  commonly  grouped  together  in  the  centre  of  the  cor- 
puscle, frequently  separated,  and  sometimes  scattered  about 
its  circumference. 

The  following  figure  was  made  from  a  minute  red  part, 
magnified  800  diameters,  of  a  large,  white  and  very  firm  clot 
of  fibrine  from  the  heart  of  a  woman,  aged  20,  who  died  of 
puerperal  peritonitis  and  acute  pleurisy. 

Fig.  3. 


Fig.  3.  A.  A  portion  of  the  coloured  fibrinewithout  any  addi- 
tion .  The  corpuscles  are  contained  in  a  mesh  of  most  delicate 
fibrils,  such  as  I  have  formerly  described   in  clots  of  fibrine 


Mr.  Baily  on  the  Mean  Density  of  the  Earth.        Ill 

(Gerber's  Anatomy,  p.  31);  some  of  the  corpuscles,  just  like 
misshapen  blood-discs,  are  seen  on  their  edges ;  others  appear 
mottled,  and  one  exhibits  three  nuclei.  Many  minute  circular 
molecules  are  seen  in  the  fibrine ;  they  were  generally  from 
7U.lr(jotft  toTT,n^otno^an  mcn  m  dmmeter,  but  their  appearance 
has  not  been  at  all  clearly  preserved  in  the  engraving.  B.  The 
same  washed  with  dilute  acetic  acid ;  the  nuclei  of  the  corpuscles 
and  the  minute  molecules  are  distinctly  exhibited.  Several  of  the 
latter  are  attached  to  a  corpuscle  made  very  faint  by  the  acid. 
In  fibrine  obtained  by  washing  from  the  blood  of  the  ovipa- 
rous vertebrata,  there  is  also  frequently  an  appearance  of 
minute  fibrils,  as  shown  at  F,  in  fig.  2;  but  this  fibrine  is  chiefly 
characterized  by  its  containing  numerous  particles  similar  to 
and  probably  identical  with  the  nuclei  of  the  blood  corpuscles  : 
these  particles  may  often  be  seen  in  the  fibrine  without  the 
addition  of  any  reagent,  and  acetic  acid  renders  them  very 
plain,  as  at  G  in  fig.  2. 

XIX.  An  Account  of  some  Experiments  with  the  Torsion- 
rod,  for  Determining  the  Mean  Density  of  the  Earth.  By 
Francis  Baily,  Esq.,  F.R.S.,  Vice-President  of  the  Royal 
Astronomical  Society  *. 

THE  author  commences  his  account  with  a  short  prelimi- 
nary history  of  the  subject,  and  a  reference  to  the  previous 
labours  of  Maskelyne  and  Cavendish.  He  considers  the  ex- 
periments of  Maskelyne,  on  the  attraction  of  the  Schehallien 
mountain,  by  no  means  decisive  of  the  question ;  and  with  re- 
spect to  those  of  Cavendish,  by  means  of  the  torsion-rod,  he 
is  of  opinion  that  Cavendish's  object  in  drawing  up  his  me- 
moir was  more  for  the  purpose  of  exhibiting  a  specimen  of 
what  he  considered  to  be  an  excellent  method  of  determining 
this  important  inquiry,  than  of  deducing  a  result,  at  that  time, 
that  should  lay  claim  to  the  full  confidence  of  the  scientific 
world.  For,  Cavendish  himself  (who  made  only  23  experi- 
ments), in  allusion  to  this  very  point,  expresses  a  doubt  on  the 
subject,  and  hints  at  some  further  experiments  which  he  had 
in  view,  for  clearing  up  some  of  the  irregularities  which  he 
had  met  with.  But,  as  no  further  account  of  any  subsequent 
experiments  is  on  record,  and  as  no  trace  of  any  new  light  on 
this  subject  can  be  found  amongst  Cavendish's  papers,  the 
propriety  and  advantage  of  repeating  the  experiments,  under 
*  From  the  Monthly  Notices  of  the  Royal  Astronomical  Society,  having 
been  read  May  13  and  June  10,  1842'.  An  abstract  of  Mr.  Baily's  preli- 
minary paper  was  given  in  Phil.  Mag.  Third  Series,  vol.  xii.  p.  233 :  a 
notice  of  M.  Menabrea's  paper  on  Cavendish's  Experiments  will  be  found 
in  vol.  xix.  p.  62.  A  translation  of  Laplace's  memoir  on  the  mean  density 
of  the  Earth,  in  which  Cavendish's  lesults  are  examined,  was  communicated 
by  Dr.  Hutton  to  the  First  Series,  vol.  lvi.  p.  321.— Edit. 


112       Mr.  Baily's  Experiments  with  the  Torsion-rod, 

new  circumstances,  and  with  all  the  improvements  of  modern 
artists,  had  consequently  been  frequently  discussed  amongst 
scientific  persons:  and  in  the  year  1835  the  Council  of  this 
Society  appointed  a  Committee  for  the  express  purpose  of 
considering  the  subject.  No  effective  steps,  however,  were 
taken  even  by  this  body  for  carrying  the  measure  into  execu- 
tion till  the  autumn  of  the  year  1837,  when  Mr.  Airy,  the 
Astronomer  Royal  (one  of  the  Vice-Presidents  of  this  Society), 
applied  for,  and  obtained  from  his  late  Majesty's  Government, 
a  grant  of  500/.  to  defray  the  expenses  of  this  object. 

Mr.  Baily  having  offered  to  undertake  the  laborious  task  of 
making  the  proposed  experiments,  and  of  computing  the  re- 
sults, the  whole  arrangement  of  the  plan,  and  the  entire  exe- 
cution of  the  work,  was  placed  at  his  disposal  and  under  his 
control. 

It  is  somewhat  singular,  that,  whilst  this  plan  was  in  agita- 
tion in  this  country,  a  similar  course  of  experiments  had  been 
actually  undertaken  and  accomplished  by  M.  Reich,  Professor 
of  Natural  Philosophy  in  the  Academy  of  Mines,  at  Freyberg 
in  Saxony;  an  account  of  which  was  read  before  the  German 
Scientific  Association,  which  met  at  Prague  in  September 
1837;  and  an  abstract  of  the  results  was  printed  in  the 
Monthly  Notices  of  this  Society,  for  December  following*. 
Though  the  experiments  are,  on  the  whole,  in  good  accordance 
with  the  general  result  obtained  by  Cavendish,  yet  they  do 
not  interfere  with  the  plan  that  this  Society  had  in  contem- 
plation ;  which  was  not  merely  to  repeat  the  original  experi- 
ments of  Cavendish  in  a  somewhat  similar  manner,  but  also  to 
extend  the  investigation  by  varying  the  magnitude  and  sub- 
stance of  the  attracted  balls — by  trying  the  effect  of  different 
modes  of  suspension — by  adopting  considerable  difference  of 
temperature — and  by  other  variations  that  might  be  suggested 
during  the  progress  of  the  inquiry.  Reich  made  use  of  one 
mass  only,  and  that  much  inferior  in  weight  to  the  two  adopted 
by  Cavendish.  The  weight  of  Reich's  large  ball  was  little 
more  than  99  pounds  avoirdupois;  whilst  the  two  spheres, 
used  by  Cavendish,  weighed  nearly  700  pounds.  Reich's  ex- 
periments also  were  (like  Cavendish's)  too  few  in  number; 
57  only  having  been  made,  from  which  fourteen  results  have 
been  deduced  j  the  mean  of  which  makes  the  density  of  the 
earth  equal  to  5'44,  almost  identical  with  that  of  Cavendish. 

As  a  great  portion  of  the  apparatus,  which  had  been  ordered, 
was  at  this  time  actually  completed,  and  the  remainder  of  it 
in  considerable  progress,  Mr.  Baily  resolved  to  proceed  in  the 

[*  This  abstract  appears  in  Mr.  Baily's  preliminary  paper,  already  re- 
ferred to. — Edit.] 


for  determining  the  Mean  Density  of  the  "Earth.         113 

inquiry,  notwithstanding  this  apparent  confirmation  of  Caven- 
dish's results.  Various  places  were  suggested,  by  different 
persons,  as  the  most  suitable  and  fit  for  performing  experi- 
ments of  this  kind :  but,  after  inspecting  several  situations  that 
were  proposed,  and  considering  all  the  circumstances  of  the 
case,  Mr.  Baily  at  length  decided  to  carry  them  on  at  his  own 
house,  which  he  considers  to  be  not  only  the  most  convenient 
that  he  could  have  selected,  but  which  he  has  since  found  to 
be  as  suitable  and  fit  as  any  that  could  have  been  specially 
erected  for  the  express  purpose.  This  house  stands  detached 
from  any  other  building,  in  a  large  garden,  some  distance 
from  the  street,  and  consists  of  one  story  only. 

The  author  then  proceeds  to  give  a  description  of  the  room 
in  which  the  experiments  were  made,  and  likewise  of  the  ap- 
paratus that  was  constructed  for  this  special  purpose.  Al- 
though the  apparatus  was  in  a  general  view  similar  to  that 
of  Cavendish,  yet  in  some  respects  it  was  essentially  different. 
The  great  balls  (or  masses,  as  they  are  called)  were  suspended 
from  the  ceiling  by  Cavendish  and  Reich:  but  Mr.  Baily  sup- 
ported them,  from  the  floor,  on  a  plank  which  turned  on  a  pivot, 
and  suspended  the  small  balls  from  the  ceiling ;  thus  reversing 
the  mode  of  operations.  This  method  of  moving  the  masses 
he  considers  to  be  a  great  improvement :  for  he  says,  "  Nothing 
can  exceed  the  ease,  the  steadiness,  and  the  facility  with  which 
these  large  bodies  are  moved :  and  during  the  many  thousands 
of  times  that  they  have  been  turned  backwards  and  forwards, 
I  have  never  observed  the  least  deviation  from  the  most  per- 
fect accuracy.  At  the  final  close  of  all  the  experiments,  the 
pivot  turns  as  steadily,  as  freely,  and  as  accurately  as  at  the 
commencement  of  the  operations."  The  small  balls  were  also, 
by  Cavendish  and  Reich,  suspended  by  a  fine  wire  from  the 
ends  of  the  torsion-rod ;  whereas  Mr.  Baily  screwed  them  to 
the  ends  of  the  torsion-rod,  of  which  they  thus  formed  an  in- 
tegral and  solid  portion.  The  motion  of  the  torsion-rod  was 
observed  by  means  of  a  reflected  image  of  the  scale,  from  a 
small  mirror  attached  to  the  centre  of  the  torsion-rod,  in  the 
manner  proposed  by  Gauss  in  magnetical  experiments*,  and 
adopted  by  Reich.  Some  other  alterations  were  likewise  made 
in  the  construction  and  arrangement  of  the  apparatus,  to 
which  it  is  unnecessary  to  allude  more  minutely  on  the  pre- 
sent occasion. 

Mr.  Baily  made  use  occasionally  of  several  small  balls,  of 
different  sizes,  and  formed  of  different  substances,  with  a  view 

[*  See  Phil.  Mag.  Third  Series,  vol.  ii.  p.  296  :  also  Taylor's  Scientific 
Memoirs,  vol.  ii.  p.  31, — Edit.] 
Phil  Mag.  S.  3.  Vol.  2 1 .  No.  1 36.  Aug.  1 842.  I 


114         Mr.  Baily's  Experiments  "with  the  Torsion-rod 

of  ascertaining  whether  the  results  would  be  affected  by  such 
a  variation :  these  were  platina,  lead,  zinc,  glass,  ivory,  and 
hollow  brass,  varying  from  1^  inch  to  2^  inches  in  diameter. 
The  mode  of  suspension  was  also  diversified,  with  a  similar 
view:  iron,  copper,  brass,  and  silk  were  successively  used, 
not  only  single,  but  also  double,  similar  to  the  bifilar  mode 
suggested  by  Gauss*  for  certain  magnetical  experiments.  The 
mean   weight   of  each  of  the  great  balls    (or   masses)    was 
2,663,282  grains,  or  about  380|  pounds  avoirdupois,  as  de- 
termined by  the  accurate  weights  and  scales  of  the  Bank  of 
England.     And  the  weight  of  each  of  the  small  balls  varied 
from  1950  to  23,742  grains.     The  length  of  the  suspension- 
line  was  60  inches ;  and  the  length  of  the  torsion-rod  (between 
the  centres  of  the  two  balls  affixed  thereto)  was  nearly  '80 
inches.    The  torsion-rod  was  made  of  fine  deal,  of  an  uniform 
shape  throughout  its  whole  length,  and  weighed  only  about 
2300  grains.     Another  torsion-rod  was  afterwards  made,  for 
some  special  experiments,  the  weight  of  which  was  nearly  ten 
times  as  great :  it  consisted  of  a  solid  brass  rod,  and  was  oc- 
casionally used  without  any  balls  attached  to  the  ends. 

The  torsion-rod  and  the  suspension-lines  were  screened  by 
a  mahogany  box,  constructed  exactly  similar  in  form  to  that 
used  by  Cavendish,  but  supported  from  the  ceiling  in  a  very 
firm  manner,  and  unconnected  with  the  floor  or  any  other  part 
of  the  surrounding  apparatus.  Every  precaution  was  taken 
to  secure  the  torsion-rod  from  the  influence  of  any  sudden 
or  partial  change  of  temperature ;  and  also  to  insure  the  sta- 
bility and  firmness  of  the  support  to  which  it  was  attached. 
The  author's  remarks  on  this  subject  are  worthy  of  notice : 
for  he  says,  "  In  order  to  satisfy  myself  on  this  point,  at  the 
time  of  the  original  construction  of  the  apparatus,  I  made 
various  attempts  to  create  a  sensible  disturbance  in  the  mo- 
tion of  the  torsion-rod,  by  causing  the  doors  to  be  frequently 
and  violently  slammed — by  jumping  heavily  on  the  floor 
of  the  room — and  also  above  the  ceiling — and  in  other  differ- 
ent ways,  having  a  similar  tendency ;  but  in  no  instance  could 
I  observe  the  least  effect  upon  the  lateral  motion  of  the  rod. 
I  have  also  frequently  tried  the  same  experiment,  when  dif- 
ferent visitors  were  present,  since  the  apparatus  has  been  com- 
pleted ;  and  have  moreover  many  times  not  only  accidentally, 
but  also  designedly,  made  a  regular  series  of  experiments  for 
determining  the  density  of  the  earth,  during  the  most  violent 
storms  that  I  have  ever  witnessed,  when  the  wind  has  been  so 
boisterous,  and  blowing  in  such  gusts,  that  the  house  has  been 

[*  See  Taylor's  Scientific  Memoirs,  vol.  ii.  p.  252. — Edit.] 


for  determining  the  Mean  Density  of  the  Earth.        115 

shaken  to  its  centre.  But  in  no  instance  have  I  ever  seen 
the  least  disturbance  in  the  lateral  motion  of  the  torsion-rod, 
nor  any  difference  produced  in  the  results  of  the  experiments. 
I  have  thought  it  proper  to  make  these  remarks  and  thus  to 
place  them  on  record,  because  some  persons  at  first  ha- 
zarded an  opinion  that  the  place  which  I  had  selected  might 
not  be  quite  adapted  for  experiments  of  so  delicate  a  nature. 
But  a  moment's  consideration  will  convince  a  person  conver- 
sant with  the  subject,  that  no  dancing  motion  of  the  suspension- 
line  (even  if  it  did  exist)  would  tend  to  produce  an  irregular 
lateral  or  angular  motion  in  the  torsion-rod ;  and  this  is  the 
only  anomalous  motion  we  need  guard  against. 

"  There  is  also  another  remarkable  circumstance  connected 
with  this  subject,  which  I  think  it  requisite  likewise  here  to 
place  on  record.  When  the  torsion-rod  has  been  in  a  state 
of  repose,  I  have  frequently  shaken  the  torsion-box,  by  rapidly 
moving  the  ends  backward  and  forward  from  side  to  side  fifty 
or  sixty  times,  and  even  more :  but  I  could  never  discover, 
that  this  disturbance  of  the  box  caused  the  least  motion  in 
the  torsion-rod,  which  still  retained  its  stationary  position. 
This  experiment  has  been  witnessed  at  various  times  by  se- 
veral scientific  persons.  Yet,  notwithstanding  this  torpid 
state  of  the  torsion-rod,  if  the  slightest  change  of  temperature 
be  applied  near  the  side  of  the  torsion -box,  or  if  either  side 
near  the  balls  be  sprinkled  with  a  little  spirit  of  wine,  the  tor- 
sion-rod is  immediately  put  in  motion  and  the  resting-point 
undergoes  a  rapid  change." 

Notwithstanding  these  favourable  circumstances  the  author 
at  first  met  with  certain  irregularities  and  discordances,  which 
he  Tound  it  difficult  to  remove ;  and  which  appear  to  have 
been  experienced  also  by  Cavendish  and  Reich,— caused,  as 
it  is  presumed,  by  variations  in  the  temperature  of  the  room 
in  which  the  experiments  were  carried  on.  Cavendish  chose 
an  out-house  in  his  garden  at  Clapham  Common ;  and,  having 
constructed  his  apparatus  tsoitJmi  the  building,  he  moved  the 
masses  by  means  of  ropes  passing  through  a  hole  in  the  wall, 
and  observed  the  torsion-rod,  by  means  of  a  telescope  fixed 
in  an  ante-room  on  the  outside.  The  general  temperature  of 
the  interior  was  therefore  probably  uniform  during  the  time 
that  he  was  occupied  in  any  one  set  of  experiments :  but  it  is 
scarcely  to  be  expected  that  a  building  of  this  kind,  and  in 
such  a  situation,  would  preserve,  the  same  uniform  tempera- 
ture for  twenty-four  successive  hours :  especially  at  the  season 
which  he  selected  for  his  operations.  Reich  pursued  a  similar 
plan,  but  under  circumstances  apparently  more  favourable ; 
for  he  selected  a  dark  cellar,  where  the  temperature  was  not 

12 


116        Mr.  Baily's  Experiments  with  the  Torsion-rod 

so  likely  to  be  disturbed :  and,  having  closed  up  the  door,  he 
adopted  Cavendish's  plan  of  observing  the  motions  of  the  tor- 
sion-rod, on  the  outside.  But,  even  in  a  situation  like  this, 
we  must  not  expect  a  constant  uniformity  of  temperature  for 
a  long  period.  Neither  of  these  authors,  however,  has  given 
any  information  on  this  subject ;  both  of  them,  however,  met 
with  anomalies  for  which  they  could  not  satisfactorily  account : 
and,  although  Cavendish  suspected  the  cause  of  some  of  those 
anomalies,  yet  he  does  not  appear  to  have  applied  any  remedy 
for  the  evil,  in  any  of  his  subsequent  experiments. 

Mr.  Baily  remarks,  that  his  first  experiments  were  tolerably 
regular,  although  the  results  were  generally  greater  than  those 
obtained  either  by  Cavendish  or  Reich ;  but  that  he  soon  ob- 
served discrepancies  which  convinced  him  that  some  disturb- 
ing force  was  in  operation,  which  he  had  not  yet  contem- 
plated, and  which  he  sould  not  discover.  One  of  the  most 
striking  evidences  of  such  anomaly  was  the  remarkable  circum- 
stance, that  the  arc  of  vibration,  during  one  and  the  same  ex- 
periment, would  seldom  decrease  in  the  regular  manner  which 
it  ought  to  pursue,  if  the  torsion-rod  were  guided  by  an  uni- 
foi-m  influence ;  and  moreover,  that  in  fact  it  would  frequently 
z'wcrease,  contrary  to  all  the  known  laws  of  bodies  so  circum- 
stanced. Notwithstanding  these  interruptions,  he  not  only 
considered  it  proper  to  continue  the  experiments,  for  some 
time,  in  the  usual  manner,  in  the  hope  that  he  might  thereby 
eventually  throw  some  light  on  the  probable  cause  of  the 
anomalies,  and  perhaps  be  enabled  to  apply  a  correction  for 
the  effect  of  their  influence;  but  also  was  induced  to  institute 
several  new  courses  of  experiments,  as  circumstances  and  sug- 
gestions occurred,  for  the  express  purpose  of  elucidating  the 
subject.  The  theories  of  electricity,  magnetism,  temperature, 
and  currents  of  air— the  influence  of  different  modes  of  sus- 
pension by  single  and  double  wires  and  by  double  silk  lines 
— the  trial  of  balls  composed  of  different  substances  and  mag- 
nitudes— were  successively  and  frequently  appealed  to,  and 
various  experiments  made  to  discover  their  probable  effect  on 
the  results.  The  mode  of  conducting  the  experiments  was 
also  varied  in  different  ways,  with  a  view  of  eliciting  informa- 
tion on  the  point  in  question.  Some  of  them  were  carried  on 
like  those  of  Cavendish,  and  others  like  those  of  Reich  (for  the 
methods  of  these  two  experimentalists  were  very  different  from 
each  other),  whilst  many  more  were  conducted  on  a  plan  es- 
sentially different  from  either  of  them.  Heated  balls  and 
powerful  lamps  were  occasionally  applied  near  the  torsion- 
box,  with  a  view  to  raise  an  artificial  temperature,  and  thus 
create  a  powerful  influence ;  and,  on  the  other  hand,  masses 


for  determining  the  Mean  Density  of  the  Earth,       117 

of  ice  have  been  employed  for  a  similar  purpose.  The  man- 
ner likewise  of  putting  the  masses  in  motion  was  frequently 
diversified,  under  the  hope  of  being  enabled  thereby  to  obtain 
a  clue  to  the  object  of  research.  But  the  author  has  consi- 
dered it  needless  to  proceed  with  a  detail  of  these  fruitless 
operations,  which  were  carried  on,  without  much  interruption, 
for  upwards  of  eighteen  months,  and  amounted  in  number  to 
nearly  1300  experiments.  Many  of  these  were  of  a  mere  spe- 
culative nature,  with  a  view  to  discover  the  cause  of  the  ano- 
malies here  alluded  to;  but  a  thousand  of  them,  at  least,  were 
more  especially  made  for  the  purpose  of  determining  the  den- 
sity of  the  earth,  and  were  eventually  reduced.  But  the  re- 
sults, although  in  many  cases  very  consistent  amongst  them- 
selves, were  upon  the  whole  so  discordant  and  unsatisfactory, 
that  no  confidence  could  be  placed  on  the  general  result,  as  a 
correct  value  of  the  true  object  of  inquiry.  And,  as  he  had 
pre-determined  not  to  select  merely  those  experiments  which 
might  appear  to  be  the  most  favourable  specimens,  or  sup- 
porting any  particular  theory,  and  to  keep  out'  of  view  and 
reject  the  rest,  he  consequently  abandoned  the  whole. 

During  these  investigations  the  author  was  frequently  visited 
by  several  scientific  persons  who  took  a  lively  interest  in  the 
pursuit  in  which  he  was  engaged,  and  who  kindly  offered  him 
their  opinion  and  advice  on  several  occasions.     But  he  re- 
marks, that  he  was  principally  indebted  to  Professor  Forbes 
of  Edinburgh,  for  the  most  satisfactory  removal  of  the  prin- 
cipal anomalies  that  he  had  met  with.     This  gentleman's  in- 
timate acquaintance  with  the  theory  of  heat,  and  its  various 
operations,  effects,  and  influence,  led  him  to  agree  with  Caven- 
dish in  opinion,  that  one  source,  at  least,  of  the  anomalies 
might  arise  from  the  radiation  of  heat  from  the  masses,  when 
they  were  brought  up  to  the  sides  of  the  torsion-box :  and 
that  this  might  even  still  operate  notwithstanding  the  inter- 
position of  the  sides  of  the  box,  and  the  precautions  already 
taken.     As  a  remedy  for  this  influence  he  suggested  the  pro- 
priety of  having  the  masses  gilt,  and  also  of  procuring  a  gilt 
case,  as  a  cover  to  the  torsion-box,  for  the  purpose  of  pre- 
venting the  effect  of  radiation,  from  whatever  source  it  might 
arise.     Acting  upon  this  advice,  Mr.  Baily  not  only  caused  a 
gilt  case  to  be  made  in  the  manner  here  proposed,  but  also 
caused  the  torsion-box  itself  to  be  previously  covered,  all  over, 
with  thick  flannel.     These  and  other  alterations  and  improve- 
ments having  been  completed,  the  author  resolved  to  com- 
mence a  7iew  series  of  experiments,  that  were  likely  to  be  thus 
made  under  more  favourable  auspices,  for  the  correct  deter- 
mination of  the  mean  density  of  the  earth :  and  it  appears 


118        Mr.  Baily's  Experiments  with  the  Torsion-rod 

that  the  results  soon  convinced  him  that  the  proper  mode  had 
been  taken  for  the  removal  of  the  principal  source  of  discord- 
ance. For  although,  in  some  cases,  slight  discrepancies  may 
still  appear  to  exist,  as  might  be  expected  in  any  inquiry  that 
involves  so  delicate  a  system  of  operations,  yet  where  the  dis- 
cordances are  of  greater  magnitude  they  seem  to  be  confined 
to  one  class  of  experiments,  and  to  depend  principally  on  the 
nature  and  construction  of  the  material  of  which  the  suspen- 
sion-line or  torsion-rod  is  composed,  and  do  not  materially 
affect  the  general  result  of  the  whole.  In  fact,  Mr.  Baily  states 
that  he  has  since  met  with  very  few  experiments,  made  in  the 
regular  mode  of  proceeding,  that  are  objectionable,  or  that 
need  be  rejected.  Every  experiment  therefore  that  has  been 
made,  under  this  new  arrangement  of  the  apparatus  (whether 
good,  bad,  or  indifferent),  has  been  recorded  and  preserved; 
and  they  are  all  given  without  any  reserve  whatever ;  it  being 
left  to  the  reader  himself  to  reject  or  retain,  at  his  pleasure, 
such  as  he  may  think  fit. 

After  these  introductory  remarks,  the  author  proceeds  to 
the  several  modes  of  carrying  on  the  regular  system  of  opera- 
tions which  he  had  undertaken.  With  respect  to  the  torsion- 
rod,  he  states  that  it  is  never  at  absolute  rest,  but  is  constantly 
in  a  state  of  vibration  on  its  centre ;  and  consequently  when 
the  end  of  it  is  viewed  at  a  distance  with  the  telescope,  it  ap- 
pears to  oscillate  on  each  side  of  a  mean  point,  called  the 
resting-point.  For,  even  when  it  is  apparently  in  a  state  of 
complete  repose,  minute  vibrations  are  always  perceptible  with 
the  telescope  ;  and  the  times  of  performing  such  infinitesimal 
arcs  correspond,  in  most  cases,  very  nearly  with  the  mean 
time  of  vibration  that  takes  place  when  the  torsion-rod  is  in 
full  action.  Mr.  Baily  however  observes,  that  this  resting-point 
is  by  no  means  permanent  or  stationary,  and  seldom  remains 
in  the  same  position  for  any  length  of  time,  even  when  the 
torsion-rod  is  not  influenced  by  the  approach  of  the  masses. 
The  extent  and  direction  of  its  disturbance,  as  well  as  its  rate 
of  motion  when  so  disturbed,  are  very  variable,  and  seem  to 
depend  on  causes  which  have  not  been  sufficiently  accounted 
for,  but  which  may  in  some  measure  arise  either  from  slight 
changes  of  temperature,  or  some  latent  alteration  in  the  com- 
ponent parts  of  the  suspension-line.  These  vibratory  motions 
of  the  resting-point  (which  must  be  carefully  distinguished 
from  the  regular  vibratory  changes  in  the  position  of  the 
torsion-rod  itself,  caused  by  the  near  approach  of  the  masses) 
do  not  materially  affect  the  mean  results  in  a  series  of  experi- 
ments ;  more  especially  if  their  march  be  regular.  It  is  only 
when  any  sudden  and  considerable  transition  takes  place,  that 


for  determining  the  Mean  Density  of  the  Earth.        119 

a  sensible  and  material  error  is  likely  to  occur :  but  this  sel- 
dom happens  if  due  precaution  has  been  taken  to  screen  the 
torsion-box  effectually.  Yet  the  author  is  still  of  opinion  that 
discordances  sometimes  arise  which  cannot  wholly  be  attri- 
buted to  change  of  temperature,  but  to  some  other  occult  in- 
fluence with  which  we  are  at  present  unacquainted.  The  re- 
gular march  of  the  resting-point  of  the  torsion-rod  is  one  of 
the  most  important  objects  of  attention ;  since  any  considerable 
deviation  therefrom  is  the  source  of  great  discordance,  and 
therefore  requires  to  be  watched  with  care. 

The  torsion  force  comes  next  under  consideration.  Mr. 
Baily  justly  remarks  that  the  torsion  force  of  a  wire  is  that 
elastic  power  in  the  body,  by  means  of  which  it  is  enabled  to 
return  to  its  original  position,  after  being  drawn  aside  by  any 
external  impulse.  It  varies  with  the  substance,  magnitude, 
and  length  of  the  wire ;  but  it  is  generally  considered  to  be 
constant  for  the  same  wire,  whatever  be  the  weight  suspended 
thereto.  This,  however,  must  be  taken  within  certain  limits, 
since  the  time  of  vibration  (which  is  one  of  the  elements  for 
determining  the  force  of  torsion)  will  frequently  differ  very 
considerably  without  any  apparent  or  sensible  alteration  in 
the  component  parts  of  the  apparatus.  For  the  author  states 
that  we  frequently  have  in  the  same  hour  very  considerable 
variations  in  the  time  of  vibration,  which  evidently  show  that 
the  force  of  torsion  has  undergone  some  sensible  change.  But 
this  alteration  in  the  torsion  force  does  not  appear  to  affect 
the  results  of  the  experiments,  since  we  find  that,  when  the 
time  increases,  the  deviation  is  also  increased  in  due  propor- 
tion. The  magnitude,  therefore,  of  the  force  of  torsion  is  not 
a  necessary  object  of  inquiry  in  these  investigations. 

The  only  two  objects  requiring  close  attention,  for  the  pur- 
pose of  obtaining  results  from  any  of  the  experiments,  are  the 
determination  of  the  mean  resting-point  of  the  torsion-rod,  and 
the  time  of  its  vibration.  Now,  it  fortunately  happens  that 
these  two  objects  can,  in  all  cases,  be  observed  with  the  greatest 
ease  and  accuracy,  however  anomalous  they  may  be;  and 
they  are  never  accompanied  with  any  doubt  or  difficulty. 
There  is  however  another  subject  that  is  required  also  to  be . 
accurately  ascertained  in  every  experiment ;  namely,  the  ex- 
act distance  of  the  centre  of  the  masses  from  the  centre  of  the 
balls.  This  has  been  effected  by  means  of  plumb-lines,  which 
abut  against  the  masses,  and  the  distances  between  which 
are  measured,  at  every  experiment,  by  means  of  a  micro- 
scopical apparatus,  carefully  adjusted. 

From  the  results  of  the  several  experiments  that  the  author 
has  made,  it  would  appear  that  single  wires,  of  different  dia- 


120        Mr.  Baily's  Experiments  with  the  Torsion-rod 

meters,  give  slight  differences  in  the  results.  But,  he  states 
that  the  most  discordant  results  occur  where  the  double  sus- 
pension-lines are  formed  of  silk ;  and  he  apprehends  that  these 
anomalies  have  arisen  from  the  circumstance  that  all  the  fibres, 
of  which  the  skein  is  composed,  are  not  equally  stretched  by  the 
different  balls  as  they  are  successively  attached  to  the  torsion- 
rod;  and  that  they  are  thus  severally  operated  on  by  different 
forces,  which  consequently  produces  a  discordancy  in  the  re- 
sults. These  discordances,  however,  appear  to  be  generally 
confined  within  certain  limits. 

The  author  then  gives  a  detailed  account  of  the  various  ex- 
periments that  he  has  made,  under  the  improved  form  of  ap- 
paratus, which  amount  in  the  whole  to  2153;  and  which  were 
pursued  and  conducted  in  different  ways,  for  the  purpose  of 
throwing  some  light  on  the  slight  discrepancies  that,  in  spite 
of  his  care  and  caution,  would  occasionally  intrude  themselves. 
It  would  be  impossible  in  an  abstract  like  this  to  give  a  mi- 
nute detail  of  the  several  modes  that  were  adopted  in  carrying 
on  these  operations,  and  which  must  therefore  be  left  unex- 
plained till  the  work  itself  is  published.  But  the  following 
short  synoptical  view  will  enable  the  reader  to  form  an  esti- 
mate of  the  general  results  obtained  from  the  different  balls, 
according  to  the  manner  in  which  they  have  been  successively 
suspended.  The  seven  different  balls  employed  are  arranged, 
in  the  first  column,  in  the  order  of  their  weight ;  and  the 
number  of  experiments  made  therewith,  together  with  the 
mean  resulting  density  therefrom,  is  classed  in  the  three  col- 
lateral columns,  according  as  the  suspension  was  formed  of 
double  silk  lines,  double  metal  wire,  or  single  copper  wire. 
The  three  detached  series,  at  the  bottom  of  the  table,  contain- 
ing 149  experiments,  will  be  presently  explained. 


Balls. 

Double  silk. 

Double  wire. 

Single  wire. 

No. 

Density. 

No. 

Density. 

No. 

Density. 

148 

218 

89 

46 

162 

158 

99 

5-60 
'5-65 
5-66 

5-72 
573 

5-78 
5-82 

130 
145 

20 

170 

162 

5-62 
5-66 

5-6*8 
571 
570 

57 

162 
86 
92 
40 

20 

5-58 
5-59 
5-56 
5-60 
5-61 

5-79 

1^-inch  platina  ... 
[ivory  .... 

2f-inch  lead,  with 
2-inch  lead,  with  b 
Brass  rod,  alone 

44 
49 
56 

5-62 
5-68 
5.97 

It  cannot  be  supposed,  amongst  such  a  number  of  expert- 


for  determining  the  Mean  Density  of  the  Earth.        121 

merits,  prosecuted  in  such  a  variety  of  ways  and  with  such 
different  materials,  that  the  several  mean  results,  obtained 
from  the  individual  classifications,  can  be  of  equal  weight. 
In  fact,  the  author  himself  has,  in  his  investigations  of  the 
subject,  clearly  shown  that  some  of  them  are  entitled  to  more 
confidence  than  others ;  and  moreover  that,  in  a  few  instances, 
there  may  be  a  fair  cause  for  rejection.  On  these  points  how- 
ever there  is  no  room  for  explanation  in  this  place:  and  it 
may  be  sufficient  here  to  state,  that,  assuming  every  experi- 
ment to  be  of  equal  weight,  the  mean  result  of  the  whole 
2004-  experiments  is  5'67.  Nor  is  there  much  probability  that 
the  result  of  this  immense  number  of  experiments  will  be  ma- 
terially altered,  even  if  those  few  experiments,  which  may 
appear  to  be  affected  with  some  source  of  error  or  discord- 
ance, should  be  wholly  omitted. 

The  author  remarks  that  it  cannot  escape  observation  that 
the  general  mean  result,  obtained  from  these  experiments,  is 
much  greater  (equal  to  ^jth  part)  than  that  deduced  either  by 
Cavendish  or  Reich,  who  both  agreed  in  the  very  same  quan- 
tity, namely,  5*44 :  but  he  does  not  assign  any  probable  cause 
for  this  discordance.  It  is  evident,  however,  from  the  detail 
which  he  has  given  of  his  own  experiments,  that  perceptible 
differences  not  only  arose  according  to  the  mode  in  which  the 
torsion-rod  was  suspended,  but  also  depended  on  the  materials 
of  which  the  suspension-lines  were  formed :  but  it  is  somewhat 
singular  that  none  of  the  mean  results,  in  any  of  these  classi- 
fications, are  so  low  as  that  obtained  by  the  two  experiment- 
alists above  mentioned. 

In  these  remarks,  no  notice  has  yet  been  taken  of  the  re- 
maining 149  experiments  that  have  been  made  with  the  brass 
torsion-rod;  a  class  of  experiments  that  were  undertaken  for 
the  express  purpose  of  ascertaining  the  effect  of  such  a  mea- 
sure on  the  general  result.  This  torsion-rod  was  nearly  of  the 
same  weight  as  the  two  2-inch  lead  balls,  and  about  half  the 
weight  of  the  two  2|-inch  lead  balls.  The  experiments  were 
made  not  only  with  each  of  these  balls  successively  attached  to 
the  rod,but  also  with  the  rod  alone,  without  anything  attached 
thereto.  The  results  show  that  the  attraction  of  the  masses 
on  the  rod  should  be  diminished  about  ^th  part,  in  order  to 
render  these  three  several  results  consistent  with  each  other, 
and  also  accordant  with  the  same  balls  and  the  same  mode  of 
suspension,  attached  to  the  lighter  wooden  torsion-rods. 


[  122  ] 

XX.    Note  on  Mr.  Earnshaw's  Paper  in  Phil.  Mag.  for 
April  1842.     By  Professor  Powell. 

To  the  Editors  of  the  Philosophical  Magazine  and  Journal. 
Gentlemen, 
T  DID  not  happen  to  see  your  Number  for  April  till  a  few 
days  ago,  or  I  should  long  before  this  have  addressed  to 
you  the  very  brief  remarks  which  I  now  feel  called  upon  to 
offer  in  consequence  of  certain  observations  in  a  paper  inserted 
in  the  Number  referred  to,  (S.  3.  vol.  xx.  p.  304)  "  On  the 
Theory  of  the  Dispersion  of  Light,"  by  Mr.  Earnshaw. 

I  am  truly  glad  to  see  that  a  mathematician  of  such  emi- 
nence has  felt  interested  in  the  subject,  and  has  given  his  at- 
tention to  what  I  have  published  upon  it :  there  is  nothing  I 
more  desire  than  fair  discussion :  no  one  can  have  read  my 
treatise  on  the  Dispersion,  I  trust,  without  perceiving  that  I  am 
no  prejudiced  undulationist,  and  that  so  far  from  asserting 
that  that  theory  has  explained  the  dispersion,  I  on  the  con- 
trary expressly  point  out  the  extent  to  which  it  does  apply, 
and  the  precise  degree  and  nature  of  its  failure*  So  far  then 
Mr.  Earnshaw  and  myself  are  quite  agreed. 

But  in  the  mode  in  which  he  sets  about  the  more  particular 
proof  of  this  assertion,  there  are  I  confess  several  particulars 
which  strike  me  as  being,  to  say  the  least,  extraordinary  over- 
sights on  the  part  of  so  able  a  mathematician,  who  seems  to  have 
read  my  treatise,  though  I  can  only  imagine,  too  cursorily  to 
perceive  wherein  it  differs  from  certain  earlier  researches,  on 
a  reference  to  which  his  whole  objections  seem  founded. 

More  precisely :  Mr.  Earnshaw  points  out  certain  imper- 
fections in  a  formula  which  he  assumes  as  that  I  have  adopted 
for  the  dispersion  ;  he  contends  that  this  formula  is  theoreti- 
cally defective,  and  also  that  it  is  discordant  with  the  results 
of  observation  ;  and  enormously  so  in  the  case  of  the  more 
highly  dispersive  media. 

Now  all  this  is  precisely  'what  I  have  stated  in  my  work  on 
Dispersion,  where  (in  section  vi.)  he  and  your  readers  will 
find  the  nature  of  the  formula  fully  discussed;  the  formula  on 
which  he  has  commented  being  avowedly  but  an  approximate 
one,  which  applies  nearly  for  low  dispersive  substances,  and 
which  I  so  applied  in  my  earliest  researches,  but  which  I  long 
since  discarded  for  a  more  accurate  one.  This  simple  circum- 
stance then  renders  all  his  elaborate  criticisms  superfluous. 
My  published  volume  contains  my  latest  view  of  the  whole 
subject,  and  supersedes  all  my  previous  researches ;  while  it  in- 
vestigates the  entire  series  of  experimental  results  by  one  uni- 


Note  on  Mr.  Earnshaw's  paper,  Phil.  Mag.  April  1842.    123 

form  and  exact  method  derived  from  a  formula  similar  indeed 
to  that  referred  to  by  Mr.  Earnshaw,  but  in  which  the  very 
imperfections  pointed  out  by  him  are  expressly  corrected* 

As  to  the  discrepancies  between  observation  and  theory  in 
the  higher  cases  of  dispersion,  I  do  not  consider  them  as 
nearly  so  serious  as  Mr.  Earnshaw  appears  to  do ;  and  this 
mainly  from  the  experience  I  have  had  in  ascertaining  the 
experimental  numbers,  and  the  degree  of  accuracy  to  which 
they  can  be  relied  on, — for  which  1  would  refer  to  my  Report 
presented  to  the  British  Association  on  refractive  indices. 

Thus  much  however  is  clear :  the  formula  even  in  the  ex- 
treme cases  agrees  as  well  as  I  think  can  be  expected  with 
observation,  provided  one  of  the  constants  receive  a  certain  em- 
pirical change  in  its  value,  constant  for  each  medium. 

It  will  therefore  be  the  next  step  for  theory  to  investigate 
whether  such  a  change  can  be  justified;  but  all  this  I  have 
stated  at  large  in  my  work,  at  the  conclusion. 

Mr.  Earnshaw  enters  also  upon  the  question  of  the  logic  of 
the  case,  and  the  sitfficiency  of  what  is  merely  an  interpola- 
tion ;  three  indices  being  assumed.  This  point  again  I  had, 
I  thought,  fully  discussed  (p.  84  et  seq.);  at  all  events,  the 
formula,  in  whatever  manner  calculation  be  applied  to  it,  is 
surely  a  direct  deduction  from  theory.  In  particular,  the  very 
simple  form  in  which  I  have  used  it,  is  that  deduced  by  Sir 
W.  R.  Hamilton  by  a  highly  elegant  analysis  directly  from 
the  principles  of  M.Cauchy,  and  to  that  pre-eminently  gifted 
mathematician  it  appeared  a  sufficient  basis  for  calculation,  as 
was  evinced  by  his  own  use  of  it,  to  which  I  have  referred, 
Art.  261. 

Upon  the  whole,  I  will  merely  add  an  expression  of  my 
satisfaction  that  the  subject  has  been  taken  up  by  Mr.  Earn- 
shaw, and  my  hope  that  in  his  hands  some  formula  will  even- 
tually be  elicited  which  may  be  found  applicable  to  the  results 
of  observation  to  such  an  extent  as  to  clear  up  the  discre- 
pancies which  hang  over  the  existing  investigations ;  in  which 
I  am  well  satisfied  to  have  made  a  first  approximation,  if  it 
lead  to  more  accurate  results  from  the  reseaixhes  which  I 
may  thus  have  excited  more  able  analysts  to  undertake. 

I  am,  Gentlemen, 

Your  most  obedient  Servant, 

Oxford,  July  8,  1842.  -  BaDEN  PoWELL. 


[    124    ] 

XXI.  Reply  to  some  Objections  against  the  Tlieory  of  Molecu- 
lar Action  according  to  Newton's  Law.  By  the  Rev.  P. 
Kelland,  M.A.,  F.R.SS.  L.  $  E.,  F.C.P.S.,  %c,  Professor 
of  Mathematics  in  the  University  of  Edinburgh,  late  Fellow 
and  Tutor  of  Queen's  College,  Cambridge*. 
Y\THEN  I  wrote  my  reply  to  an  anonymous  correspondent 
**  in  the  Phil.  Mag.  (S.  3.  vol.  xx.  January  1842,  p.  8),  I 
did  not  contemplate  extending  my  remarks  beyond  the  limits 
of  the  objections  before  me.  But  finding,  as  well  from  the  pri- 
vate communications  of  my  friends,  as  from  what  has  ap- 
peared in  your  Journal,  that  silence  is  construed  into  an  ad- 
mission of  the  indefensibility  of  the  Newtonian  law  as  applied 
to  molecular  actions,  I  am  induced  most  reluctantly  to  enter 
on  the  defence  of  the  hypothesis.  The  following  remarks  are 
the  substance  of  a  paper  which  I  read  before  the  Philosophical 
Society  of  Cambridge  in  1840,  but  which,  from  my  extreme 
dislike  to  controversy,  I  never  printed.  Nor  should  I  have 
now  done  so,  but  for  the  expressed  opinion  of  two  of  the  first 
mathematicians  in  Europe,  whom  I  am  proud  to  number 
amongst  my  friends,  both  of  whom  have  united  in  urging  me 
either  to  remove  the  difficulties  which  attend  the  theory,  or  to 
point  out  in  what  way  they  may  be  regarded  as  not  subversive 
of  its  truth.  It  shall  be  my  endeavour  in  what  follows  to  argue 
with  perfect  candour,  not  against  the  objections  so  much  as 
for  the  theory.  I  hope  nothing  I  shall  say  will  induce  any 
one  to  imagine  that  I  undervalue  the  importance,  or  the  in- 
genuity of  the  objections  themselves,  or  that  I  lightly  esteem 
the  memoirs  in  which  they  are  embodied.  Let  it  be  under- 
stood that  I  do  not  attempt  to  overthrow  the  arguments  of 
my  opponents  to  any  extent  further  than  as  they,  if  admitted, 
would  subvert  a  theory  in  which  I  am  deeply  interested,  and 
which,  indeed,  I  partly  originated  f. 

Before  I  enter  on  my  subject  I  wish  to  state  expressly  what 
is  the  hypothesis  itself  which  I  am  about  to  defencL  It  is  this: 
That  bodies  consist  of  molecules,  simple  or  aggregated  in  groups, 
surrounded  by  particles  ofafiuid  which  pervades  all  space.  Both 
the  former  and  the  latter  molecules  are  endued  with  attractive 
or  repulsive  forces  towards  each  other,  and  each  system  likewise 
attracts  or  repels  the  particles  of  the  other.  The  law  of  force 
in  all  cases  is  that  of  the  inverse  square  of  the  distance. 
*  Communicated  by  the  Author. 

+  M.  Mossotti's  paper  was  printed  at  Turin  in  1836  j  mine  was  read 
in  February  of  the  same  year.  [M.  Mossotti's  paper  was  scarcely  known  in 
this  country,  until  its  contents,  especially  as  bearing  upon  the  theory  of 
electricity,  were  announced  by  Mr.  Faraday  at  the  Royal  Institution,  on  the 
20th  of  January  1837  (see  Phil.  Mag.  S.3.  vol.  x.  p.  84,  317) :  a  transla- 
tion of  the  entire  paper  appeared  in  Taylor's  Scientific  Memoirs,  (vol.  i. 
p.  448)  on  the  1st  of  February.— Edit.] 


Theory  of  Molecular  Action  according  to  Newton's  Law.    125 

In  what  way  the  alternative  of  attraction  or  repulsion  is  de- 
fined, I  do  not  profess  accurately  to  specify.  I  prefer,  for 
the  present,  to  consider  matters  of  detail  as  open  for  future  in- 
vestigation. That  I  may  be  allowed  to  do  so  it  is  necessary 
that  I  should  premise  the  grounds  on  which  I  consider  them 
as  not  yet  satisfactorily  established.  Whether  the  molecules 
of  matter  attract  or  repel  each  other  is  perfectly  indifferent ; 
I  believe  either  hypothesis  will  do  very  well.  Neither  does 
it  signify  whether  the  particles  of  matter  attract  or  repel  those 
of  the  other  fluid  (called  aether),  provided  it  be  allowed  that 
the  latter  can  come  in  contact  with  and  rest  against  the  former. 
But  whether  the  particles  of  aether  attract  or  repel  each  other 
is  a  question  of  more  importance,  and  one  which,  when  de- 
cided, will  probably  settle  the  other  two.  The  prima  facie 
probability  is  that  they  act  by  repulsion.  It  is  argued  in 
favour  of  this  supposition,  that  were  it  not  so,  the  slightest 
displacement  which  should  bring  two  particles  near  each  other 
would  of  necessity  cause  them  to  run  together.  That  this 
argument  is  fallacious  will  appear  presently,  when  we  shall 
show  that  they  would  not  instantaneously  tend  either  to  unite 
or  to  separate.  Another  argument  is  that  when  they  had 
once  come  in  contact  they  could  never  again  be  separated. 
This  argument  applies  with  equal  force  against  any  hypothesis 
of  attractive  particles.  At  the  same  time  I  do  not  think  the 
arguments  in  favour  of  the  hypothesis  of  attraction  to  be  by 
any  means  conclusive. 

The  popular  grounds  on  which  I  rested  this  hypothesis 
(Trans.  Camb.  Phil.  Soc.  vol.  vi.  p.  178)  can,  of  course,  only 
be  held  as  an  illustration.  That  they  are  quite  insufficient  to 
build  anything  upon,  is  obvious  enough ;  but  it  is  most  com- 
pletely shown  by  Mr.  Earnshaw  in  his  memoir  on  the  Nature 
of  Molecular  Forces,  to  which  I  am  about  to  direct  attention 
presently.  (See  Art.  8.)  Nor  is  the  argument  deduced  from 
an  approximate  estimation  of  the  value  of  the  function  which 
expresses  the  time  of  vibration  of  a  particle,  at  all  conclusive. 
It  will  be  found  in  my  memoir  (Trans.  Camb.  Phil.  Soc.  vol.  vi. 
p.  183  and  24-1).  It  rests  on  the  assumptions,  first,  that  the 
principal  effect  is  due  to  the  particles  in  the  immediate  neigh- 
bourhood of  that  whose  motion  we  are  ihvestigating ;  secondly, 
that  the  effect  of  the  action  of  any  particle  is  independent  of 
its  position  relative  to  the  direction  of  transmission.  The 
former  assumption  is  doubtless  admissible  to  a  certain  extent ; 
the  latter,  I  believe,  not  at  all.  The  attractive  nature  of  the 
particles  is  still  further  supported  by  an  argument  which  I  do 
not  now  regard  as  satisfactory.  It  is  this: — We  have  good 
reason  to  suppose  that  the  vibrations  of  the  air  are  normal,  in 


126     Prof.  Kelland's  Reply  to  some  Objections  against  the 

the  production  of  sound ;  we  are  certain  that  the  particles  of 
air  act  repulsively  on  each  other :  our  analysis  shows,  that  if 
repulsive  forces  produce  normal  vibrations,  attractive  forces 
must  act  to  produce  the  transverse  ones  which  constitute  light. 
There  are,  however,  two  things  connected  with  the  mutual 
action  of  the  particles  of  air,  which  are  here  left  out  of  the 
account ;  the  one  arises  from  the  repulsion  of  their  sur- 
rounding aether,  the  other  from  its  pressure  against  them. 
I  do  not  think,  therefore,  that  anything  has  been  offered  in 
favour  of  the  hypothesis  of  attractive  forces,  so  strong  as  to 
induce  us  to  reject  the  contrary.  I  would  be  understood 
rather  as  waiting  for  more  evidence  previous  to  pledging  my- 
self to  the  adoption  of  either.  The  arguments,  then,  to  which 
I  am  about  to  reply  are  arguments  against  the  law  of  force. 
Those  which  I  have  met  with  are  the  following : — 

1.  That  a  particle  placed  in  a  medium  constituted  of  dis- 
crete molecules  which  exert  actions  varying  according  to  the 
law  of  the  inverse  square  of  the  distance  will  not  vibrate. 

2.  That  the  equilibrium  of  such  a  medium  will  not  be  stable. 

3.  That  the  principal  action  on  a  vibrating  particle  will  be 
due  to  the  remoter  parts  of  the  system ;  and, 

4.  That  the  velocity  of  transmission  will  not  depend  on  the 
length  of  the  wave. 

1.  The  first  argument  is  brought  forward  by  Mr.  Earn- 
shaw  in  a  memoir  "On  the  Nature  of  Molecular  Forces," 
printed  in  the  Transactions  of  the  Cambridge  Philosophical 
Society,  vol.  vii.  p.  97.  The  memoir  is  one  of  great  interest, 
and  the  analytical  equations  are  very  valuable,  but  I  cannot  ad- 
mit the  correctness  of  the  interpretation  which  the  author  has 
assigned  to  them,  in  deducing  "  that  the  molecular  forces 
which  regulate  the  vibrations  of  the  aether  do  not  vary  ac- 
cording to  Newton's  law  of  universal  gravitation." 

The  following  is  an  outline  of  the  argument.  V  is  taken  for 
the  sum  of  each  particle  divided  by  its  distance  from  the  one 
which  is  under  discussion.  The  coordinates  of  any  particle 
m  are  x,  y,  z,  whilst  those  of  the  particle  attracted  are^  g,  h: 
then,   as   Laplace   and   others  have  shown,  the  forces   are 

dV    0  .   ,        ,    .  .    .      .    d2V       d*V       cPV 

—T-jTi  &c.,  and  the  relation  existing  is  -jjv  +  \j  0*  +  ~jT<f 

-  0. 

Now  if  V  =  C,  V  =  C  be  two  values  of  V  for  different 
positions  of  the  same  particle,  it  is  shown  that  2  (C — O) 

=  -j-73  S  /2  -l p-s-  8  £2  +   ? ...    8  h-  is  the  equation  to  a  sur- 

rf/2  J  dg*     b         dk*  ^ 

face,  in  any  point  of  which,  if  the  particle  be  placed,  it  will 


Theory  of  Molecular  Action  according  to  Newton's  Law.  127 
commence  to  move  in  the  direction  of  a  normal.  But  on  ac- 
count  of  the  existing  relation,  the  three  quantities  -^ , 

.  u-,  -tto-j  cannot  all  have  the  same  sign.     The  surface  is 
dgz      an1 

consequently  an  hyperboloid,  and  thus  "  there  are  in  general 
only  three  directions  in  which  a  particle  can  be  displaced,  so 
that  the  force  called  into  play  may  act  in  the  direction  of  the 
displacement."  It  appears  then  that  "  the  constitution  of  a 
medium,  composed  of  detached  attractive  particles,  can  never 
be  such  that  the  force  of  restitution  called  into  play  by  a  dis- 
turbance in  any  direction  shall  act  in  the  line  of  displacement. 
Hence  those  media  which  are  distinguished  as  uncrystallized 
cannot  consist  of  detached  particles  which  either  attract  or  re- 
pel each  other,  with  forces  varying  inversely  as  the  square  of 
the  distance;  because  it  is  assumed  as  a  characteristic  of  such 
media,  that  the  forces  of  restitution  act  always  in  the  direc- 
tion of  displacement."  (Art.  10.) 

To  this  argument  there  are  two  objections: — 

a.  That  the  excepted  case  embodies  the  real  state  of  things  ; 

b.  That  even  were  it  otherwise,  nothing  is  established  against 
the  molecular  theorv. 

d?X  d?V 

dp    -°>    dg* 

•    yi   =  0  is  excepted ;   indeed  the  author  expressly  points 

out  this  circumstance  in  Art.  8.  We  proceed  to  show  that 
this  is  the  very  case  to  be  considered,  in  a  medium  of  sym- 
metry. But  this  phrase  will  perhaps  itself  raise  an  objec- 
tion to  our  arguments.  We  hope  to  be  excused  then  if  we 
make  a  short  digression  hereupon.  A  medium  of  perfect 
symmetry,  it  has  been  argued,  "  has  never  been  shown  to 
exist  in  nature,  nor  is  it  proved  even  that  it  can  exist."  We 
reply  that,  most  assuredly,  a  medium  of  perfect  symmetry 
amongst  detached  particles  cannot  exist  in  nature.  It  is  quite 
inconceivable.  Those  who  have  adopted  it,  have  done  so  "  fo; 
the  sake  of  simplifying  their  equations."  (Earnshaw,  Phil. 
Mag.,  S.  3.  vol.xx.  May  1842,  p.  37Q).  Nor  have  they  regarded 
themselves  as  proceeding  without  reasons  as  valid  and  as  well 
founded  as  those  on  which  any  one  process  in  mathematical 
physics  is  based.  If  it  be  true  from  experiment  that  it  is  per- 
fectly indifferent  in  what  direction  light  passes  through  certain 
media,  then  is  it  of  necessity  equally  true  that  the  sensible 
forces  are  .altogether  uninfluenced  by  direction.  And  more- 
over if  it  is  quite  the  same  thing  whether  motion  takes  place 
from  right  to  left  or  from  left  to  right,  it  is  inconceivable  that 


a.  It  is  evident  that  the  case  in  which -j-^  —  0,     ,  *    =  0, 


128     Prof.  Kelland's  Reply  to  some  Objections  against  the 

forces  which  depend  on  the  excess  of  the  action  due  to  the 
right-hand  direction  above  that  due  to  the  left  can  produce 
any  sensible  effect.  Let  me  repeat  that  it  is  not  geometrical 
symmetry  which  we  assumed ;  a  cubical  arrangement  which 
we  sometimes  speak  of  by  way  of  illustration  is  not  an  arrange- 
ment of  geometric,  symmetry.  But  what  we  do  assume  is  a 
medium  of  mechanical  symmetry;  an  arrangement  of  such  a 
nature  that  all  forces  are  independent  of  direction  either 
throughout  or  on  either  side  of  a  particle.  Perhaps  the  word 
isotropc,  which  M.  Cauchy  uses,  or  isodynamical,  might  ex- 
press the  condition  better  than  the  word  symmetrical,  but 
further  than  the  employment  of  a  term  which  is  incorrect,  and 
of  illustrations  which  are  unsatisfactory,  nothing  can  be  urged 
against  the  introduction  of  the  hypothesis  of  perfect  sym- 
metry. 

d2V 
To  return  to  our  argument.     The  value  of     ,  ^    is 

2(*-/)*-(y-g)*-.(3-a)2      *' 

Zf  m  c  • 

1* 

Now  in  a  medium  of  symmetry 

%m- f-i-  =  2  m  w     *J    =  2  m± r^-. 

d*  V  d*  V  d2  V 

Hence  -™  =  °-     Similarly  -j^-  =  0,  -j^~  =  0. 

Nor  is  it  otherwise  with  an  isotrope  or  isodynamical  medium, 
whatever  be  its  constitution.  In  such  a  medium  the  value  of 
the  square  of  the  velocity  of  transmission  of  a  vibration  de- 
pends on  that  of  the  function 


(r3 


T>       9  X 


3{z-hf\       9  n(y-g) 


c       -       /l         3(z-/*f\ 
or  of      2^^--^-   jsin9 

for  the  velocity  is  independent  of  the  direction  of  vibration. 
The  equality  of  these  two  expressions  gives  us 

(x-ff    .  9*(y—g)        v*   {z-hf    .  a*{y—g) 

Now  this  equality  is  true  whatever  be  the  position  of  the 
vibrating  particle;  that  is,  it  is  perfectly  independent  ofy—g. 
Consequently  the  portions  which  depend  on  each  particular 
value  of  y—  g  must  be  separately  equal  to  one  another.    This 

Cr_n2  (z—hY 

gives  us  2  m  - — j~-  =  £  m  v    ,      .     In  exactly  the  same 

way  does  it  appear  that 

5  m  (£z££  =  5  m  k~g)l.     Hence  -5X  =  0,  &c. 


\jL      V  (L       V  tJL       V  *         * 

established  that  -j-^pt  ■  ,   2   and    ^  7a   are  zero,  in  the  case 


Theory  of  Molecular  Action  according  to  Newton's  Law.  129 

We  have  taken  it  for  granted  that  by  "  a  position  of  equili- 
brium" is  meant  the  place  originally  occupied  by  a  particle 
in  its  state  of  rest.  The  arguments  adduced  by  Mr.  T  irn- 
shaw  evidently  require  that  this  should  be  the  case. 

d?V     d?Y  d2  V  '■ 

Having  shown  that  ■  .  no  ,     .  „  ,  and    T  7C)-  are  all  zero,  it 
°  djz      dg*  dk? 

follows  that  any  argument  based  on  the  express  assumption 

of  the  contrary  is  invalid. 

But  now  it  may  be  urged  that  we  have  only  removed  the 

objection  from  one  point  to  another.     For,  admitting  it  to  be 

d2V     d2V  d2V 

■^ri  -jjf  an(l  ~IW 

in  question,  the  argument  against  the  possibility  of  vibration 
remains  in  full  force.  For  "  the  displacements  of  particles 
placed  in  such  positions  as  those  here  considered  would  not 
bring  into  action  any  forces  of  restitution,  on  which  account 
the  particles  would  not  vibrate."  (Earnshaw,  art.  8.)  This  is 
the  argument.  I  fear  I  do  not  rightly  see  the  connexion 
between  it,  and  the  inference  which  follows :  "  it  is  evident 
therefore  that  the  phaenomena  of  light  and  sound  are  not  due 
to  the  motions  of  particles  placed  in  such  positions."  If  I  am 
wrong  in  conjecturing  the  inference,  I  hope  to  be  set  right ; 
but  so  far  as  I  am  able  to  make  out,  it  is  as  follows  :  a  particle 
is  moved,  its  motion  calls  no  force  into  play  to  draw  it  back, 
therefore  it  will  remain  in  its  new  position,  and  will  not  vi- 
brate. Now  we  reply,  that  before  it  can  be  inferred  that  the 
particle  will  not  vibrate,  it  is  necessary  to  show,  not  only  that 
it  receives  no  instantaneous  action  owing  to  its  change  of  po- 
sition, but  that  it  likewise  exerts  none  on  the  surrounding 
particles.  But  the  latter  requirement  is  assuredly  not  fulfilled. 
The  particles  in  advance  of  that  which  has  been  moved  are 
more  acted  on  than  they  were  before.  Motion  will  therefore 
inevitably  ensue.  This  argument  then  falls  to  the  ground. 
We  have  thus  shown  that  the  objections  are  based  on  a  state 
of  things  different  from  that  which  the  hypothesis  requires ; 
and  that  nothing  which  has  been  said  on  the  contrary  sup- 
position is  available  against  the  theory. 

b.  But  were  it  otherwise,  were  we  to  admit  the  correctness  of 
all  the  reasonings  referred  to — should  we  thereby  be  subject  to 
the  inference  which  has  been  drawn,  "that  a  force,  whether 
attractive  or  repulsive,  varying ,  according  to  Newton's  law, 
cannot  possibly  actuate  the  particles  of  a  vibrating  medium  ?" 
(Earnshaw,  Int.)  By  no  means.  The  inference  rests  on  the 
assumption  that  a  particle  of  the  aether,  when  disturbed,  must 
be  acted  upon  by  forces  in  the  line  of  displacement.     Now 

Phil.  Mag.  S.  3.  Vol.  21.  No.  136.  Aug.  1842.  K 


130     Mr.  C.  Hood  on  Changes  in  the  Structure  of  Iron 

this  assumption  is  never  made  by  writers  on  the  molecular 
hypothesis,  nor  do  I  know  that  it  is  requisite ;  at  least,  before 
we  can  admit  any  argument  based  on  it,  we  require  to  be 
shown  that  it  is  actually  or  virtually  made  in  the  application 
of  the  hypothesis  against  which  the  objection  is  raised.  We 
are  not  aware  that  any  one  has  attempted  to  show  how  vi- 
brations are  generated:  the  question  is  how  they  are  propa- 
gated. Now  in  order  to  the  propagation  of  a  vibration  it  is 
assuredly  requisite  that  the  force  put  in  play  by  a  relative 
series  of  displacements,  should,  on  each  particle,  act  in  the 
line  of  the  displacement.  But  this  force  is  not  a  statical 
force  ;  it  is  due  to  the  actions  of  the  displaced  particles,  and 
dependent  altogether  on  their  displacement ;  in  a  medium  of 
symmetry,  and  on  the  Newtonian  law.  (See  my  Memoir, 
Trans.  Camb.  Phil.  Soc.  vii.  p.  244.)  The  whole  line  of 
argument,  therefore,  is  inadmissible.  No  objection  based  on 
the  want  of  fulfilment  of  the  conditions  of  vibration  can  be 
valued,  unless  it  distinctly  recognises  all  those  conditions. 

P.S.  Since  writing  the  above,  Professor  Braschmann  of 
Moscow  has  favoured  me  with  a  sight  of  his  "  Theory  of 
Equilibrium,"  which  contains  M.  Mossotti's  views.  It  is 
written  in  Russ,  but  as  the  author  promises  me  a  copy  of 
the  work  with  manuscript  translations  of  some  of  the  more 
important  passages,  I  hope  in  a  future  communication  to  pro- 
fit by  it. 

XXII.   On  some  peculiar  Changes  in  the  Internal  Structure  of 
Iron,  independent  of,  and  subsequent  to,   the  several  Pro- 
cesses of  its  Manufacture.      By  Charles  Hood,    Esq., 
F.R.A.S.,  $c*. 
nPHE  important  purposes  to  which  iron  is  applied  have  al- 
-*■      ways  rendered  it  a  subject  of  peculiar  interest ;  and  at 
no  period  has  its  importance  been  so  general  and  extensive 
as  at  the  present  time,  when  its  application  is  almost  daily  ex- 
tending, and  there  is  scarcely  anything  connected  with  the 
arts,  to  which,  either  directly  or  indirectly,  it  does  not  in  some 
degree  contribute.      My  object  in  the  present  paper  is  to 
point  out  some  peculiarities  in  the  habitudes  of  iron,  which 
appear  almost  wholly  to  have  escaped  the  attention  of  scien- 
tific men;  and  which,  although  in  some  degree  known  to 
practical  mechanics,  have  been  generally  considered  by  them 
as  isolated  facts,  and  not  regarded  as  the  results  of  a  general 
and  important  law.     The  circumstances,  however,  well  de- 
serve the  serious  attention  of  scientific  men,  on  account  of  the 
very  important  consequences  to  which  they  lead. 

*  Communicated  by  the  Author :  having  been  read  before  the  Institu- 
tion of  Civil  Engineers,  June  21,  1842. 


subsequent  to  its  Manufacture.  131 

The  two  great  distinctions  which  exist  in  malleable  wrought 
iron,  are  known  by  the  names  of  "  red  short "  and  tf  cold 
short "  qualities.  The  former  of  these  comprises  the  tough 
fibrous  iron,  which  generally  possesses  considerable  strength 
when  cold ;  the  latter  shows  a  bright  crystallized  fracture, 
and  is  very  brittle  when  cold,  but  works  ductile  while  hot. 
These  distinctions  are  perfectly  well  known  to  all  those  who 
are  conversant  with  the  qualities  of  iron  :  but  it  is  not  gene- 
rally known  that  there  are  several  ways  by  which  the  tough 
red  shot  iron  becomes  rapidly  converted  into  the  crystallized, 
and  by  this  change  its  strength  is  diminished  to  a  very  great 
extent. 

The  importance  which  attaches  to  this  subject  at  the  pre- 
sent time  will  not,  I  think,  be  denied.  The  recent  accident 
on  the  Paris  and  Versailles  Railway,  by  which  such  a  lament- 
able sacrifice  of  human  life  has  occurred,  arose  from  the  break- 
ing of  the  axle  of  a  locomotive  engine,  and  which  axle  pre- 
sented at  the  fractured  parts  the  appearance  of  the  large 
crystals  which  always  indicate  cold  short  and  brittle  iron.  I 
believe  there  is  no  doubt,  however,  that  this  axle,  although 
presenting  such  decided  evidence  of  being  at  the  time  of  this 
accident  of  the  brittle  cold  short  quality,  was  at  no  distant 
period  tough  and  fibrous  in  the  highest  degree;  and  as  the 
French  Government  have  deemed  the  matter  of  sufficient  im- 
portance to  be  inquired  into  by  a  special  commission,  I  trust 
that  some  remarks  on  the  subject  will  be  interesting  to  the 
members  of  the  Institution  of  Civil  Eugineers.  I  propose, 
therefore,  to  show  how  these  extraordinary  and  most  import- 
ant changes  occur,  and  shall  point  out  some  at  least  of  the 
modes  by  which  we  can  demonstrate  the  truth  of  this  asser- 
tion by  actual  experiment. 

The  principal  causes  which  produce  this  change,  are  per- 
cussion, heat,  and  magnetism  :  and  it  is  doubtful  whether 
either  of  these  means  per  se  will  produce  this  effect;  and  there 
appear  strong  reasons  for  supposing  that  generally  they  are 
all  in  some  degree  concerned  in  the  production  of  the  ob- 
served results. 

The  most  common  exemplification  of  the  effect  of  heat  in 
crystallizing  fibrous  iron,  is  by  breaking  a  wrought-iron  furnace 
bar,  which,  whatever  quality  it  was  of  in  the  first  instance, 
will  in  a  short  time  invariably  be  converted  into  crystallized 
iron :  and  by  heating  and  rapidly  cooling,  by  quenching  with 
water  a  few  times,  any  piece  of  wrought  iron,  the  same  effect 
may  be  far  more  speedily  produced. 

In  these  cases  we  have  at  least  two  of  the  above  causes  in 
operation, — heat  and  magnetism.     In  every  instance  of  heat- 

K2 


132     Mr.  C.  Hood  on  Changes  in  the  Structure  of  Iron 

ing  iron  to  a  very  high  temperature,  it  undergoes  a  change  in 
its  electric  or  magnetic  condition ;  for  at  very  high  tempe- 
ratures iron  entirely  loses  its  magnetic  powers,  which  return 
as  it  gradually  cools  to  a  lower  temperature.  In  the  case  of 
quenching  the  heated  iron  with  water,  we  have  a  still  more 
decisive  assistance  from  the  electric  and  magnetic  forces ;  for 
Sir  Humphry  Davy  long  since  pointed  out*  that  all  cases  of 
vaporization  produced  negative  electricity  in  the  bodies  in 
contact  with  the  vapour ;  a  fact  which  has  lately  excited  a 
good  deal  of  attention,  in  consequence  of  the  discovery  of 
large  quantities  of  negative  electricity  in  effluent  steam. 

These  results,  however,  are  practically  of  but  little  conse- 
quence ;  but  the  effects  of  percussion  are  at  once  various,  ex- 
tensive, and  of  high  importance.  We  shall  trace  these  effects 
under  several  different  circumstances. 

In  the  manufacture  of  some  descriptions  of  hammered  iron, 
the  bar  is  first  rolled  into  shape,  and  then  one  half  the  length 
of  the  bar  is  heated  in  a  furnace  and  immediately  taken  to 
the  tilt-hammer  and  hammered  ;  and  the  other  end  of  the  bar 
is  then  heated  and  hammered  in  the  same  manner.  In  order 
to  avoid  any  unevenness  in  the  bar,  or  any  difference  in  its 
colour,  where  the  two  distinct  operations  have  terminated,  the 
workman  frequently  gives  the  bar  a  few  blows  with  the  ham- 
mer on  that  part  which  he  first  operated  upon.  That  part  of 
the  bar  has,  however,  by  this  time  become  comparatively 
cold ;  and  if  this  cooling  process  has  proceeded  too  far  when 
it  receives  this  additional  hammering,  that  part  of  the  bar  im- 
mediately becomes  crystallized,  and  so  extremely  brittle  that 
it  will  break  to  pieces  by  merely  throwing  it  on  the  ground, 
though  all  the  rest  of  the  bar  will  exhibit  the  best  and  toughest 
quality  imaginable.  This  change,  therefore,  has  been  pro- 
duced by  percussion  (as  the  primary  agent),  when  the  bar  is 
at  a  lower  temperature  than  a  welding  heat. 

We  here  see  the  effects  of  percussion  in  a  very  instructive 
form.  And  it  must  be  observed  that  it  is  not  the  excess  of 
hammering  which  pi'oduces  the  effect,  but  the  absence  of  a 
sufficient  degree  of  heat  at  the  time  the  hammering  takes 
place ;  and  the  evil  may  probably  be  all  produced  by  four  or 
five  blows  of  the  hammer,  if  the  bar  happens  to  be  of  a  small 
size.  In  this  case  we  witness  the  combined  effects  of  percus- 
sion, heat,  and  magnetism.  When  the  bar  is  hammered  at 
the  proper  temperature  no  such  crystallization  takes  place, 
because  the  bar  is  insensible  to  magnetism.  But  as  soon  as 
the  bar  becomes  of  that  lower  degree  of  temperature  at  which 
it  can  be  affected  by  magnetism,  the  effect  of  the  blows  it  re- 
*  Davy's  Chemical  Philosophy,  p.  138. 


subsequent  to  its  Manufacture.  133 

ceives  is  to  produce  magnetic  induction,  and  that  magnetic 
induction  and  consequent  polarity  of  its  particles,  when  as- 
sisted by  further  vibrations  from  additional  percussion,  pro- 
duces a  crystallized  texture.  For  it  is  perfectly  well  known 
that  in  soft  iron  magnetism  can  be  almost  instantaneously  pro- 
duced by  percussion ;  and  it  is  probable  that  the  higher  the 
temperature  of  the  bar  at  the  time  it  receives  the  magnetism, 
the  more  likely  will  it  be  to  allow  of  that  re-arrangement  of 
its  molecules  which  would  constitute  the  crystallization  of  the 
iron. 

It  is  not  difficult  to  produce  the  same  effects  by  repeated 
blows  from  a  hand-hammer  on  small  bars  of  iron ;  but  it  ap- 
pears to  depend  upon  something  peculiar  in  the  blow,  which 
to  produce  the  effect  must  occasion  a  complete  vibration 
among  the  particles  in  the  neighbourhood  of  the  part  which 
is  struck.  And  it  is  remarkable  that  the  effects  of  the  blows 
in  all  cases  seem  to  be  confined  within  certain  limited  di- 
stances of  the  spot  which  receives  the  strokes.  Mr.  Charles 
Manby  has  mentioned  to  me  a  circumstance  which  fully  bears 
out  this  statement.  In  the  machine  used  for  blowing  air  at 
the  Beaufort  Iron  Works,  the  piston-rod  of  the  blowing  cy- 
linder, for  a  considerable  time,  had  a  very  disagreeable  jar  in 
its  motion,  the  cause  of  which  could  not  be  discovered.  At 
last  the  piston-rod  broke  off  quite  short,  and  close  to  the 
piston ;  and  it  was  then  discovered  that  the  key  had  not  pro- 
perly fastened  the  piston  and  the  rod  together.  The  rod  at 
the  fracture  presented  a  very  crystallized  texture ;  and  as  it 
was  known  to  have  been  made  from  the  very  best  iron,  it  ex- 
cited considerable  surprise.  The  rod  was  then  cut  at  a  short 
distance  from  the  fracture,  and  it  was  found  to  be  tough  and 
fibrous  in  a  very  high  degree ;  showing  what  I  have  already 
pointed  out,  that  the  effects  of  percussion  generally  extend 
only  a  very  short  distance.  In  fact,  we  might  naturally  ex- 
pect, that  as  the  effect  of  vibration  diminishes  in  proportion 
to  the  distance  from  the  stroke  which  produces  it,  so  the  cry- 
stallization, if  produced  by  this  means,  would  also  diminish 
in  the  same  proportion.  The  effect  of  magnetism  alone  may 
also  be  estimated  from  this  circumstance.  The  rod  would  of 
course  be  magnetic  throughout  its  whole  length ;  this  being 
a  necessary  consequence  of  its  position,  independent  of  other 
circumstances;  but  the  necessary  force  of  vibration  among 
its  particles  only  extended  for  a  short  distance,  and  to  that 
extent  only  did  the  crystallization  proceed.  The  effect  of 
magnetism  in  assisting  the  crystallization,  I  think  it  unneces- 
sary to  dwell  upon,  as  the  extensive  use  of  galvanic  currents 
in  modern  times  has  fully  proved  their  power  in  crystallizing 


1S4     Mr.  C.  Hood  on  Changes  in  the  Structure  of  Iron 

some  of  the  most  refractory  substances ;  but  by  themselves 
they  are  unable  to  produce  these  effects  on  iron»  or  at  least 
the  operation  must  be  extremely  slow. 

Another  circumstance  which  occurred  under  Mr.  Manby's 
observation,  confirms  generally  the  preceding  opinions,  A 
small  bar  of  good  tough  iron  was  suspended  and  struck  con- 
tinuously with  small  hand-hammers,  to  keep  up  a  constant 
vibration.  The  bar,  after  the  experiment  had  been  continued 
for  some  considerable  time,  became  so  extremely  brittle,  that 
it  entirely  fell  to  pieces  under  the  light  blows  of  the  hand- 
hammers,  presenting  throughout  its  structure  a  highly  cry- 
stallized appearance. 

The  fracture  of  the  axles  of  road  vehicles  of  all  kinds  is 
another  instance  of  the  same  kind.  I  have  at  different  times 
examined  many  broken  axles  of  common  road  vehicles,  and 
I  never  met  with  one  which  did  not  present  a  crystallized 
fracture,  while  it  is  almost  certain  that  this  could  not  have 
been  the  original  character  of  the  iron,  as  they  have  fre- 
quently been  used  for  years  with  much  heavier  loads,  and  at 
last  have  broken  without  any  apparent  cause,  with  lighter 
burdens  and  less  strain  than  they  have  formerly  borne.  The 
effects,  however,  on  the  axles  of  road  vehicles  are  generally 
extremely  slow,  arising,  I  apprehend,  from  the  fact  that,  al- 
though they  receive  a  great  amount  of  vibration,  they  possess 
a  very  small  amount  of  magnetism,  and  are  not  subject  to  a 
high  temperature.  The  degree  of  magnetism  they  receive 
must  be  extremely  small,  from  their  position  and  their  con- 
stant change  with  regard  to  the  magnetic  meridian  the  abs- 
ence of  rotation,  and  their  insulation  by  the  wood  spokes  of 
the  wheels.  Whether  the  effects  are  equally  slow  with  iron 
wheels  used  on  common  roads,  may  perhaps  admit  of  some 
question. 

With  railway  axles,  however,  the  case  is  very  different. 
In  every  instance  of  a  fractured  railway  axle,  the  iron  has 
presented  the  same  crystallized  appearance ;  but  this  effect, 
I  think,  we  shall  find  is  likely  to  be  produced  far  more  ra- 
pidly than  we  might  at  first  expect,  as  these  axles  are  subject 
to  other  influences,  which,  if  the  theory  here  stated  be  correct, 
must  greatly  diminish  the  time  required  to  produce  the  change 
in  some  other  cases.  Unlike  other  axles,  those  used  on  rail- 
ways rotate  with  the  wheels,  and  consequently  must  become 
during  their  rotation  highly  magnetic.  Messrs.  Barlow  and 
Christie  were  the  first  to  demonstrate  the  magnetism  by  ro- 
tation produced  in  iron,  which  was  afterwards  extended  by 
Messrs.  Herschel  and  Babbage  to  other  metals  generally,  in 
verifying  some  experiments  by  M.  Arago.    It  cannot,  I  think, 


subsequent  to  its  Manufacture.  13$ 

be  doubted,  that  all  railway  axles  become  from  this  cause 
highly  magnetic  during  the  time  they  are  in  motion,  though 
they  may  not  retain  the  magnetism  permanently.  But  in  the 
axles  of  locomotive  engines  we  have  yet  another  cause  which 
may  tend  to  increase  the  effect.  The  vaporization  of  water 
and  the  effluence  of  steam  have  already  been  stated  to  produce 
large  quantities  of  negative  electricity  in  the  bodies  in  con- 
tact with  the  vapour;  and  Dr.  Ure  has  shown*  that  negative 
electricity,  in  all  ordinary  cases  of  crystallization,  instantly 
determines  the  crystalline  arrangement.  This  of  course  must 
affect  a  body  of  iron  in  a  different  degree  to  that  of  ordinary 
cases  of  crystallization ;  but  still  we  see  that  the  effects  of 
these  various  causes  all  tend  in  one  direction,  producing  a 
more  rapid  change  in  the  internal  structure  of  the  iron  of  the 
axle  of  a  locomotive  engine,  than  occurs  in  almost  any  other 
case. 

Dr.  Wollaston  first  pointed  out  that  the  forms  in  which 
native  iron  is  disposed  to  break,  are  those  of  the  regular  oc- 
tahedron and  tetrahedron,  or  rhomboid,  consisting  of  these 
forms  combined.  The  tough  and  fibrous  character  of  wrought 
iron  is  entirely  produced  by  art ;  and  we  see  in  these  changes 
that  have  been  described,  an  effort  at  returning  to  the  natural 
and  primal  form ;  the  crystalline  structure,  in  fact,  being  the 
natural  state  of  a  large  number  of  the  metals ;  and  Sir  Hum- 
phry Davy  has  shown  that  all  those  which  are  fusible  by  or- 
dinary means  assume  the  form  of  regular  crystals  by  slow 
cooling. 

The  general  conclusion  to  which  these  remarks  lead  us, 
appears,  I  think,  to  leave  no  doubt  that  there  is  a  constant 
tendency  in  wrought-iron,  under  certain  circumstances,  to  re- 
turn to  the  crystallized  state;  but  that  this  crystallization  is 
not  necessarily  dependent  upon  time  for  its  development,  but 
is  determined  solely  by  other  circumstances,  of  which  the 
principal  is  undoubtedly  vibration.  Heat,  within  certain  li- 
mits, though  greatly  assisting  the  rapidity  of  the  change,  is 
certainly  not  essential  to  it;  but  magnetism,  induced  either 
by  percussion  or  otherwise,  is  an  essential  accompaniment  of 
the  phenomena  attending  the  change. 

At  a  recent  sitting  of  the  Academy  of  Sciences  at  Paris, 
M.  Bosquillon  made  some  remarks  relative  to  the  causes  of 
the  breaking  of  the  axle  on  the  Versailles  Railroad ;  and  he 
appears  to  consider  that  this  crystallization  was  the  joint  ef- 
fect of  time  and  vibration,  or  rather,  that  this  change  only 
occurs  after  a  certain  period  of  time.  From  what  has  here 
been  said,  it  will  be  apparent  that  a  fixed  duration  of  time  is 

*  Journal  of  Science,  vol.  v.  p.  106. 


136     Mr.  C..Hood  on  Changes  in  the  Structure  of  Iron. 

not  an  essential  element  in  the  operation ;  that  the  change, 
under  certain  circumstances,  may  take  place  instantaneously ; 
and  that  an  axle  may  become  crystallized  in  an  extremely 
short  period  of  time,  provided  that  vibrations  of  sufficient 
force  and  magnitude  be  communicated  to  it.  This  circum- 
stance would  point  out  the  necessity  for  preventing  as  much 
as  possible  all  jar  and  percussion  on  railway  axles.  No 
doubt  one  of  the  great  faults  of  both  engines  and  carriages 
of  every  description — but  particularly  the  latter — is  their  pos- 
sessing far  too  much  rigidity;  thus  increasing  the  force  of 
every  blow  produced  by  the  numerous  causes  incidental  to 
railway  transit;  by  causing  the  whole  weight  of  the  entire 
body  in  motion  to  act  by  its  momentum  in  consequence  of  the 
perfect  rigidity  of  the  several  parts  and  the  manner  of  their 
connection  with  each  other,  instead  of  such  a  degree  of  elas- 
ticity as  would  render  the  different  parts  nearly  independent 
of  one  another,  in  the  case  of  sudden  jerks  or  blows ;  and  which 
rigidity  must  produce  very  great  mischief,  both  to  the  road 
and  to  the  machinery  moving  upon  it.  The  looseness  of  the 
axles  in  their  brasses  must  also  be  another  cause  which  would 
greatly  increase  this  evil. 

Although  I  have  more  particularly  alluded  to  the  change 
in  the  internal  structure  of  iron  with  reference  to  the  effects 
on  railway  axles,  it  need  scarcely  be  observed  that  the  same 
remarks  would  apply  to  a  vast  number  of  other  cases,  where 
iron,  from  being  more  or  less  exposed  to  similar  causes  of  ac- 
tion, must  be  similarly  acted  upon.  The  case  of  railway  axles 
appears  to  be  of  peculiar  and  pressing  importance,  well  de- 
serving the  most  serious  consideration  of  scientific  men,  and 
particularly  deserving  the  attention  of  those  connected  with 
railways,  or  otherwise  engaged  in  the  manufacture  of  railway 
machinery,  who  have  the  means  of  testing  the  accuracy  of  the 
theory  here  proposed.  For  if  the  \iews  I  have  stated  be 
found  to  harmonize  with  the  deductions  of  science,  and  to  co- 
incide with  the  results  of  experience,  they  may  have  a  very 
important  effect  upon  public  safety.  It  may  be  observed,  on 
the  other  hand,  however,  that  at  the  present  time  all  railway 
axles  are  made  infinitely  stronger  than  would  be  necessary  for 
resisting  any  force  they  would  have  to  sustain  in  producing 
fracture,  provided  the  iron  were  of  the  best  quality ;  and  to 
this  circumstance  may  perhaps  be  attributed  the  comparative 
freedom  from  serious  accidents  by  broken  axles.  The  neces- 
sity for  resisting  flexure  and  the  effects  of  torsion,  are  reasons 
why  railway  axles  never  can  be  made  of  such  dimensions  only 
as  would  resist  simple  fracture ;  but  it  would  be  very  desi- 
rable to  possess  some  accurate  experiments  on  the  strength  of 


Prof.  Lloyd  on  the  Magnetic  Disturbance  of  July  2  #4",  184-2.   137 

wrought  iron  in  different  stages  of  its  crystallization,  as  there 
can  be  no  doubt  that  very  great  differences  exist  in  this  re- 
spect, and  it  is  probable  that  in  most  cases,  when  the  crystal- 
lization has  once  commenced,  the  continuance  of  the  same 
causes  which  first  produced  it  goes  on  continually  increasing 
it,  and  thereby  further  reduces  the  cohesive  strength  of  the 
iron. 
Earl  Street,  May  31,  1842. 

[Several  samples  of  broken  railway  axles  accompanied  this 
paper,  and  were  exhibited  at  the  Meeting.  In  some  of  them 
the  same  axle  was  broken  in  different  places,  and  showed  that 
where  the  greatest  amount  of  percussion  had  been  received, 
the  crystallization  of  the  iron  was  far  more  extensive  than  in 
those  parts  where  the  percussion  had  been  less.] 

XXIII.  Notice  of  a  remarkable  Magnetic  Disturbance  which 
occurred  on  the  2nd  and  Mh  of  July,  184-2.  By  the  Rev. 
Humphrey  Lloyd,  D.D.,  F.R.S.,  V.P.R.I.A.,  Professor 
of  Natural  Philosophy  in  the  University  of  Dublin. 

To  Richard  Taylor,  Esq. 
Dear  Sir, 

A  VERY  remarkable  magnetic  disturbance  (the  most  re- 
■^*-  mar/cable  I  ever  witnessed)  occurred  in  the  beginning  of 
the  present  month.  A  brief  ske*tch  of  some  of  the  principal 
features  of  the  phenomenon,  as  they  were  observed  at  the 
Dublin  Magnetical  Observatory,  may  probably  interest  some 
of  your  readers. 

On  the  2nd  of  July,  at  6  a.m.  (Gottingen  mean  time),  the 
attention  of  one  of  the  assistant  observers  (Mr.  O'Neill)  was 
arrested  by  the  extraordinary  deviation  of  all  the  magnets  from 
their  mean  positions,  accompanied  by  a  large  vibration;  and 
he  immediately  commenced  a  series  of  observations  at  short 
intervals.  The  disturbance  of  the  declination  (by  which  I  mean 
the  deviation  of  the  freely  suspended  horizontal  magnet  from 
the  mean  place  corresponding  to  that  horn-)  then  amounted  to 
149*2  divisions  of  the  scale  of  the  instrument,  or  1°  47'#3  of  arc, 
— the  north  end  of  the  magnet  deviating  towards  the  west,  or 
the  declination  increased.  The  magnet  of  the  bifilar  magneto- 
meter  was  driven  beyond  the  limits  of  the  scale  of  its  colli- 
mator ;  and  the  diminution  of  the  horizontal  intensity  exceeded 
the  jpth  of  the  whole  force.  Both  magnets  were  returning 
rapidly  towards  their  mean  positions  at  the  moment  of  the 
first  observation ;  so  that  the  epoch  of  the  greatest  change  was 
before  6  a.m.,  and  its  amount  exceeded  that  observed.     The 


138      Prof.  Lloyd's  Notice  of  a  Magnetic  Disturbance 

observations  taken  at  the  regular  hours  immediately  prece- 
ding (2  and  4  a.m.  Gotfingen  mean  time)  gave  no  warning  of 
the  approaching  change. 

From  6  a.m.,  for  nearly  an  hour,  both  magnets  returned 
rapidly,  and  almost  uninterruptedly,  towards  their  mean  posi- 
tions, the  declination  diminishing,  and  the  horizontal  intensity 
increasing.  The  latter  element  reached  its  maximum  at  6h 
56m;  the  declination  continued  to  decrease  until  7h  12m.  After 
this,  no  very  marked  change  occurred  for  some  time,  and  the 
extra  observations  were  discontinued  at  8h  36m. 

At  10  a.m.  the  declinometer  indicated  an  increase  of  de- 
clination amounting  to  18*6  minutes;  and  the  extra  observa- 
tions were  resumed,  and  continued  for  an  hour.  By  this  time 
(11  a.m.)  both  instruments  had  attained  nearly  their  mean 
positions,  from  which  the  observations  taken  at  the  regular 
magnetic  hours  next  following  (noon,  2  p.m.  4  p.m.)  showed 
no  variation. 

The  extra  observations  were  resumed  at  5h  36m  p.m.,  the 
bifilar  magnetometer  then  indicating  an  increase  of  the  hori- 
zontal intensity,  amounting  to  "0062  of  the  whole.  The  ob- 
servations were  continued  for  more  than  an  hour,  but  with- 
out the  occurrence  of  any  very  marked  change. 

The  regular  observation  at  10  p.m.  showed  a  considerable 
decrease  of  declination,  accompanied  by  a  decrease  of  hori- 
zontal intensity ;  and  at  1 1  p.m.  the  extra  observations  were 
resumed,  and  continued,  with  both  instruments  simultaneously, 
until  Sunday  morning.  In  this  interval  another  very  remark- 
able change  took  place.  The  declination,  after  some  irre- 
gular oscillations,  began  to  increase  rapidly,  and  reached  its 
maximum  at  llh48m,  the  deviation  from  its  mean  value  being 
then  28*1  minutes.  It  then  returned  with  a  very  rapid  move- 
ment, and  in  eight  minutes  the  magnet  traversed  83  divisions 
of  the  scale,  or  1°  of  arc;  after  which  it  made  some  smaller 
oscillations  of  the  same  rapid  kind.  The  change  of  the  hori- 
zontal intensity  which  occurred  at  the  same  time  was  still  more 
remarkable.  This  element  increased  from  1  lh  8m  to  1 11*  20m ; 
it  then  rapidly  diminished  for  12  minutes  more;  in  another 
6  minutes  it  reached  a  second  maximum  (at  llh  38m);  and 
finally  the  magnet  was  driven  impetuously  beyond  the  limits 
of  the  scale  in  the  opposite  direction,  the  intensity  reaching  its 
minimum  at  llh  50m,  and  the  disturbance  exceeding  the  j^th 
of  the  whole  intensity.  The  returning  oscillation  occupied 
12  minutes  more;  and  at  12h  2m  the  magnet  returned  to  its 
extreme  position  on  the  opposite  side,  the  fluctuation  in  this 
time  exceeding  111  divisions  of  the  scale.  The  disturbance 
during  these  two  hours  was  characterized  by  the  absence  of  all 


Which  occurred  on  the  2nd  and  Uh  of  July,  1842,     139 

vibratory  movement,  notwithstanding  the  magnitude  of  the 
changes. 

There  seemed  to  be  a  faint  auroral  light  in  the  N.W.  hori- 
zon, but  without  streamers. 

When  the  regular  observations  were  recommenced,  on 
Monday  the  4-th  instant,  the  disturbing  forces  were  found  to 
be  still  in  activity.  At  2  and  4  a.m.  the  instruments  showed 
a  very  considerable  decrease  of  declination,  accompanied  by  a 
great  decrease  of  horizontal  intensity.  At  6  a.m.  the  declina- 
tion exceeded  the  mean  of  the  hour  by  a  still  greater  amount  j 
and  the  horizontal  intensity  had  also  increased,  though  still  be- 
low its  mean  value.  All  the  magnets  were  then  vibrating 
through  very  large  arcs.  The  series  of  observations  at  short 
intervals  was  then  begun,  and  continued  (almost  without  in- 
terruption) for  ten  hours. 

At  6h  24ra  the  declination  reached  its  maximum,  the  devia- 
tion then  amounting  to  43'2  minutes.  The  horizontal  inten- 
sity also  attained  its  maximum  very  nearly  at  the  same  mo- 
ment. The  two  elements  then  began  to  diminish  rapidly  and 
simultaneously;  and  between  7  and  8  a.m.  there  was  a  double 
minimum  of  both,  separated  by  an  intervening  maximum, 
that  of  the  horizontal  intensity  taking  place  a  few  minutes 
earlier  than  the  other  element. 

At  9  a.m.  the  disturbance  was  extremely  rapid.  The  mag- 
nets were  hurried  to  and  fro  with  a  violent  movement;  and 
these  changes  of  mean  position  were  accompanied  by  a  large 
vibration,  amounting  in  some  instances  (notwithstanding  the 
copper  rings)  to  20  divisions  of  the  scale. 

This  combination  of  movements  rendered  it  difficult  to  seize 
the  moment  of  greatest  deviation,  or  to  determine  its  precise 
amount.  The  declination  attained  a  minimum  at  9  a.m., 
which  was  followed  by  a  marked  maximum  at  91*  22m,  the 
range  of  the  oscillation  being  29*4  minutes.  There  was  a 
corresponding  change  of  the  intensity,  but  somewhat  later  in 
time, — the  minimum  occurring  at  9h  14m,  and  the  maximum 
at  9*1  50m;  and  the  range  amounting  to  *0147» 

The  changes  of  declination  which  occurred  afterwards  did 
not  present  any  remarkable  features ;  but  the  horizontal  in- 
tensity, which  was  previously  less  than  in  its  mean  state,  after 
reaching  a  minimum  at  lh  44m,  suddenly  increased  to  an 
amount  exceeding  its  mean  value,  and  reached  a  maximum 
at  2h  5m  p.m.  The  period  of  this  maximum  was  characterized 
by  a  sudden  increase  of  the  arc  of  vibration,  as  if  by  impulse. 
The  intensity  continued  above  its  mean  value  (though  with 
some  considerable  oscillations)  during  the  remainder  of  the 
time  of  observation.     The  disturbance  ceased  about  5  p.m. 

The  induction  inclinometer  was  observed,  in  conjunction 


140  Prof.  Lloyd  on  the  Magnetic  Disturbance  of  July  2  Sf^  1842. 

with  the  other  two  instruments ;  but  the  observations  are  un- 
reduced, and  I  am  therefore  unprepared  as  yet  to  offer  any 
remark  respecting  the  changes  of  inclination  or  total  intensity. 
It  is  manifest,  however,  even  from  this  imperfect  sketch,  that 
this  disturbance  presents  many  features  of  prominent  interest: 

1.  In  the  great  magnitude,  and  marked  and  abrupt  cha- 
racter of  the  principal  changes.  In  both  these  respects  the 
changes  at  6  a.m.  and  12  p.m.  on  the  2nd  instant,  afford  per- 
haps the  most  interesting  points  of  comparison  of  any  that  the 
system  of  simultaneous  observation  has  yet  furnished ;  and 
much  light  may  be  expected  to  be  thrown  on  the  phaenomena 
by  a  comparison  of  the  results  which  may  certainly  be  ex- 
pected to  arrive  from  the  colonial  observatories,  as  well  as  of 
those  which  have  been  probably  obtained  at  Port  Louis,  in 
the  moveable  observations  of  the  Antarctic  expedition. 

2.  In  the  striking  confirmation  which  it  affords  to  the  con- 
clusion of  Prof.  Kreil,  viz.  that  all  the  greater  changes  are 
accompanied  by  a  diminution  in  the  horizontal  component  of 
the  intensity.  The  whole  of  the  day  following  the  disturbance 
(July  5)  was  also  characterized  by  a  diminished  intensity, 
which  is  also  in  accordance  with  the  inductions  of  Prof.  Kreil; 
but  the  increase  of  this  element  towards  the  close  of  the  dis- 
turbance (in  the  afternoon  of  the  4th)  is  in  opposition  to  one 
of  his  conclusions. 

3.  In  the  two  classes  of  changes  exhibited;  in  one  of  which 
(as  on  the  evening  of  the  2nd)  the  disturbances  from  the  mean 
position,  although  great  and  rapid,  were  accomplished  with- 
out any  sensible  vibration  of  the  magnets ;  while  in  the  other 
(as  on  the  morning  of  the  4th)  the  vibration  exceeded  any 
ever  witnessed  in  this  observatory,  since  the  application  of 
the  copper  rings. 

4.  In  the  occurrence  of  great  magnetic  changes  without 
any  marked  auroral  phaenomena.  The  sky  was  clear  on  the 
night  of  the  2nd,  during  a  very  remarkable  part  of  the  dis- 
turbance, and  a  light  was  seen  in  the  N.W., — but  of  a  very 
uncertain  nature,  and  without  any  of  the  distinguishing  cha- 
racters of  the  aurora.  I  may  observe,  however,  that  through- 
out the  whole  of  the  3rd,  and  the  greater  part  of  the  4th,  the 
sky  was  covered  during  the  day  with  a  peculiar  milky  white- 
ness, apparently  belonging  to  something  distinct  from  and 
above  the  clouds ;  and  that  this  disappeared  suddenly,  and 
the  blue  sky  became  visible,  about  5  p.m.  on  the  4th,  when 
the  disturbance  was  at  an  end.  I  could  not  help  regarding  this 
appearance  as  connected  with  aurora. 

Believe  me,  dear  Sir,  faithfully  yours, 
Trinity  College,  Dublin,  H.  Lloyd. 

July  19, 1842. 


[  141  ] 

XXIV.  Proceedings  of  Learned  Societies. 

GEOLOGICAL  SOCIETY. 
[Continued  from  vol.  xx.  p.  594.] 

Nov.  3,  A  MEMOIR  entitled  "  Supplement  to  a  •  Synopsis  of  the 
1841.  -^*-  English  Series  of  Stratified  Rocks  inferior  to  the  Old 
Red  Sandstone/  with  Additional  Remarks  on  the  Relations  of  the 
Carboniferous  Series  and  Old  Red  Sandstone  of  the  British  Isles," 
hy  the  Rev.  Adam  Sedgwick,  F.G.S.,  Woodwardian  Professor  in  the 
University  of  Cambridge,  was  begun. 

Nov.  1 7 . — Professor  Sedgwick's  paper,  commenced  at  the  preceding 
meeting,  was  concluded. 

The  author  states  that  his  former  synopsis*  is  now  modified ;  1st, 
by  the  new  classification  of  the  stratified  rocks  of  Devon  and  Corn- 
wall {Devonian  system)  ;  2ndly,  by  a  larger  knowledge  of  fossils  de- 
rived from  some  of  the  groups  described ;  3rdly,  by  new  observations 
made  during  the  past  summer  in  the  south  of  Ireland,  the  south- 
western parts  of  Scotland,  and  in  the  north  of  England. 

New  Red  Sandstone. — 1.  England. — It  is  shown,  by  sections  de- 
rived from  Warwickshire,  that  the  upper  part  of  the  new  red  sandstone 
is  sometimes  unconformable  to  the  lower  part,  which  represents  the 
magnesian  limestone  and  lowest  division  of  the  new  red  sandstone 
group.  It  is  also  shown  that  the  coal-measures  pass  into  the  overlying 
new  red  sandstone  series  through  the  intervention  of  bands  of  red  marl 
alternating  with  two  bands  of  freshwater  limestone,  the  whole  beds 
of  passage  being  loaded  with  common  coal-plants.  The  author  then 
discusses  the  sections  near  Whitehaven.  They  show  no  passage 
from  the  lower  new  red  sandstone  (rotheliegende)  to  the  coal-mea- 
sures ;  but  they  show  that  the  flora  of  the  coal-field  existed  appa- 
rently in  full  perfection  during  the  period  of  the  lower  new  red  sand- 
stone :  of  this  flora  he  has  obtained  many  new  specimens.  He  states 
that  the  additional  facts  lend  support  to  the  suggestion  thrown  out 
by  Mr.  Murchison  and  himself  respecting  the  age  of  the  coal-field 
on  the  flanks  of  the  Hartz. 

2.  Scotland. — The  new  red  sandstone  of  Dumfries- shire  is  continu- 
ous with  that  of  the  plains  of  Carlisle,  and  is  seen  overlying  the  coal- 
measures  from  the  valley  of  the  Esk,  near  Canobie,  to  the  neighbour 
hood  of  Dumfries.  Near  the  latter  place  it  is  in  mineral  structure 
the  same  with  the  red  sandstone  of  Corncockle-moor,  and,  at  both 
places,  the  red  flags  contain  impressions  of  footsteps.  The  author 
therefore  asserts  that  the  red  sandstone  near  Loch  Maben  (visited  by 
Mr.  Murchison  and  himself  in  1827)  was  rightly  placed  in  the  new 
red  group.  The  lower  divisions  of  the  new  red  sandstone  series  do 
not  appear  to  range  into  this  part  of  Scotland. 

To  the  north  of  the  Galloway  chain  (the  great  southern  grey  wacke 
chain  of  Scotland),  the  new  red  series  almost  dies  away,  and  is  seen 
in  very  few  parts  of  Scotland.  The  author  found  no  traces  of  it 
between  Girvan  and  the  mouth  of  the  Clyde.     Coupling  this  fact 

*  Proceedings,  vol.  ii.  p.  675.  [or  Phil.  Mag.  S.  3.  vol.  xiii.  p.  299.] 


14-2  Geological  Society.  Prof.  Sedgwick  on  the 

with  the  great  development  of  red  sandstones  in  many  parts  of  the 
true  carboniferous  series  of  Scotland,  he  concludes  that  the  highest 
stratified  beds  of  Arran  do  not  represent  the  new  red  sandstone,  but 
(more  probably)  a  portion  of  the  carboniferous  group.  To  the  upper 
conglomerates  of  Arran  there  is  however  no  counterpart  in  England  ; 
and  the  exact  place  of  the  red  beds  which  overlie  them  is  still  left  in 
some  doubt ;  but  these  upper  conglomerates  may  perhaps  be  compared 
with  some  great  trappean  conglomerates  which  are  subordinate  to 
the  Scotch  coal-fields. 

Carboniferous  series. — The  author  briefly  notices  the  changes  in 
this  series  during  its  range  from  the  northern  counties  of  England 
into  the  basin  of  the  Tweed,  where  a  coal-field  occurs  developed  after 
the  Scotch  type,  and  far  below  the  great  coal-field  of  Newcastle.  He 
then  discusses  shortly  the  carboniferous  deposits  of  Scotland,  which 
are  divided  as  follows,  in  descending  order : — 

1 .  The  rich  coal  deposits  with  numerous  beds  of  coal ;  in  their 
subordinate  beds  of  shale,  ironstone,  fire-clay,  and  fossils,  presenting 
the  closest  analogies  to  the  great  English  coal-fields.  Their  exact 
place  in  a  general  scale  cannot  however  be  determined,  as  they  offer 
no  passages,  like  those  above  noticed,  into  any  higher  formation. 

2.  A  great  group  with  many  thin  bands  of  carboniferous  limestone, 
alternating  with  sandstone  and  shale;  and  generally  with  well-defined 
thick  beds  of  limestone  at  the  top  of  the  group,  so  as  to  form  the  base 
of  the  most  productive  coal-fields.  This  group  also  contains  beds  of 
coal,  but  generally  of  inferior  quality.  The  alternating  sandstones 
are  not  unusually  of  a  red  colour. 

3.  Beds  of  red  sandstone,  shale,  &c. — They  undergo  many  modifica- 
tions of  structure  and  colour,  and  are  in  some  places  of  great  thick- 
ness. In  some  of  their  higher  portions  they  contain  coal-plants, 
and  even  thin  bands  of  coal;  but  they  pass  downwards  by  grada- 
tions the  most  insensible,  and  blend  themselves  with  the  old  red 
sandstone.  Examples  of  such  passages  are  found  on  the  north  side 
of  St.  Abb's  Head,  on  the  north  shores  of  the  Solway  Firth,  and  on 
the  coast  of  Ayrshire. 

The  Dumfries- shire  carboniferous  groups  are  developed  after  the 
Scotch  type  above  described ;  which  is  the  more  remarkable,  as  the 
groups  on  the  south  side  of  the  Firth  conform  to  the  English  type. 
Near  Whitehaven  there  is  no  passage  from  the  carboniferous  lime- 
stone to  the  old  red  sandstone ;  and  the  thickest  beds  of  limestone 
are  at  the  bottom,  and  not  (as  in  Scotland)  at  the  top  of  the  calca- 
reous series. 

The  author  then  notices  the  geological  map  of  Scotland,  and 
states  that  Dr.  M'Culloch  has  not  merely  introduced  much  con- 
fusion by  giving  the  mountain  limestone  series  and  the  old  red 
sandstone  a  common  colour ;  but  that  he  has  committed  a  great 
error  in  principle,  by  confounding,  along  a  considerable  part  of  the 
country  bordering  on  the  north  shores  of  the  Solway  Firth,  the  new 
with  the  old  red  sandstone. 

Old  Red  Sandstone. — The  author,  after  briefly  noticing  the  ex- 
traordinary irregularity  in  the  development  of  this  formation  in  the 


English  Stratified  Rocks  below  the  Old  Red  Sandstone,  fyc.  143 

British  Isles,  compares  the  old  red  conglomerates  of  Cumberland 
with  those  on  both  sides  of  the  Galloway  chain.  In  these  localities 
they  often  form  unconnected  masses  resting  on  the  edges  of  the 
greywacke;  but  in  Galloway  they  are  not  only  more  largely  de- 
veloped than  in  the  north  of  England,  but  show,  as  above  stated, 
many  passages  into  the  overlying  carboniferous  groups. 

Ireland. — He  then  briefly  notices  the  sections  which,  in  the  south 
of  Ireland,  connect  the  old  red  sandstone  with  the  overlying  car- 
boniferous deposits,  and  form  a  good  passage  from  one  formation  to 
the  other.  The  sequence  is  complete,  and  there  is  nothing  to  mark 
any  interruption  of  the  deposits.  He  adopts  Mr.  Griffith's  classifi- 
cation, as  most  agreeable  to  the  physical  character  of  the  groups  and 
to  their  suites  of  fossils. 

In  the  south  of  Ireland  the  lower  carboniferous  shales  (of  Mr. 
Griffith)  pass  into  the  state  of  roofing- slates  with  a  transverse  clea- 
vage, resembling  the  black  slates  at  the  base  of  the  culm  measures  of 
Devonshire.  The  great  coal-field  in  the  west  of  the  island  overlies 
the  mountain  limestone ;  but  it  puts  on  the  form  of  the  culm  mea- 
sures of  Devon,  and  was  formerly  considered  as  a  great  transition 
group.  These  facts  appear  to  remove  a  difficulty  in  classification 
which  was  presented  by  the  mineral  structure  of  the  Devon  culm 
series. 

The  author,  by  way  of  conclusion,  affirms  that  the  Scotch  and 
Irish  sections  enable  us  to  show  that  no  new  formations  can  be  in- 
terpolated between  the  old  red  sandstone  and  carboniferous  series, 
inasmuch  as  the  sequence  is  complete.  In  like  manner,  the  sections 
in  the  Silurian  country  show  that  no  member  is  wanting  between 
the  old  red  sandstone  and  the  Ludlow  rock.  Hence  he  concludes 
that,  from  the  lower  divisions  of  the  new  red  sandstone  down  to  the 
Llandeilo  flagstone,  there  is  one  continuous  unbroken  sequence  in 
which  no  term  is  wanting.  Hence  also  the  argument  for  the  true 
place  of  the  Devonian  system  is  complete.  For  any  formation,  with 
fossils  intermediate  between  the  carboniferous  and  Silurian  systems, 
must  have  an  intermediate  position, — must  therefore  be  on  the  par- 
allel of  some  part  of  the  old  red  sandstone,  which  fills  that  whole 
intermediate  position,  But  allowing  the  above  sequence  to  be  com- 
plete, there  may  still  be  great  difficulties  in  fixing  the  lines  of  de- 
marcation by  which  it  is  to  be  finally  subdivided.  For  example,  the 
lower  carboniferous  limestone,  and  the  carboniferous  slates  of  Ire- 
land, appear  to  overlap  and  descend  below  the  base  line  of  the  car- 
boniferous series  of  England :  and  the  same  remark  appears  to  be 
applicable  to  the  lowest  beds  of  the  carboniferous  series  of  Scotland. 
And  there  are  similar  difficulties  in  determining  the  best  base  line 
for  the  old  red  sandstone,  as  appears  from  subsequent  details. 

Sections  of  North  Wales,  %c. — The  author  next  discusses  two 
sections  illustrating  the  structure  of  North  Wales.  One  is  drawn 
from  the  Menai  Straits,  in  a  direction  about  E.S.E.,  so  as  to  cross 
the  Berwyn  chain  and  end  in  the  carboniferous  series  near  Oswestry. 
The  other  is  drawn  from  the  Berwyn  chain  to  the  carboniferous 
limestone  range  on  the  north  side  of  Denbighshire.    The  greater 


144  Geological  Society.  Prof.  Sedgwick  on  the 

portion  of  the  first  section  crosses  the  older  beds  (the  Cambrian 
system)  which  strike  towards  the  N.E.  The  other  section  intersects 
the  upper  series  (Silurian  system)  which  strike  towards  the  N.W., 
passing  (in  some  places  unconformably)  round  the  beds  of  the  older 
system.  From  a  consideration  of  the  whole  evidence  the  rocks  are 
grouped  in  the  ascending  order,  as  follows  : — 

1.  Chlorite  slate,  quartz  rock,  and  mica  slate  of  Anglesea  and 
Caernarvonshire.  These  are  placed  at  the  base  of  the  section,  and 
form  a  distinct  class  ;  and  nothing  is  discovered  in  this  part  of  the 
section  which  is  perfectly  analogous  with  the  Skiddaw  slate,  or  first 
Cumbrian  group,  to  be  after  described. 

2.  The  old  slate  series  of  Caernarvonshire  and  Merionethshire, 
alternating  indefinitely  with  bands  of  porphyry  and  felspar  rock : 
the  group  is  of  enormous  but  unknown  thickness,  and  is  bent  into 
great  undulations,  the  anticlinal  and  synclinal  lines  of  'which  are 
parallel  to  the  strike  of  the  chain.  Through  wide  tracts  of  country 
it  is  without  fossils  ;  but  at  Moel  Hebog,  Snowdon,  and  Glider  Fawr, 
encrinites,  corals,  and  a  few  species  of  bivalves  have  been  discovered 
in  it.  It  ends  with  the  calcareous  beds  which  range  from  Bala  to 
the  neighbourhood  of  Dinas  Mowddy.  This  is  called  the  Lower 
Cambrian  group. 

3.  The  next  group  (the  Upper  Cambrian  group)  commences  with 
the  fossiliferous  beds  of  Bala,  includes  all  the  higher  portion  of  the 
Berwyns,  and  all  the  slate  rocks  of  South  Wales  which  are  below 
the  Silurian  system.  Its  slate  beds  are  less  crystalline,  and  its 
general  structure  is  more  mechanical,  than  the  preceding  group,  and 
it  contains  incomparably  more  fossils,  which  (though  there  are  many 
extensive  portions  of  the  group  without  fossils)  are  disseminated 
through  the  more  calcareous  beds  in  great  abundance.  Many  of 
the  fossils  are  identical  in  species  with  those  of  the  lowest  divisions  of 
the  Silurian  system,  nor  have  any  true  positive  zoological  characters 
of  the  group  been  well  ascertained. 

In  many  parts  of  South  Wales  it  is  separated  from  the  Silurian 
system  by  great  faults  and  derangements  of  the  strata,  marked  by  a 
broad  band  of  rotten  non-fossiliferous  schist.  At  the  north  end 
of  the  Berwyn  chain  it  appears  to  pass  by  insensible  gradations 
into  the  lower  division  of  the  Upper  system  (the  Caradoc  sand- 
stone). 

4.  The  last  natural  group  (the  Silurian  system).  For  all  details 
respecting  this  system  the  author  refers  to  the  abstracts  of  Mr.  Mur- 
chison's  papers,  and  to  his  published  works. 

The  author  then  describes  a  series  of  sections : — 

(1.)  East  of  the  Berwyns,  in  which  the  Caradoc  sandstone  is 
finely  developed ;  containing  the  Llandeilo  flagstone  and  other  cha- 
racteristic calcareous  and  shelly  bands. 

(2.)  The  sections  north  of  the  Berwyns,  connecting  Montgo- 
meryshire with  Denbighshire.  The  ascending  series  derived  from 
these  sections  is  described  as  follows :  — 

(1.)  A  series  of  beds  several  thousand  feet  in  thickness,  and  at 
the  north  end  of  the  Berwyns  apparently  forming  a  passage 


English  Stratified  Rocks  below  the  Old  Red  Sandstone,  fyc.  145 

between  the  Upper  Cambrian  and  lowest  portion  of  the  Silurian 
system. 
(2.)  Bands  of  calcareous  slate  with  numerous  organic  remains  ^>f 

the  "  Caradoc  sandstone,"  surmounted  by  roofing  slate. 
(3.)  Series  of  flagstones,  more  or  less  calcareous,  with  many  Or- 
thoceratites  and  two  species  of  Cardiola,  &c. ;  overlaid  by,  and 
associated  with,  irregular  masses  of  roofing  slate  with  a  trans- 
verse cleavage. 
(4.)  Flagstones  and  rotten  slates,  many  parts  in  an  imperfect  state 
of  induration,  and  the  whole  surmounted  by  the  carboniferous 
limestone. — Of  the  preceding  section  the  lower  part  of  No.  3 
is  identical  with  the  series  of  Long  Mountain  in  the  Silurian 
sections  of  Mr.  Murchison ;  but  No.  4  is  mineralogically  un- 
like anything  he  has  described,  although  it  has  been  found  by 
Mr.  Bowman  to  contain,  in  its  highest  portion,  some  of  the 
fossils  of  the  Upper  Ludlow  rock.    It  appears  from  these  details 
that  the  Silurian  system,  although  its  subdivisions  are  obscure 
from  the  absence  of  the  Wenlock  and  Ludlow  limestones,  is 
very  fully  developed  in  North  Wales. 
An  examination  of  the  few  Snowdonian  fossils  of  the  author  gives 
the  following  results  : — 

(1.)  Impressions  of  corals  (Turbinolopsis  ?)  (Cwm  Idwal  and  Moel 

Hebog). 
(2.)  Stems  of  Encrinites  (Cwm  Idwal). 

(3.)  Orthis  pecten,  0.  Actonia,  0.  flabellulum,  0.  canalis  (Snow- 
don  and  Moel  Hebog). 
He  has  many  fossils  from  different  parts  of  the  Berwyn  chain ; 
and  he  believes  them  (as  stated  in  a  former  abstract)  to  be  nearly 
all  known  Silurian  species,  but  they  have  not  yet  been  carefully 
examined.  He  possesses  also  a  good  series  of  fossils  from  the  eastern 
side  of  the  Berwyns,  and  from  portions  of  the  more  northern  sec- 
tions ;  but  as  the  whole  series  is  unequivocally  Silurian  (extending 
from  the  Llandeilo  flagstone  to  the  Upper  Ludlow  rocks),  he  has 
not  thought  it  at  present  necessary  to  trouble  the  Society  with  any 
enumeration  of  species. 

From  a  review  of  these  facts  he  concludes,  that  in  the  great  sec- 
tion of  North  Wales  there  is  no  positive  zoological  distinction  in 
the  successive  descending  groups,  however  vast  in  thickness  or  di- 
stinct in  mineral  structure.  It  is  not  by  the  addition  of  new  species, 
but  by  the  gradual  disappearance  of  the  species  in  the  higher  groups, 
that  the  successive  groups  are  zoologically  characterized.  Below 
the  Caradoc  sandstone  there  seems  to  have  been  very  few  new  types 
of  creation,  as  far  at  least  as  we  have  learnt  from  any  positive  facts 
in  the  country  here  described.  This  conclusion  is  nearly  in  accord- 
ance with  a  statement  made  by  the  author  in  a  former  paper,  viz. 

"  The  difficulty  of  classification  by  organic  remains  increases  as 
we  descend,  and  is  at  length  insurmountable ;  for  in  the  lowest 
stratified  groups,  independently  of  metamorphic  structure,  all  traces 
of  fossils  gradually  vanish ;  and  the  great  range  of  certain  species 
through  numerous  successive  groups,  and  the  very  irregular  distri- 
Phil.  Mag.  S.  3.  Vol.  2 1 .  No.  1 36.  Aug.  1 842.        L 


146  Geological  Society.  Prof.  Sedgwick  on  the 

bution  of  fossils  even  in  some  of  the  more  fossiliferous  divisions,  add 
greatly  to  the  difficulties  of  establishing  true  definite  groups  even 
within  the  limits  of  our  island.  The  difficulties  are  indefinitely  in- 
creased in  comparing  the  formations  of  remote  continents.  But 
these  circumstances  are  compensated  by  the  magnificent  scale  of 
development  of  the  successive  groups,  and  their  wide  geographical 
distribution.  Taken  together,  they  have  a  great  unity  of  character ; 
and  even  in  remote  continents  they  seem  to  form  a  common  base, 
from  which  we  may  hope  to  compute  the  whole  series  of  secondary 
and  tertiary  deposits  that  surmount  them." 

Cumbrian  groups,  exhibited,  in  ascending  order,  in  a  section  from 
Keswick  through  Kendal  to  Kirkby  Lonsdale  : — 

1.  The  group  of  Skiddaw  Forest,  &c,  the  lower  part  of  which 
rests  on  the  granite,  and  passes  into  a  system  of  crystalline  strata 
resembling  the  rocks  of  the  first  class  in  North  Wales ;  the  upper 
part  abounds  in  a  fine  dark  glossy  clay  slate,  interrupted  here  and 
there  by  beds  of  more  mechanical  structure.  The  whole  is  of  great 
thickness,  almost  without  calcareous  matter,  and  without  any  trace 
of  organic  remains,  and  forms  the  mineral  axis  of  the  Cumbrian 
mountains. 

2.  A  group  essentially  composed  of  quartzose  and  chloritic  roof- 
ing slates  alternating  with  mechanical  beds  of  coarser  structure, 
and  also  with  innumerable  igneous  rocks  (compact  felspar,  felspar 
porphyry,  brecciated  porphyries,  &c.  &c.)  which  partake  of  all  the 
accidents  of  the  slates.  It  is  of  enormous  thickness,  and  rises  into 
the  highest  mountains  of  the  country ;  and  though  chiefly  developed 
on  the  south  side  of  the  preceding  group  (No.  1),  it  also  appears 
extensively  on  the  north  side  of  the  lower  group,  which  thus  forms 
a  mineral  axis- — a  fact  not  yet  noticed  in  any  of  the  published  geo- 
logical maps.  Though  abounding  in  calcareous  matter,  it  has  no 
organic  remains.  This  group  is  bounded  by  calcareous  slates,  which 
extend  from  the  south  end  of  Cumberland  to  the  neighbourhood  of 
Shap  Wells,  and  have  been  described  by  the  author  in  a  former 
paper.     (See  Transactions  of  Geological  Society.) 

3.  The  next  group  extends  from  the  calcareous  slates  (above 
noticed)  to  the  carboniferous  rocks,  &c.  which  surround  and  cut  off 
the  older  series*.  The  highest  part  of  the  ascending  section  is 
shown  on  a  line  which  descends  to  the  Lune  near  Kirkby  Lonsdale. 
The  other  sections  are  much  less  perfect.  The  whole  group  is  sepa- 
rated, provisionally,  into  two  divisions.  • 

The  Lower  division  commences  with  the  calcareous  slates  above 

*  In  a  geological  map  lately  presented  by  the  author  (which  professes 
only  to  be  a  copy  of  a  map  made  by  himself  nearly  twenty  years  since), 
he  represents  all  the  beds  above  the  calcareous  slates  of  one  colour.  He 
does  this,  because  he  is  unable  to  fix  the  demarcations  of  the  several  divi- 
sions of  the  whole  group.  As  he  considered  the  whole  to  represent  the 
Silurian  system  he  wished  to  represent  the  surface  by  three  colours  ;  but 
he  found  it  impossible,  even  approximately,  to  represent  their  boundaries. 
And  even  with  a  simpler  system  of  two  divisions,  he  is  unable,  at  present, 
to  define  correctly  their  line  of  demarcation ;  nearly  all  the  middle  portions 
of  the  sections  being  devoid  of  fossils. 


English  Stratified  Rocks  below  the  Old  Red  Sandstone,  fyc.    1 47 

mentioned*.  The  beds  over  the  calcareous  bands  are  composed  of 
slates  and  flagstones,  hard  bands  occasionally  passing  into  thick,  hard, 
arenaceous  beds  of  greywacke,  &c.  It  is  supposed  to  end  a  little  to 
the  north  of  Kendal ;  but  its  upper  limit  is  not  defined,  and  there  are 
no  distinct  calcareous  bands  to  assist  in  connecting  it  with,  or  sepa- 
rating it  from,  the  upper  division.  The  fossils  derived  from  the  lower 
portion  of  this  division  are  Lower  Silurian.  Among  the  fossils  in  the 
possession  of  the  author,  which  have  as  yet  been  very  imperfectly 
examined,  Mr.  Lonsdale  has  found  among  the  corals  Catenipora, 
Porites,  Favosites,  Ptilodictya,  all  of  known  Lower  Silurian  species, 
and  one  or  two  new  species. 

Among  the  shells  are  three  species  of  Leptaena  and  five  species  of 
Orthis,  all  of  described  Caradoc  sandstone  species ;  in  addition  to 
which  there  are  one  or  two  new  species  of  Orthis.  With  the  above 
are  also  found  Atrypa  affinis  and  A.  aspera;  also  Terebratula  bipartita. 
With  the  above  occur  many  specimens  of  Tentaculites  annulatus ;  also 
several  Trilobites,  among  which  are  Asaphus  Powisii,  Isotelus  Bar- 
riensis,  and  a  new  Paradoxite,  &c. 

All  the  above  fossils  are  found  in  the  calcareous  slates. 

The  Upper  division  is  composed  of  arenaceous  flagstone,  with  im- 
perfect slaty  bands,  and  with  beds  of  hard  greywacke.  It  is  gene- 
rally of  a  grey,  bluish- grey,  or  greenish-grey  colour,  rarely  of  a  red- 
dish colour.  It  has  some  calcareous  portions,  but  no  beds  of  lime- 
stone fit  for  use ;  and,  near  Kirkby  Lonsdale,  ends  with  red  fossilife- 
rous  and  flaggy  beds  containing  concretionary  limestone,  which  are 
overlaid  unconformably  by  the  marls  and  conglomerates  of  the  old 
red  sandstone.  The  fossils  of  the  above  group  (which  is  of  great 
thickness,  though  partially  repeated  by  undulations)  are  of  one  type. 
Several  species  are  new,  e.  g.  two  or  more  species  of  Pterinsea,  &c. : 
but  the  great  majority  of  specimens,  whether  from  the  hills  south  of 
Kendal,  or  from  Kirkby  Moor,  are  Upper  Silurian ;  or  in  the  beds  Mr. 
Murchison  places  at  the  base  of  the  old  red  sandstone  (tilestone). 

The  following  list  is  made  out  by  Mr.  Sowerby  from  what  the 
author  considers  a  very  imperfect  collection  : — 


Terebratula  nucula. 

Orthis  lunata. 

Leptaena  lata.   Very  abundant. 

Spirifera  interlineata. 

Cypricardia  cymbiformis. 

Avicula  rectangularis. 

retroflexa. 


Trochus  helicites. 

Turbo  Williamsii. 

Natica. 

Turritella  obsoleta.  "J  Very 

gregaria.  >  abun- 

conica.     J    dant. 

Orthoceras  trochleare. 
Calymene  Blumenbachii. 


Cucullsea  antiqua. 

Bellerophon  trilobatus. 

From  the  above  lists  we  obtain  this  definite  information,  that  the 

*  When  a  former  abstract  was  published,  the  author  placed  these  beds 
on  the  parallel  of  the  Bala  limestone,'  over  which  the  slates  of  the  Ber- 
wyns  and  all  the  Devonian  slates  were  provisionally  arranged ;  but  since 
the  removal  of  the  Devonian  system  to  a  place  superior  to  the  Silurian,  the 
sections  present  no  real  ambiguity.  The  calcareous  slates  above  described 
are  true  Lower  Silurian,  and  not  a  part  of  any  sub-Silurian  group  that  is 
represented  by  the  older  rocks  of  South  Wales, 

L2 


]48  Geological  Society:  Prof.  Sedgwick  on  the 

lower  division  is  Lower  Silurian,  and  that  the  upper  division  ends  at 
the  very  top  of  the  Silurian  system,  and  includes  beds  which  have 
been  classed  with  the  old  red  sandstone — an  arrangement  which  is 
natural  in  South  Wales,  but  is  not  sanctioned  by  the  Westmoreland 
sections. 

The  want  of  good  mineral  or  fossil  groups  to  distinguish  the  mid- 
dle portion  of  the  section,  makes  the  real  difficulty  of  representing  the 
divisions  on  a  map. 

The  author  then  briefly  noticed  two  other  sections  ;  one  from  the 
Shap  granite,  through  the  fossiliferous  slates,  &c,  to  Howgill  Fells. 
These,  in  their  range  southwards  through  Middleton  Fells,  &c,  are 
placed  in  the  upper  division,  though  not  in  the  highest  part  of  it, 
which  is  described  above.  They  contain  very  few  fossils,  but  those 
which  have  been  found  are  of  the  Upper  Silurian  system. 

Lastly,  the  author  briefly  mentioned  the  phenomena  of  another 
ascending  transverse  section  from  the  western  end  of  the  calcareous 
slates,  as  follows  : — 

(1.)  Calcareous  slates  (Caradoc)  of  Milium  in  Cumberland. 

(2.)  Quartzose  flagstone,  coarse  pyritous  shale  and  slate,  &c. 

(3.)  Roofing  slates  of  Kirkby  Jreleth. 

(4 .)  Second  band  of  calcareous  slates,  also  with  Lower  Silurian  fossils . 

(5.)  Upper  series  of  flags  and  roofing-slate  extending  to  the  neigh- 
bourhood of  Ulverston  ;  and  in  turn  overlaid  by  coarser  beds,  which, 
however,  in  a  section  continued  to  Morecambe  Bay,  did  not  show 
any  of  the  upper  fossil  bands. 

Ireland  and  South  of  Scotland. — The  author  then  shortly  notices 
some  sections  in  the  counties  of  Waterford  and  Kerry  (to  which  he 
was  conducted  by  Mr.  Griffith).  They  exhibit  a  fine  sequence  of 
true  Lower  Silurian  rocks,  but  do  not  show  their  relations  (at  least 
in  any  section  seen  by  the  author)  to  the  older  non-fossiliferous  slates 
of  the  south  of  Ireland.  Hence,  though  excellent  examples  of  a  group 
of  upper  fossiliferous  slates,  they  do  not  offer  any  help  as  to  the 
number  and  order  of  the  natural  groups  into  which  the  great  in- 
fra-carboniferous series  may  be  conveniently  divided.  He  then  points 
out  that  the  grouping  of  the  older  strata  in  the  south  of  Ireland,  now 
given  by  Mr.  Griffith,  is  not  only  sanctioned  by  the  sections,  but 
gets  rid  of  a  great  supposed  anomaly, — viz.  the  re-appearance  of  the 
carboniferous  fossils  at  different  levels  on  a  general  descending  sec- 
tion of  the  older  rocks  of  Ireland. 

The  author  then  briefly  notices  the  fossils  in  the  true  Silurian  rocks 
in  the  north  of  Ireland,  in  progress  of  publication  by  Captain  Port- 
lock.  They  form  an  admirable  series,  but  the  sections  do  not  appear 
to  connect  the  group  of  rocks  containing  them  with  the  older  forma- 
tions, so  as  to  lend  much  help  in  their  subdivisions  or  grouping. 

Mourne  mountains,  Galloway  chain,  SfC. — After  a  few  details  re- 
specting the  mineral  structure,  strike,  altered  rocks,  granite  veins, 
&c,  of  Downshire,  the  author  proceeds  to  notice  the  Galloway  chain 
(which  extends  from  the  Mull  of  Galloway  to  St.  Abb's  Head).  Its 
prevailing  strike,  like  that  of  the  Mourne  mountains,  is  about  N.E. 
by  E. ;  and  this  is  sometimes  persistent,  even  in  the  neighbourhood 


English  Stratified  Rocks  below  the  Old  Red  Sandstone,  fyc.  1 49 

of  protruded  masses  of  granite.  It  is  generally  made  up  of  beds  of 
a  hard  arenaceous  greywacke,  sometimes  of  a  very  coarse  structure, 
sometimes  finer,  and  occasionally  passing  into  a  good  roofing  slate, 
— generally  it  is  without  fossils  ;  but  the  Graptolites  foliaceus  (first 
noticed  by  Mr.  Carrick  Moore)  occurs,  though  rarely,  among  the 
finer  slates.  In  these  respects  the  chain  is  analogous  to  that  in 
Pembrokeshire,  where  the  same  fossil  occurs  in  the  slates  below  the 
Lower  Silurian  rocks  of  Mr.  Murchison. 

He  then  notices  a  ridge  of  rocks  visited  by  Mr.  Carrick  Moore 
and  himself,  which  breaks  out  from  under  the  carboniferous  basin  of 
Girvan- water  in  Ayrshire.  It  contains  many  fossils,  among  which 
Mr.  Sowerby  finds  three  or  four  new  species  of  Orthis,  Tentaculites, 
Atrypa,  and  one  or  two  species  of  Terebratula.  Near  it,  and  probably 
forming  a  part  of  it,  is  a  small  mass  of  limestone,  with  many  corals 
and  some  Trilobites,  the  latter  unfortunately  lost  by  the  author. 
Mr.  Lonsdale  states  that  the  corals  are  difficult  and  obscure,  but 
there  is  a  true  Favosites  fibrosa,  probably  also  a  Favosites  spongites  ; 
and  there  are,  among  the  specimens,  several  small  hemispherical 
corals  which  may  be  young  Stromatopora  concentrica.  From  this 
evidence  he  would  be  inclined  to  refer  the  limestone  to  an  Upper 
Silurian  or  Devonian  group.  From  the  number  of  Orthidia,  Mr. 
Sowerby  would  refer  the  fossiliferous  slates  to  the  Lower  Silurian ; 
but  the  whole  mass,  including  slates  and  limestone,  is  of  small  extent, 
and  seems  to  form  but  one  group,  which  maybe  considered  as  Silurian. 

To  show  the  position  of  these  beds,  the  author  gives  a  transverse 
section  from  the  Solway  Firth  over  the  Galloway  chain  to  the  fossil 
group  above  mentioned.  The  groups  on  the  section  appear  in  the 
following  order,  beginning  at  the  south  end  : — 1.  Old  red  sandstone. 
2.  Greywacke  of  the  Galloway  chain.  3.  Granite.  4.  Greywacke 
of  the  Galloway  chain  on  the  north  side  of  the  axis.  5.  Unconform- 
able masses  of  old  red  sandstone.  6.  Coal-basin  of  Girvan- water. 
7.  Fossiliferous  slates  and  limestone  rising  from  under  the  coal  series. 

Conclusion. — It  appears,  from  the  preceding  synopsis,  that  there  is 
a  continuous  and  apparently  uninterrupted  sequence  of  deposits 
from  the  lower  beds  of  the  new  red  sandstone  formation  to  the  low- 
est known  strata  of  England ;  that  beds  of  masses  of  limestone  ap- 
pear here  and  there  in  the  descending  series  ;  and  (with  the  excep- 
tion of  the  mountain  limestone)  that  they  are  neither  so  continuous 
nor  so  fixed  in  their  place  as  to  offer  any  good  bases  for  the  general 
classification  of  the  groups ;  that  the  divisions  into  which  the  de- 
scending series  may  be  separated  often  pass  into  one  another,  so  as 
to  make  their  demarcations  doubtful  or  arbitrary;  and  that,  in  the 
lower  divisions,  organic  remains  gradually  disappear.  The  great  di- 
visions of  the  descending  series  hitherto  ascertained  are  as  follows  : — 

1.  Carboniferous. — Passing  in  some  places  at  its  upper  limits  into 
the  lower  new  red  sandstone. 

2.  Old  red  sandstone. — Passing  in  its  upper  limits  (Scotland  and 
Ireland)  into  the  first  division,  and  including  the  slate  rocks,  &c,  of 
Devon  and  a  part  of  Cornwall. 

3.  Silurian. — Passing  in  its  upper  groups  into  the  old  red  sandstone . 


1 50  American  Philosophical  Society. 

All  the  country  described  by  Mr.  Murchison  as  superior  to  the  Llan- 
deilo  flags,  separated  into  three  groups — upper,  middle,  and  lower. 
East  of  Berwyn  chain,  lower  group.  North  of  the  Berwyn  chain 
(Denbighshire),  upper,  middle,  and  lower  groups ;  but  with  a  new 
mineral  type,  and  without  any  upper  bands  of  limestone.  West- 
moreland :  upper  group  largely  developed,  and  including  fossils  of  the 
tilestone ;  middle  group  without  limestone  bands  or  fossils ;  lower 
group  with  many  characteristic  fossils.  Horton  and  Ingleton,  mid- 
dle and  upper  groups.  Ireland  (Waterford  and  Kerry),  lower  group. 
Scotland  (Ayrshire),  Silurian  group,  but  not  defined. 

4.  Sub-Silurian,  or  Upper  Cambrian. — The  old  rocks  of  South  "Wales 
below  the  preceding  division ;  containing  Graptolites,  but  no  well- 
defined  calcareous  band,  and  very  few  fossils.  A  part  of  the  Berwyn 
chain  based  on  the  Bala  limestone.  The  upper  part  of  the  roofing 
slates,  &c,  of  Cumberland,  immediately  under  the  Caradoc  limestone 
(of  Coniston,  &c).  Slates  of  Charnwood  Forest?  Slates  of  the 
Mourne  mountains,  of  the  Galloway  chain,  &c. 

5.  Lower  Cambrian. — The  great  slate  group  of  North  "Wales  be- 
low the  Bala  limestone.     The  old  roofing  slates  of  Cumberland. 

6.  Lower  Cumbrian,  or  Skiddaw  slate. — Slates  of  Skiddaw  Forest, 
lower  part  metamorphic.  Provisionally  arranged  in  this  place,  the 
chlorite  slates,  &c,  of  Anglesea  and  Caernarvonshire. 


AMERICAN  PHILOSOPHICAL  SOCIETY. 

January  21, 1842. — Dr.Hare  made  an  oral  communication  respect- 
ing a  new  aethereal  liquid  which  he  had  succeeded  in  obtaining. 

He  mentioned  that  he  had  procured,  by  means  of  hyponitrite  of 
soda,  diluted  sulphuric  acid  and  pyroxylic  spirit,  an  aethereal  liquid, 
in  which  methyl  (C3  H3)  might  be  inferred  to  perform  the  same  part 
as  aethyl  (C4  H5)  in  hyponitrous  aether.  In  fact,  by  substituting  py- 
roxylic spirit  for  alcohol,  this  new  aether  was  elaborated  by  the  pro- 
cess for  hyponitrous  aether,  of  which  he  had  published  an  account  in 
the  Society's  Transactions,  vol.  vii.  part  2. 

The  compound  which  was  the  subject  of  his  communication  had  a 
great  resemblance  to  alcoholic  hyponitrous  aether,  similarly  evolved, 
in  colour,  smell  and  taste,  although  there  was  still  a  difference  suffi- 
cient to  prevent  the  one  from  being  mistaken  for  the  other. 

Pyroxylic  spirit  appeared  to  have  a  greater  disposition  than  alcohol 
to  combine  with  the  aether  generated  from  it,  probably  in  consequence 
of  its  having  less  affinity  for  water.  The  boiling  point  appeared  to 
be  nearly  the  same  in  both  of  the  aethers  ;  and  in  both,  in  consequence 
of  the  escape  of  an  aethereal  gas,  an  effervescence,  resembling  that  of 
ebullition,  was  observed  to  take  place  at  a  lower  temperature  than 
that  at  which  the  boiling  point  became  stationary.  The  aethereal  gas, 
of  which  Dr.  Hare  had  given  an  account  in  his  communication  re- 
specting hyponitrous  aether,  seemed  to  have  escaped  the  attention  of 
European  chemists;  and,  even  after  it  had  been  noticed  by  him, 
seemed  to  be  overlooked  by  Liebig,  Kane,  and  others,  in  their  subse- 
quent publications. 

Dr.  Hare  attached  the  more  importance  to  his  success  in  producing 


American  Philosophical  Society.  151 

the  aether  which  was  the  subject  of  his  communication,  since,  agree- 
ably to  Liebig,  no  such  compound  exists,  and  it  is  to  be  inferred 
that  efforts  to  produce  it  had  hitherto  failed.  It  was  presumed  that 
this  would  excite  no  surprise,  when  the  difference  was  considered 
between  the  consequences  of  the  reaction  of  nitric  acid  with  py- 
roxylic  spirit  and  with  alcohol. 

The  liquid  last  mentioned  is  now  viewed  as  a  hydrated  oxide  of 
a;thyl,  while  pyroxylic  spirit  is  viewed  as  a  hydrated  oxide  of  methyl. 
When  alcohol  is  presented  to  nitric  acid,  a  reciprocal  decomposition 
ensues.  The  acid  loses  two  atoms  of  oxygen,  which,  by  taking  two 
atoms  of  hydrogen  from  a  portion  of  the  alcohol,  transforms  it  into 
aldehyd ;  while  the  hyponitrous  acid,  resulting  inevitably  from  the 
partial  deoxidizement  of  the  nitric  acid,  unites  with  the  base  of  the 
remaining  part  of  the  alcohol.  But  when  pyroxylic  spirit  is  pre- 
sented to  nitric  acid,  this  acid,  without  decomposition,  combines  with 
methyl  the  base  of  this  hydrate ;  so  that,  as  no  hyponitrous  acid  can 
be  evolved,  no  hyponitrite  can  be  produced.  Thus,  in  the  case  of 
the  one,  there  can  be  no  aethereal  hyponitrite ;  in  that  of  the  other, 
no  aethereal  nitrate. 

Dr.  Hare  regretted  that  Liebig  should  not  have  been  informed  of 
the  improved  process  for  hyponitrous  aether,  to  which  he  had  referred 
in  commencing  his  communication.  Instead  of  recommending  a  re- 
sort to  that  process,  it  was  advised  that  the  fumes,  resulting  from 
the  reaction  of  nitric  acid  with  fecula,  should  be  passed  into  alcohol, 
and  the  resulting  vapour  condensed  by  means  of  a  tube  surrounded 
by  a  freezing  mixture. 

This  process  Dr.  Hare  had  repeated,  and  found  the  product  very 
inferior  in  quantity  and  purity  to  that  resulting  from  the  employment 
of  a  hyponitrite.  In  this  process,  nascent  hyponitrous  acid,  as  libe- 
rated from  a  base,  is  brought  into  contact  with  the  hydrated  oxide. 
In  the  process  recommended  by  Liebig,  evidently  this  contact  could 
not  take  place  ;  since  it  was  well  known  that  hyponitrous  acid  could 
not  be  obtained  by  subjecting  fecula  and  nitric  acid  to  distillation, 
and  condensing  the  aeriform  products*. 

March  4th. — Dr.  Goddard  presented  specimens  of  Daguerreotype 
on  a  surface  of  gilded  silver,  and  stated  that  the  surface  of  iodide  of 
gold  was  more  susceptible  to  the  Daguerreotype  action  of  light  than 
that  of  the  iodide  of  silver,  that  the  surface  of  the  plate  might  be 
polished  without  injury  before  the  action  of  the  iodine,  and  that  the 
lights  came  out  better  than  on  the  silver  surface. 

April  1 . — Dr.  Hare  related  some  experiments,  showing  that  the 
vapour  of  nascent  steam,  generated  by  the  hydro-oxygen  flame,  was 
not  productive  of  electricity. 

He  observed  that,  before  his  late  voyage  to  Europe,  he  had  made 
some  experiments  in  order  to  ascertain  whether  any  electricity  was 

*  The  process  alluded  to  is  as  follows  : — Seven  parts  of  acid,  eight  parts 
of  alcohol,  fourteen  parts  of  water,  and  fourteen  of  hyponitrite  being  pre- 
pared, add  seven  parts  of  water  to  the  salt  and  seven  to  the  acid,  and  allow 
the  mixture  to  cool.  The  saline  solution  and  alcohol  are  introduced  into 
a  tubulated  retort,  of  which  the  recurved  and  tapering  beak  enters  a  tube, 
which  occupies  the  axis,  and  descends  through  the  neck  of  an  inverted  bell- 


1 52  American  Philosophical  Society. 

given  out  by  the  flame  of  the  hydro-oxygen  blowpipe,  or  by  the  ele- 
ments of  water  during  their  conversion  into  steam. 

The  unexpected  electrical  results,  previously  ascertained  respect- 
ing high  steam*,  naturally  gave  importance  to  this  inquiry,  the  re- 
sult of  which  he  had  no  previous  opportunity  of  communicating  to 
the  Society. 

Even  the  flame  produced  by  means  of  a  very  powerful  hydro- 
oxygen  blowpipe  was  not  found  to  be  productive  of  electrical  indica- 
tion, when  allowed  to  act  upon  a  metallic  mass  supported  upon  the 
canopy  of  an  extremely  delicate  electroscope.  As  it  was  suggested 
that,  the  flame  being  a  conductor,  the  electricity  evolved  might  retro- 
cede  by  it  to  the  metallic  pipe,  the  experiment  was  modified  in  the 
following  way: — 

The  mixture  of  one  part  of  oxygen  and  two  of  hydrogen  being,  as 
in  the  first  instance,  condensed  within  a  mercury  bottle,  was  made,  by 
means  of  a  valve  cock  and  safety  tube,  to  communicate,  through  a 
glass  tube,  with  a  jet  pipe  of  platinum,  a  foot  in  length  and  in  bore. 

The  apparatus  being  thus  arranged,  and  the  cock  so  adjusted  as 
to  allow  the  gaseous  mixture  to  escape  through  the  jet  pipe  with 
sufficient  celerity,  a  flame  of  hydrogen  was  applied  to  the  outside  of 
this  pipe  about  the  middle.  By  these  means,  the  temperature  being 
raised  so  as  to  cause  the  elements  of  water  to  combine,  the  flame  was 
removed,  the  heat  being  sufficiently  kept  up  by  the  internal  com- 
bustion. Thus  that  which  entered  at  one  end  of  the  tube  as  gas, 
came  out  at  the  other  as  steam.  Under  these  circumstances,  a  single- 
leaf  electrometer,  more  susceptible  than  a  condensing  electrometer, 
was  not  indicative  of  any  electrical  excitement,  either  in  the  insulated 
jet  tube,  or  in  any  body  on  which  the  steam  was  allowed  to  condense. 

Dr.  J.  K.  Mitchell  having  expressed  a  wish  to  see  these  experi- 
ments, they  were  repeated,  with  his  assistance,  with  the  same  results. 

Dr.  Hare  also  mentioned  that  he  had  observed  an  sethereal  liquid 
to  subside  on  the  addition  of  pure  pyroxylic  spirit  to  an  aqueous 
solution  of  hypochlorous  acid,  obtained  by  passing  chlorine  into 
water  in  contact  with  bioxide  of  mercury. 

Having  separated  the  sether  thus  produced,  he  found  it  to  have  an 
agreeable  and  peculiar  fragrance.  Like  oil  of  wine,  it  could  not  be 
distilled  without  decomposition.  There  was  an  effervescence  at  the 
temperature  of  140°  F. ;  but  the  boiling  point  rose  beyond  that  of  a 

glass,  so  as  to  terminate  within  a  tall  phial.  Both  the  tube  and  phial  must 
be  surrounded  by  ice  and  water.  The  diluted  acid  is  then  added  gradually. 
A  water-bath,  blood-warm,  is  sufficient  to  cause  all  the  aether  to  come  over. 

Agreeably  to  another  plan,  the  materials,  previously  refrigerated  by  ice, 
are  introduced  into  a  bottle,  also  similarly  refrigerated.  Under  these  cir- 
cumstances the  aether  soon  forms  a  superstratum  which  may  be  separated 
by  decantation. 

This  last-mentioned  process  does  not  answer  so  well  for  the  hyponitrite 
of  methyl,  on  account  of  the  pyroxylic  spirit  being  prone  to  rise  with  the 
aether ;  yet  the  spirit  may  be  separated  from  the  aether  by  anhydrous 
chloride  of  calcium. 

*  [See  Phil.  Mag. Third  Series,  vol.  xvii.  p. 370,  and  various  subsequent 
papers  in  that  volume,  and  in  vols,  xviii.  xix.  xx.— Edit.] 


Intelligence  and  Miscellaneous  Articles.  153 

boiling  water-bath.  When  a  naked  flame  was  applied,  the  aether, 
previously  colourless,  acquired  a  yellowish  wine  colour,  and,  by  the 
crackling  evolution  of  vapour,  indicated  decomposition. 

When  the  liquid  hypochlorous  acid  was  subjected  to  the  process 
of  distillation,  before  the  addition  of  the  spirit,  an  aether  resulted 
which  floated  on  the  solution,  and  which  appeared  to  differ  from  that 
obtained  as  first  mentioned. 

Dr.  Hare  made  these  observations,  and  those  previously  communi- 
cated respecting  the  hyponitrite  of  methyl,  by  the  aid  of  a  small 
quantity  of  pure  pyroxylic  spirit,  supplied  to  him  by  his  friend  Dr. 
Ure,  and  regretted  that  both  ill-health  and  the  exhaustion  of  his 
stock  of  spirit  had  prevented  him  from  making  further  observations 
and  experiments,  tending  to  decide  whether  the  aethers  obtained,  as 
he  had  described,  were  either  or  both  hypochlorites,  or  whether  mer- 
cury entered  into  the  composition  of  the  heavier  aether.  This  there 
was  some  reason  for  believing ;  since,  when  boiled  to  dryness  at  a 
high  temperature,  a  reddish  residuum  was  apparent,  which  being  re- 
dissolved,  and  a  small  strip  of  copper  immersed  in  the  resulting  so- 
lution, a  minute  deposition,  apparently  metallic,  was  observable. 

XXV.  Intelligence  and  Miscellaneous  Articles. 

FOURTH  MEETING  OF  THE  ITALIAN  CONGRESS  OF  MEN  OF 
SCIENCE. 

A  CIRCULAR  has  arrived  in  England  announcing  that  the  scien- 
tific men  of  Italy  will  meet  this  year  at  Padua  on  the  15  th  of 
September,  under  the  presidency  of  Signors  Nicolo  da  Rio  and  Gio- 
vanni Santini,  both  of  the  University  of  Padua.  The  warmest  invi- 
tations are  given  to  such  scientific  persons  of  all  nations  as  may  be 
disposed  to  attend  the  meeting. 


ON  THE  EARTHQUAKE  FELT  IN  PARTS  OF  CORNWALL,  ON 
FEBRUARY  17,  1842*. 

At  the  last  annual  meeting  of  the  Royal  Institution  of  Cornwall, 
a  communication  was  read  from  Mr.  William  Hen  wood,  recording 
three  shocks  of  earthquakes,  which  had  been  felt  at  different  periods 
in  the  county.  In  addition  to  these,  the  following  are  mentioned  in 
a  paper,  by  Mr.  D.  Milne,  *  On  the  Shocks  of  Earthquakes  felt  in 
Great  Britain.' 

1757,  July  15. — The  shock  of  an  earthquake  was  felt  at  Falmouth, 
at  seven  p.m.,  attended  with  great  noise.  It  came  from  the  south- 
west, and  was  heard  in  the  mines  of  Cornwall  at  a  depth  of  seventy 
fathoms.  The  shock  extended  as  far  east  as  Liskeard,  and  as  far 
north  as  Camelford.  "  Several  small  risings  as  big  as  mole-hills 
were  observed  in  the  morning  before  the  shock  happened,  on  the 
sands  of  the  beach,  having  a  black  speck  in  the  middle  of  the  top, 
as  if  something  had  issued  from  it.     From  one  of  the  risings  be- 

*  From  the  Report  of  the  Polytechnic  Society  of  Cornwall  for  1841. 
The  particulars  were  collected  by  Mr.  Robert  Hunt,  Secretary. 


154-  Intelligence  and  Miscellaneous  Articles. 

tween  the  hollows  there  issued  a  strong  gush  of  water,  about  as 
thick  as  a  man's  wrist.  For  a  week  before  the  shock  the  weather 
had  been  warm  and  sultry.  In  one  of  tbe  mines  the  earth  was  felt 
to  move  with  a  prodigious  swift  and  apparently  horizontal  tremor." 
— Gent.'s  Mag.,  v.  xxix.  146  ;  and  Transactions  R.S.S.* 

1759,  Feb.  24. — The  shock  of  an  earthquake  was  felt  at  Liskeard. 
A  bright  aurora  borealis  seen  in  the  evening. 

From  the  statements  of  several  persons  residing  at  Budock  and  at 
Stithians,  it  appears  some  disturbance  was  felt  in  1836. 

As  this  paper  is  designed  to  record  as  correctly  as  possible  all 
the  circumstances  connected  with  the  phenomenon  of  the  17th  of 
February,  1842,  I  shall  without  hesitation  state,  in  the  first  place, 
the  manner  in  which  it  was  felt  at  my  own  residence,  in  Berkeley 
Vale,  Falmouth. 

About  twenty  minutes  before  nine  a.m.,  I  heard  a  peculiar  rum- 
bling sound,  more  like  the  moaning  of  the  wind  than  thunder,  which 
was  immediately  followed  by  a  shaking  of  the  doors  and  windows  of 
the  house,  the  whole  effect  lasting  about  half  a  minute. 

In  the  environs  of  the  town  of  Falmouth,  the  noise  particularly 
attracted  attention,  and  although  but  few  speak  of  any  tremor,  yet 
all  describe  it  either  as  resembling  the  fall  of  a  heavy  body,  or  like  a 
distant  explosion.  Many  persons  were  fully  persuaded  a  steam  ves- 
sel had  blown  up  in  the  harbour. 

At  Penryn  the  disturbance  was  more  decidedly  felt  than  at  Fal- 
mouth, and  most  persons  speak  of  the  doors  of  their  houses  shaking, 
and  some  of  the  earthenware  rattling  on  the  shelves :  many  left 
their  houses  in  alarm.  It  has  been  stated  that  the  tide  rose  and  fell 
again  suddenly ;  such  does  not,  however,  appear  to  have  been  the 
case  :  an  individual,  who  observed  the  tide-mark  at  the  bridge  at  the 
time,  says  that  no  variation  was  produced. 

At  Enys,  one  mile  from  Penryn,  the  shock  is  described  by  J.  S. 
Enys,  Esq.,  "  as  a  noise  twice  quickly  repeated,  like  a  heavy  weight 
falling  and  rebounding:"  this  gentleman  also  speaks  distinctly  of 
the  shaking  of  articles  in  the  rooms. 

At  Ponsanooth  and  down  the  valley  to  Perranwharf,  the  shock  is 
described  by  all  persons  as  considerable,  and  the  first  impression  was 
that  the  powder  mills  in  the  neighbourhood  had  exploded.  Along 
this  line,  still  extending  to  the  north,  the  disturbance  appears  to 
have  been  equally  felt.  The  inhabitants  of  the  villages  of  Comfort 
and  Lanner,  under  Cam  Marth,  about  the  junction  of  the  granite 
and  killas  or  clay-slate,  left  their  houses,  thinking  that  some  serious 
explosion  had  occurred  at  the  neighbouring  mine ;  and  on  the  south- 
ern side  of  the  granite  hill,  Cam  Marth,  the  people  felt  a  great  tre- 
mor. An  intelligent  person,  captain  of  Poldory  mine,  describes  it 
thus  : — "  I  imagined  some  of  the  empty  railroad  waggons  had  been 
let  go  at  the  top  of  the  incline,  and  were  rapidly  rushing  past  the 
door  of  my  house  :  my  neighbour,  a  widow  woman,  ran  out  shriek- 
ing that  the  side  of  her  house  was  coming  in."     In  Poldory,  the 

*  We  presume  this  is  intended  to  refer  to  the  Transactions  of  the  Royal 
Society  of  Edinburgh,  in  which  Mr.  Milne's  paper  appeared. 


Intelligence  and  Miscellaneous  Articles.  155 

western  part  of  the  United  Mines,  the  shock  was  felt  by  the  men 
working  130  fathoms  below  the  surface  ;  but  it  does  not  appear  to 
have  been  noticed  at  all  in  the  eastern  part  of  these  or  the  Consoli- 
dated Mines.     At  Tresavean  mine  the  shock  was  felt  at  all  depths. 

The  people  dwelling  to  the  north  of  Cam  Marth  do  not  appear 
to  have  been  conscious  of  anything  uncommon ;  the  noise  was  heard 
at  Tuckingmill  and  Pool,  but  was  attributed  to  the  discharge  of  a 
cannon  at  a  great  distance,  so  faint  and  indistinct  was  it.  In  the 
south  parts  of  the  parish  of  Camborne  the  noise  was  also  heard,  but 
no  tremor  felt. 

In  the  parish  of  Stithians  the  shock  was  decidedly  felt,  and  seve- 
ral persons  in  the  village,  who  were  taking  breakfast  at  the  time, 
speak  of  their  tables  having  been  shaken,  and  the  cups  and  saucers 
having  clattered.  It  appears  to  have  been  felt  with  equal  intensity 
in  the  parishes  of  Mabe  and  Constantine,  perhaps  more  powerfully 
in  the  latter  than  in  any  other  part. 

An  intelligent  correspondent,  who  has  kindly  been  at  some  pains 
to  procure  authentic  accounts,  thus  writes: — "On  the  morning  of  the 
17th  a  shaking  of  the  earth  was  felt  in  this  village,  accompanied  by 
a  sound  resembling  distant  thunder.  At  one  house,  where  some 
men  were  working,  they  left  their  work  and  ran  out  to  know  what 
it  was  that  gave  the  shock.  In  another  a  book  fell  from  the  book- 
shelf to  the  floor.  Adjoining  the  village,  where  there  were  some 
persons  in  bed  at  the  time  from  sickness,  the  beds  were  felt  to  shake ; 
a  door  was  even  seen  to  fly  open  from  the  shock.  At  Wheal  Vy- 
vyan  mine  some  men  working  about  twenty  or  thirty  fathoms  under 
ground  also  felt  it  very  distinctly ;  and  one  man,  who  was  leaning 
against  a  rock  at  the  time,  still  more  so.  My  wife  also  felt  it,  and 
it  appeared  to  her  as  if  the  roof  of  the  house  was  falling  in." 

At  Helstone  the  disturbance  was  considerable.  Mr.  Moyle  of 
that  town  thus  describes  it : — "  While  at  breakfast,  about  half-past 
eight,  I  started  suddenly  from  my  chair,  with  the  impression  that  a 
heavy  truck  had  run  suddenly  down  the  stone  steps  of  a  passage 
forming  a  back  entrance  to  my  premises."  At  Nansloe,  half  a  mile 
south  of  Helstone,  the  servants  say  the  earthenware  evidently  clat- 
tered ;  and  the  same  was  experienced  at  Trevarno,  two  miles  north- 
west of  the  town.  Captain  Richards,  of  Wheal  Vor  mine,  situate  to 
the  west  of  Helstone,  writes  as  follows  : — "  The  shock  of  the  earth- 
quake on  the  17  th  was  very  distinctly  heard  and  felt  at  this  mine, 
175  fathoms  under  the  surface ;  also  at  the  80  fathom  level  under 
the  surface.  It  was  also  felt  at  Penhale  mine  50  fathoms  under  the 
surface,  and  by  several  persons  within  a  mile  of  Wheal  Vor  mine. 
It  was  very  distinctly  heard  and  felt  near  Godolphin,  and  in  and  about 
Great  Work  mine ;  also  at  Wheal  Penrose  mine  near  Porthleaven." 

It  does  not  appear  to  have  been  very  evident  at  Porthleaven. 

From  West  Wheal  Virgin,  in  the  parish  of  St.  Hilary,  I  have  the 
following  communication  from  Captain  Henry  Francis  : — "  A  little 
before  nine  on  the  morning  of  the  17  th,  some  of  our  men  at  work 
in  the  100  fathom  level,  in  the  south  lode,  felt  a  shock,  and  as  it 
were  a  rush  of  air,  so  much  so  that  one  of  the  candles  was  put  out  by 


156  Intelligence  and  Miscellaneous  Articles. 

it,  accompanied  by  a  noise  which  made  them  think  that  one  of  our 
shafts  had  crushed  in,  or  runned  together ;  but  on  examining  with 
Capt.  Crose,  who  was  in  the  mine,  we  could  find  nothing  at  all  amiss, 
or  any  cause  for  the  shock." 

This  appears  to  be  the  most  westerly  part  at  which  the  tremor 
was  felt,  and  although  the  noise  was  heard  away  to  the  south,  to- 
wards the  Lizard,  it  is  clear  it  was  much  diminished  in  force. 

On  referring  to  a  geological  map  of  the  county,  it  will  be  found 
that  the  greatest  effects  were  produced  near  the  edge  of  the  granite 
mass,  which  extends  from  the  north-east  to  the  south-west,  from 
Cam  Marth  to  the  south  of  Penryn.  Although  it  was  felt  at  Fal- 
mouth, Helstone,  and  other  places  which  are  on  the  clay-slate,  yet 
all  my  inquiries  go  to  show  that  it  diminished  rapidly  in  force,  as 
the  distance  from  the  granite  increased*. 

A  gentleman  of  Helstone  says,  "  I  felt  it  very  sensibly,  and  my 
house  shook,  but  I  experienced  an  effect  on  the  sight  which  I  always 
find  attends  electricity ;"  from  which  he  appears  inclined  to  deem 
the  disturbance  as  atmospheric.  Had  that  been  the  case,  it  would 
not  have  been  felt  in  the  mines  ;  but  it  is  not  improbable  that  a 
manifestation  of  electricity  may  have  attended  this  disturbance  of 
the  earth. 

ON  THE  BLUE  COLOUR  OF  ULTRAMARINE.      BY  M.  ELSNER. 

According  to  all  analyses  hitherto  published,  ultramarine  is  com- 
posed principally  of  soda,  alumina,  silica  and  sulphur,  as  shown  by 
the  following  statements  : — 

Lapis  Lazuli, 
(Clement  Desormes.) 

Soda 23-2 

Alumina     34-8 

Silica 35-8 

Sulphur 31 

Carbonate  of  lime  . .      3*1 


(Varrentrapp.) 

9-09 

31*67 

45-50 

0-95 

Lime 

3-52 

0-86 

Sulphuric  acid .... 

0-42 
5-89 
012 

Artificial  Ultramarine  of  Paris.  4t1^M  V^^  rnanufacture 

(C.  G.  Gmelin.)  (Varrentrapp.) 

Soda  (mixed  with  potash)   12-063     Soda 21*47 

Lime   1*546     Potash 1-75 

Alumina 22-000     Lime 0*02 

Silica 47-306     Alumina    23-30 

Sulphuric  acid    4-679     Silica     45*00 

Sulphur 0-188     Sulphuric  acid 3'83 

Resineus  substance,  sul- 1     lo.oia     Sulphur 1'683 

phur  and  loss.  J  Iron 1-063 

*  Mr.  Hunt  here  adds  some  remarks  on  the  condition  of  the  atmosphere, 

and  the  heights  of  the  barometer  and  thermometer  at  the  period  of  the 
earthquake. 


Intelligence  and  Miscellaneous  Articles.  157 

It  appears  that  the  analyses  of  Varrentrapp  only,  give  iron  as  pre- 
sent in  these  substances,  and  which  is  essential  to  the  production 
of  the  blue  colour  of  ultramarine :  lapis  lazuli  is  well  known  to  con- 
tain iron  pyrites. 

M.  Eisner  has  analysed  the  blue  and  green  varieties  of  ultramarine 
from  Nuremberg,  and  he  found  them  to  be  composed  as  follows  : — 
Blue  Ultramarine.  Green  Ultramarine. 

Silica 40-0         39'9 

Alumina   29*5         30-0 

Soda 23-0         25-5 

Sulphuric  acid ....       3*4         "4 

Sulphur    4-0         . : 4'6 

Peroxide  of  iron  . .        1*0         '9 

100-9  101-3 

These  contained  traces  of  chlorine,  potash,  lime  and  magnesia.  These 
analyses  show  that  there  is  much  more  sulphur  present  than  is  re- 
quired for  the  production  of  a  simple  sulphuret  of  iron ;  this  excess 
of  sulphur  can  be  combined  only  with  the  sodium ;  and  it  results 
also  from  the  analysis,  as  is^also  shown  by  synthetical  researches, 
that  sulphuret  of  sodium  is  not  less  necessary  than  sulphuret  of  iron 
to  the  production  of  ultramarine. — Journal  de  Pharm.  et  de  Chim., 
Avril  1842.  

PREPARATION  OF  OXICHLORIC  ACID.   BY  M.  AD.NATIVELLE. 

Oxichloric  acid,  which  is  so  useful  as  a  reagent,  M.  Nativelle  re- 
marks, is  seldom  to  be  found  in  laboratories  ;  and  he  supposes  this 
to  be  owing  to  the  small  quantity  of  it  which  is  obtained  by  em- 
ploying the  proportion  of  sulphuric  acid  usually  recommended  in 
chemical  works  :  he  gives  the  following  process  as  separating  the 
whole  of  the  acid  from  the  oxichlorate  of  potash  : — 

Put  into  a  glass  retort  500  parts  of  oxichlorate  of  potash  reduced 
to  powder,  deprived  as  much  as  possible  of  chlorate;  add  1000 
parts  of  sulphuric  acid  of  specific  gravity  1*845,  and  100  parts  of 
distilled  water ;  this  small  quantity  of  water  is  not  indispensable,  for 
it  will  be  shown  that,  by  omitting  it,  oxichloric  acid  is  obtained  in 
the  crystalline  state.  An  adopter  with  a  long  tube  is  to  be  passed 
into  a  tabulated  retort,  surrounded  with  cold  water ;  the  apparatus 
must  not  be  luted  with  any  organic  substance,  for  the  oxichloric 
acid  gas  coming  into  contact  with  it  while  hot  decomposes  it  and 
produces  slight  detonations  ;  when  proper  vessels  are  employed  lute 
need  not  be  employed,  but,  when  required,  filaments  of  amianthus 
answer  the  purpose.  The  oxichlorate  is  to  be  carefully  heated ;  it 
readily  dissolves,  and  the  fire  must  be  regulated  so  as  to  prevent  the 
oxichloric  acid  from  carrying  over  with  it  too  much  sulphuric  acid. 
The  best  method  of  regulating  the  operation  is  to  keep  below  the 
boiling  point ;  but  little  sulphuric  acid  goes  over,  for  oxichloric  acid 
volatilizes  at  284°,  which  is  much  lower  than  the  temperature  at 
which  sulphuric  acid  distils.  The  operation  is  complete  when  the 
residue  in  the  retort  is  transparent  and  colourless,  or  when  the  pro- 
duct drops  very  slowly  and  the  temperature  of  the  retort  is  nearly 
sufficient  to  volatilize  sulphuric  acid ;  the  weight  of  the  product  de- 


158  Intelligence  and  Miscellaneous  Articles. 

pends  upon  the  quantity  of  sulphuric  acid  carried  over ;  for  hy  a 
carefully  conducted  operation  the  ingredients  mentioned  give  about 
300  parts  of  crude  acid  of  the  density  of  about  1*455  ;  when  the 
operation  has  been  too  quickly  conducted  the  density  and  weight  of 
the  product  is  greater. 

In  order  to  separate  the  sulphuric  acid  and  the  small  quantity  of 
chlorine  which  the  product  contains,  it  is  to  be  shaken  with  a  slight 
excess  of  a  saturated  solution  of  sulphate  of  silver,  and  the  chloride 
of  silver  formed  is  separated  by  nitration;  the  acid  is  then  to  be  put 
into  a  capacious  capsule,  and  artificial  carbonate  of  barytes  added 
till  all  the  sulphuric  acid  is  precipitated,  and  even  till  a  little  oxi- 
chlorate  of  barytes  is  formed.  The  liquor  now  contains  only  oxi- 
chloric  acid,  with  a  little  oxichlorate  of  barytes  and  of  silver,  and  is 
to  be  distilled,  in  the  apparatus  already  described,  with  the  addition 
of  ice,  separating  the  first  product,  which  is  only  water,  and  ascer- 
taining that  the  acid  is  coming  over  by  test  paper.  The  distillation 
is  to  be  carried  on  to  dryness,  but  taking  care  not  to  decompose  the 
oxichlorates  of  barytes  and  silver,  for  then  the  rectified  oxichloric 
acid  might  contain  traces  of  chlorine.  'The  oxichloric  acid  thus  ob- 
tained is  perfectly  pure,  colourless  and  transparent ;  its  specific  gra- 
vity is  between  l-717and  1*800,  and  it  is  oleaginous  like  sulphuric 
acid ;  500  parts  of  oxichlorate  of  potash  yielded  150  parts  of  this 
concentrated  acid. — Journal  de  Pharmacie  et  de  Chimie,  June  1842. 


ON  THE  ACTION  OF  WATER  ON  LEAD.    BY  PROF.  CHRISTISON. 

In  a  second  paper  on  this  subject,  just  published  in  the  Transac- 
tions of  the  Royal  Society  of  Edinburgh  (vol.  xv.  part  2.  p.  271), 
Dr.  Christison  states  the  following  as  the  results  of  his  entire  inves- 
tigation : — 

"  From  the  facts  now  detailed,  together  with  the  results  of  my 
former  inquiries,  the  following  conclusions  may  be  drawn  as  to  the 
employment  of  lead  pipes  for  conducting  water. 

"  1.  Lead  pipes  ought  not  to  be  used  for  the  purpose,  at  least 
where  the  distance  is  considerable,  without  a  careful  chemical  ex- 
amination of  the  water  to  be  transmitted. 

"  2.  The  risk  of  a  dangerous  impregnation  of  lead  is  greatest  in  the 
instance  of  the  purest  waters. 

"  3.  Water  which  tarnishes  polished  lead  when  left  at  rest  upon 
it  in  a  glass  vessel  for  a  few  hours,  cannot  be  safely  transmitted 
through  lead  pipes  without  certain  precautions  *. 

"  4.  Water  which  contains  less  than  about  an  8000th  of  salts  in 
solution,  cannot  be  safely  conducted  in  lead  pipes,  without  certain 
precautions. 

"5.  Even  this  proportion  will  prove  insufficient  to  prevent  cor- 
rosion, unless  a  considerable  part  of  the  saline  matter  consist  of  car- 
bonates and  sulphates,  especially  the  former. 

"  G.  So  large  a  proportion  as  a  4000th,  probably  even  a  consider- 

*  "  Conversely,  it  is  probable,  though  not  yet  proved,  that,  if  polished 
lead  remain  untarnished  or  nearly  so  for  twenty-four  hours  in  a  glass  of 
water,  the  water  may  be  safely  conducted  through  lead  pipes.'-' 


Meteorological  Observations.  159 

ably  larger  proportion,  will  be  insufficient,  if  the  salts  in  solution  be 
in  a  great  measure  muriates. 

"7.  It  is,  I  conceive,  right  to  add,  that  in  all  cases,  even  though 
the  composition  of  the  water  seems  to  bring  it  within  the  conditions 
of  safety  now  stated,  an  attentive  examination  should  be  made  of 
the  water  after  it  has  been  running  for  a  few  days  through  the  pipes. 
For  it  is  not  improbable  that  other  circumstances,  besides  those 
hitherto  ascertained,  may  regulate  the  preventive  influence  of  the 
neutral  salts. 

"  8.  When  the  water  is  judged  of  a  kind  which  is  likely  to  attack 
lead  pipes,  or  when  it  actually  flows  through  them  impregnated  with 
lead,  a  remedy  may  be  found  either  in  leaving  the  pipes  full  of  the 
water  and  at  rest  for  three  or  four  months,  or  by  substituting  for 
the  water  a  weak  solution  of  phosphate  of  soda  in  the  proportion  of 
about  a  25,000th  part." 

apothecaries'  hall. 
On  Thursday,  June  23rd,  Mr.  Robert  Warington,  Secretary  to 
the  Chemical  Society,  and  formerly  assistant  to  the  late  Dr.  Edward 
Turner,  Professor  of  Chemistry  in  University  College,  London,  was 
elected  Chemical  Operator  in  this  establishment,  in  consequence  of 
the  recent  lamented  decease  of  Mr.  Henry  Hennell,  F.R.S. 


METEOROLOGICAL  OBSERVATIONS  FOR  JUNE  1842. 

Chiswick. — June] — 3.  Very  fine.  4 — 7.  Hot  and  dry.  8 — II.  Fine:  hot 
and  dry:  clear  at  night.  12,  13.  Clear  and  hot,  thermometer  as  high  as  90°  in 
shade.  14.  Hot  and  dry.  15.  Fine,  with  clouds.  16.  Overcast.  17.  Over- 
cast and  fine.  18.  Heavy  showers.  19.  Very  heavy  rain.  20.  Cloudy  and  fine. 
21.  Slight  rain.  22,  23.  Very  fine.  24.  Slight  rain.  25.  Overcast:  cloudy 
and  windy  :  boisterous,  with  rain  at  night.  26.  Fine  :  cloudy  :  clear,  with  dry 
air  at  night.  27,  28.  Clear  and  fine.  29.  Hot  and  dry.  30.  Slight  rain  :  over- 
cast^:  very  heavy  rain  at  night.  The  mean  temperature  of  the  month  was  20,65 
above  the  average. 

Boston. — June  1.  Cloudy.  2,  3.  Fine.  4.  Fine :  thermometer  76°  two  o'clock 
p.m.  5.  Fine :  rain  with  thunder  and  lightning  p.m.  6 — 8.  Fine.  9.  Cloudy. 
10 — 12.  Fine.  13.  Cloudy.  14.  Fine  :  thermometer  77°  eleven  o'clock  a.m. 
15.  Fine.  16,17.  Cloudy.  18.  Rain.  19.  Cloudy:  rain  p.m.  20.  Fine: 
rain  p.m.  21.  Cloudy:  rain  with  thunder  and  lightning  p.m.  22,23.  Fine: 
rain  p.m.      24.  Fine.      25.  Windy :  rain  p.m.      26,  27.  Windy.      28.  Cloudy. 

29.  Fine.     30.  Cloudy.     N.B.  The  warmest  June  since  June  1826. 
Sandwich  Manse,  Orkney. — June  1 .   Clear  :  shower.     2.    Cloudy :   clear.      3. 

Cloudy.  4.  Cloudy  :  rain.  5.  Clear.  6—8.  Clear :  fog.  9.  Clear :  fine. 
10.  Cloudy:  fine.  11,  12.  Clear :  fine.  13.  Clear :  damp.  14.  Damp.  15. 
Clear:  rain.  16.  Clear  :  shower.  17.  Sleet :  showers.  18.  Clear.  19.  Clear: 
fine.  20.  Cloudy.  21.  Cloudy  :  damp.  22.  Rain:  clear.  23.  Cloudy: 
thunder.  24.  Clear :  cloudy.  25.  Clear  :  shower.  26.  Damp  :  clear.  27. 
Showers  :  sleet.  28.  Cloudy  :  rain.  29.  Cloudy  :  showers.  30.  Showers  : 
cloudy. 

Applegarth  Manse,  Dumfries-shire. — June  1.  Showery.  2,  3.  Fair  and  fine. 
4.  Fine:  shower  p.m.  5.  Warm  and  showery.  6 — 8.  Fair  and  fine.  9 — 11. 
Fair  and  fine:  droughty.  12.  Fair  and  fine.  13.  Fair  and  fine:  thunder. 
14.  Fair,  but  threatening  change.  15.  Fair  till  p.m.:  a  few  drops.  16.  Fair, 
but  cloudy.  17.  Some  drops  of  rain.  18.  Fair  and  fine.  19.  Shower  early 
a.m.  20.  Showers  and  thunder.  21.  Showers :  warm.  22.  Shower  early  a.m. 
23.  Heavy  rain  p.m.  24.  Frequent  showers.  25.  Heavy  rain.  26.  Showers. 
27.  Showers  :  mackerel  sky.    28.  Rain  all  day.     29.  Showers  a.m.  ;  cleared  up. 

30.  Fine,  but  cloudy. 


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THE 
LONDON,  EDINBURGH  and  DUBLIN 

PHILOSOPHICAL  MAGAZINE 

AND 

JOURNAL  OF  SCIENCE. 


[THIRD  SERIES.] 


SEPTEMBER   1842. 


XXVI.  Chemical  Examination  of  the  Fruit  of  Menisper- 
mum  Cocculus  (Semina  Cocculi  Indici).  By  William 
Francis,  Ph.  Z).* 

lyOTWITHSTANDING  the  numerous  investigations  to 
-*-  which  the  grains  of  this  plant  have  been  submitted,  much 
doubt  still  remains  respecting  the  constitution,  and  even  with 
regard  to  the  existence  of  some  of  the  many  interesting  bodies 
said  to  occur  in  them. 

Boullayf,  to  whom  we  are  indebted  for  the  first  exami- 
nation, found  in  them  a  fatty  oil,  stearine,  yellow  extractive 
colouring  matter,  picrotoxine,—  to  which  he  ascribed  the 
properties  of  an  alkaloid, — menispermic  acid,  vegetable  fibre, 
albumen,  and  several  of  the  inorganic  salts  usually  contained 
in  plants.  They  were  subsequently  investigated  by  Casaseca  J, 
principally  witn  regard  to  the  menispermic  acid  ;  he  showed 
that  no  such  acid  existed  in  them,  a  fact  which  has  been  con- 
firmed by  all  later  researches.  The  same  chemist,  in  con- 
junction with  Lecanu§,  made  the  fatty  bodies  which  occur  in 
this  fruit  the  subject  of  a  distinct  treatise,  which  I  shall 
hereafter  have  occasion  to  notice  more  fully.  Oppermann|| 
and  quite  recently  Regnaultf  have  published  analyses  of  pi- 
crotoxine. 

The  most  complete  memoir  on  these  grains  is  one  published 
by  Peltier  and  Couerbe**.  They  describe  in  it  two  new  alka- 
loids, menispermine  and  paramenispermine,  which  are  said  to 
occur  in  the  shells,  and  a  new  acid,  hypopicrotoxinic  acid,  and 
they  ascribe  to  picrotoxine  acid  properties.     The  manner  in 

*  Communicated  by  the  Author.  f  Bulletin  de  Pharmacie,  vol.  iv. 

:  Ibid,  xiifcme  Annee,  Fev.  1826,  p.  99.     §  Ibid.  Janv.  1826,  p.  55. 

II   Mag.  fur  Pkarmaofe,  xxxv.  p.  233. 

f  Ann.  de  Ckimie et  de  Phys.,\xvm.  p.]57.       **  Ann.der  Pharm.B.x.[).18\. 

Phil.  Mag.  Si  3.  Vol.  21.  No.  137.  Sept.  1842.  M 


162       Mr.  W.  Francis's  Chemical  Examination  of  the 

which  they  arrived  at  their  conclusions  has  not  merely  ap- 
peared satisfactory  to  few  chemists,  but  seems  rather  to  have 
created  increased  doubt  with  respect  to  the  true  constituents 
of  these  grains. 

Under  these  circumstances  I  was  induced  to  subject  this 
fruit  to  an  entirely  fresh  analysis :  the  results  of  my  investiga- 
tions I  shall  from  time  to  time  communicate,  as  soon  as  they 
are  so  far  advanced  as  to  be  fit  for  publication ;  in  the  present 
memoir  I  shall  treat  of  the  fatty  substances  which  occur  so 
abundantly  in  the  Cocculus  grains. 

I.  The  Fatty  Substances — Stearophanic  Acid. 

The  only  paper  with  which  I  am  acquainted  in  which  these 
substances  aremadethe  subjectof  investigation,  is  theone  above- 
mentioned  by  Casaseca  and  Lecanu.  By  treating  the  coarsely 
pounded  grains  with  boiling  water  they  obtained  as  extract  a 
considerable  quantity  of  a  fatty  matter,  impregnated  with  a 
green colouringsubstance  which  reddened  litmus  paper:  treated 
with  strong  boiling  alcohol  a  green  solution  was  obtained  pos- 
sessed of  acid  properties,  and  from  which  on  cooling  were  de- 
posited flocky  masses  of  a  neutral  fat  of  a  white  colour.  On 
evaporating  this  alcoholic  solution  they  obtained  a  fat  sub- 
stance, which  pressed  between  bibulous  paper  afforded  a  nearly 
colourless  adherent  nacreous  mass,  easily  soluble  in  boiling 
alcohol,  but  sparingly  in  cold,  and  which  melted  at  59°. 
From  these  properties  the  authors  regarded  it  as  margaric 
acid. 

The  mass  which  had  been  imbibed  by  the  blotting-paper 
was  extracted  with  alcohol,  which  on  evaporation  left  behind 
an  oily  substance  of  a  deep  green  colour,  which  Casaseca  and 
Lecanu  considered  to  be  oleic  acid.  They  conclude  therefore 
from  their  examination,  that  margaric  and  oleic  acids  occur 
in  an  uncombined  state  in  the  grains  of  Cocculus,  and  more- 
over a  neutral  fat,  probably  analogous  to  stearine. 

From  the  following  experiments,  however,  it  will  be  seen 
that  this  acid,  which  it  is  true  occurs  in  large  quantity  in  a 
free  state  in  these  grains,  is  not  margaric  acid,  but  a  new  acid 
neai'ly  related  to  the  latter  in  its  constitution,  but  widely  dif- 
fering from  it  in  its  properties ;  and  further,  that  this  acid 
likewise  occurs  combined  with  the  oxide  of  glyceryle,  and 
thus  constitutes  the  neutral  fat  of  Casaseca  and  Lecanu.  For 
this  acid  I  propose  the  name  of  stearophanic  acid,  (from 
cTBup  and  tpulvopai),  on  account  of  its  beautiful  lustre  in  the 
crystallized  state,  and  for  the  neutral  fat  that  of ' stearophanine. 

When  the  coarsely  pounded  grains  are  digested  with  boil- 
ing alcohol  (that  commonly  used  for  spirit-lamps  is  sufficiently 


Fruit  o/'Menispermum  Cocculus.  163 

strong)  and  the  extract  concentrated  by  distilling  off'  the  al- 
cohol, on  cooling,  a  cake  floating  on  the  surface  is  obtained, 
which  consists  of  a  deep  green- coloured  smeary  fat  matter. 
If  the  kernels  after  having  been  removed  from  the  outer  shells 
are  submitted  to  a  similar  treatment,  the  same  fat  mass  is  ob- 
tained, only  with  this  difference,  that  it  is  no  longer  green 
but  of  a  yellowish  colour,  proving  that  the  green  colouring 
matter  is  only  contained  in  the  outer  shells.  The  fat  mass 
was  separated  from  the  remainder  of  the  extract  and  boiled 
several  times  with  distilled  water,  to  remove  all  traces  of  pi- 
crotoxine  and  other  soluble  substances.  It  possessed  an  acid 
reaction,  and  was  easily  saponified  by  boiling  with  a  dilute 
solution  of  caustic  potash.  The  soap,  which  was  separated 
by  common  salt,  is  hard,  of  a  green  colour,  and  affords 
after  decomposition  by  an  acid  a  green  mass  which  solidifies 
on  cooling.  It  is  very  easily  soluble  in  weak  boiling  alcohol ; 
on  cooling,  a  portion,  which  however  is  still  of  a  yellow  co- 
lour, crystallizes,  the  solution  remaining  green.  The  solid 
acid  thus  prepared,  although  recry stall ized  ten  or  twelve  times, 
could  not  be  obtained  white;  it  always  preserved  Jts  yellow 
tint,  which  was  especially  evident  on  its  being  melted.  The 
filtered  alcoholic  liquor  afforded  on  evaporation  a  dark  green 
acid  oily  liquid,  which  could  not  be  obtained  free  either  from 
colouring  matter  or  from  solid  acid. 

If  after  all  the  picrotoxine  and  colouring  matter  have  been 
removed  by  treatment  three  or  four  times  with  boiling  alcohol, 
the  grains  be  now  acted  upon  by  aether  employing  the  gentle 
heat  of  a  sand-bath,  and  the  filtered  aethereal  solution  be 
placed  in  the  cold,  a  shining  white  fat  crystallizes  slowly  out 
of  it  in  arborescent  aggregations.  It  was  obtained  perfectly 
pure  by  dissolving  it  once  or  twice  in  absolute  boiling  alcohol, 
which  takes  up  very  little  of  it,  and  from  which  it  separates 
on  cooling  in  grains  and  flocks ;  it  has  then  a  dull  white  co- 
lour and  a  constant  melting-point. 

Stearophanic  Acid. — The  pure  fat  thus  prepared  was  sapo- 
nified by  a  solution  of  caustic  potash  until  it  formed  a  per- 
fectly clear  jelly,  and  then  treated  by  salt,  the  solid  soap 
dissolved  in  much  water,  and  decomposed  by  hydrochloric 
acid.  It  collects  on  the  surface  as  a  colourless  oil,  which  soon 
solidifies  into  a  white  crystalline  mass.  It  was  now  boiled 
with  distilled  water  till  all  the  hydrochloric  acid  was  removed, 
and  dissolved  in  weak  warm  alcohol  and  filtered  warm.  On 
cooling,  the  acid  separates  in  small  needles,  which  having 
been  dried  by  exposure  to  the  air,  or  by  pressing  between  bi- 
bulous paper,  possess  a  strong  lustre  of  mother-of-pearl.  Its 
melting  point  is  constant  68°  C. ;  on  cooling  it  crystallizes  in 

M  2 


164         Mr.  W.  Francis's  Chemical  Examination  of  the 

stellate  groups  strongly  resembling  some  kinds  of  Wavellite, 
and  has  a  shining  white  colour.  It  may  easily  be  reduced  to 
a  fine  powder;  it  is  very  soluble  in  warm  weak  alcohol,  from 
which  nearly  the  whole  quantity  separates  on  cooling;  the  so- 
lution has  strong  acid  properties. 

The  acid  obtained  in  the  above  manner  is  the  hydrate  ;  the 
anhydrous  acid  has,  according  to  the  analyses  of  several  of  its 
compounds,  the  following  composition : — 

Calculated  for  100. 

35  atoms  Carbon 2654*89  78*57 

68     ...     Hydrogen  424-30  12*55 

3     ...    Oxygen  300*00  8*88 

3379*19  100*00 

The  composition  of  the  hydrated  acid  in  the  state  in  which 
it  is  separated  from  the  salts,  and  likewise  occurs  free  in  the 
kernels,  was  determined  in  the  following  ultimate  analyses  : — 

i.  0*275  grm.  of  the  hydrated  acid  gave  0*757  carbonic  acid, 

and  0*312  water. 
II.  0*294  grm.  of  the  hydrated  acid  gave  0*8054  carbonic 

acid,  and  0*337  water, 
in.  0*224   grm.  of  the  hydrated  acid  gave  0*613   carbonic 

acid,  and  0*252  water, 
iv.  0*331  grm.  of  the  hydrated  acid  gave  0*913  carbonic 

acid,  and  0357  water. 
v.  0*242  grm.  of  the  hydrated  acid  gave  0*667  carbonic  acid, 
and  0*272  water. 
In  No.  i.  the  combustion  was  effected  by  chromate  of  lead, 
in  the  remainder  oxide  of  copper  was  employed.     No.  v.  is 
an  analysis  of  the  hydrated  acid  as  it  occurs  uncombined  in 
the  grains ;  it  was  still  coloured  somewhat  yellow,  but  was 
quite  crystalline,  and  had  the  same  melting-point  as  the  per- 
fectly white  hydrate. 

The  above  numbers  afford  in  100  parts,  — 

I.  II.  III.  iv.  v. 

Carbon 75*71       75*32       75*24       75*84       75*79 

Hydrogen...   12*60       12*73       12*50       11*98       12*49 
Oxygen 11*69       11*95       12*26       12*18       11*72 

100*00     100*00     100*00     100-00     100-00 
These  closely  approach  the  formula  C35  H70  O4. 

In  100  parts. 

35  atoms  Carbon 2654*89  76*04 

70    ...     Hydrogen     ...    436*78  12-51 

4     ...     Oxygen     400-00  11-75 

3491*67  100-00 


Fruit  o/*  Menispermum  Cocculus.  165 

The  acid  therefore  contains  in  the  state  of  hydrate  1  atom 
of  water,  which  is  replaced  in  the  salts  by  one  equivalent  of 
base. 

StearophanateqfSoda. — This  salt  was  prepared  by  digesting 
the  pure  acid  with  an  excess  of  carbonate  of  soda.  On  expo- 
sing it  to  a  gentle  heat  the  carbonic  acid  is  expelled  with  vio- 
lent ebullition,  and  a  perfectly  clear  solution  formed,  which 
was  evaporated  to  dryness  in  the  water-bath.  The  finely 
powdered  mixture  was  then  digested  with  absolute  alcohol, 
which  leaves  the  excess  of  carbonate  of  soda  undissolved  :  a 
perfectly  clear  solution  is  obtained,  which  however  soon  so- 
lidifies into  a  gelatinous  mass,  which,  transferred  to  a  filter  and 
dried  by  exposure  to  the  air  or  between  folds  of  bibulous  paper, 
leaves  behind  a  crystalline  tissue  consisting  of  long  prisms, 
with  a  strong  nacreous  lustre. 

This  compound,  when  treated  with  a  small  quantity  of  water, 
forms  a  stiff  jelly  ;  it  is  decomposed  on  the  addition  of  much 
water  into  an  acid  crystalline  salt,  which  settles  slowly,  and  im- 
parts to  the  liquid  an  opake  appearance. 

Several  stearophanates  may  be  prepared  from  this  salt  by 
double  decomposition. 

Stearophanate  of  Silver. — This  compound  was  prepared  by 
decomposing  a  weak  alcoholic  solution  of  the  preceding  salt 
by  a  perfectly  neutral  solution  of  the  nitrate  of  silver.  The 
precipitate  is  very  bulky,  but  it  soon  settles.  The  white  co- 
lour which  it  at  first  possesses  is  only  of  momentary  duration; 
it  acquires  a  slight  tint  of  brown.  Well  washed  and  dried,  it 
can  be  exposed  to  light  without  undergoing  apparently  any 
further  decomposition.  It  dissolves  easily  in  a  solution  of 
caustic  ammonia. 

i.  1*134  grm.  of  the  salt,  well  dried  at  100°,  left  after  igni- 
tion 0*317  metallic  silver,  corresponding  to  0*3404  oxide  of 
silver. 

ii.  0*379  grain  of  the  salt- gave  0*105  silver,  corresponding 
to  0*1127  of  the  oxide. 

This  gives  in  100  parts, — 


1  atom  Oxide  of  silver.  . 
1  ...  of  Stearophanic  acid 


Calculated. 

Obtained. 
I.            II. 
30*01     29*73 

1451*61      30*05 

3379*19     69*95 

69*99     70*27 

4830*80  10000 

100*00  100*00 

On  burning  with  oxide  of  copper, — 

i.  0*543  grm.  of  the  silver  salt  gave  1*0695  carbonic  acid, 
and  0*433  water. 

ii.  0*4925  grm.  of  the  salt  gave  0*9763  carbonic  acid,  and 
0*393  water. 


I. 

II. 

54-15 

5451 

8*83 

8-86 

7-15 

6-76 

29-87 

29-87 

166         Mr.  W.  Francis's  Chemical  Examination  of  the 

III.  0'259  grm.  of  the  salt  gave  0*205  water,  which  reduced 
to  100  parts,  gives 

According  to  theory. 

III. 

35  at.  Carbon 54-94 

68  ...  Hydrogen  ....       8*78  8-83       886     8*79 

3  ...  Oxygen 6*23 

1  ...  Oxide  of  silver.  .     3005 

10000  100-00  100-00 
Stearophanate  of  the  Oxide  ofJEthyle. — This  salt  is  a  solid, 
brownish-white,  semi-transparent  mass.  It  was  formed  by 
passing  a  stream  of  dried  muriatic  gas  for  several  hours  into  a 
warm  saturated  alcoholic  solution  of  the  acid.  After  some  time 
the  aether  collects  upon  the  surface  as  a  colourless  oily  fluid, 
which  solidifies  on  cooling.  A  portion  still  remaining  in  solu- 
tion is  obtained  on  the  addition  of  water.  To  free  it  from  acid 
it  was  boiled  several  times  with  a  dilute  solution  of  the  carbo- 
nate of  soda,  and  afterwards  with  water.  It  melts  at  32°  C, 
is  very  fragile,  void  of  smell  in  the  cold,  but  on  being  warmed 
acquires  a  slight  fruity  odour.  It  melts  easily  on  the  tongue, 
imparting  to  it  a  sensation  of  cold,  and  has  a  buttery  taste : 
it  is  very  volatile,  but  is  partially  decomposed  on  distillation. 
It  is  decomposed  by  potash  into  the  stearophanate  of  potash 
and  alcohol. 

The  composition  was  ascertained  in  the  following  ultimate 
analyses : — 

i.  0*381  grm.  of  the  aether  gave  1*0668  carbonic  acid,  and 
0-486  water. 

ii.  0*247  grm.  gave  0*6925  carbonic  acid,  and  0*286  water. 
No.  I.  analysis  was  made  with  oxide  of  copper.     For  No. 
ii.  I  am  indebted  to  the  kindness  of  Dr.  Lawrence  Smith  ;  it 
was  made  with  oxide  of  copper  and  chlorate  of  potash. 

i.  n. 

Carbon  .  .     77*01  77*09 

Hydrogen.     12*69  12*85 

Oxygen  .  .     10*30  10'06 

which  agree  with  the  formula  C4  H,0O  +  C35  H6"8  O3. 
39  Carbon  .  .     295840  77*11 

78  Hydrogen.       491*70  12-51 

4  Oxygen  .  .       400-00  10*38 

3850*10 
Stearophanine. — The  mode  of  preparation  has  been  described 
above.  When  the  fat  is  extracted  by  pressing  the  grains  be- 
tween hot  plates,  or  by  means  of  boiling  water,  it  is  always 
contaminated  by  the  free  acids,  colouring  matter,  &c,  from 
which  it  separates  with  great  difficulty.  If,  on  the  contrary,  the 


Fruit  of  Menispermum  Cocculus.  167 

grains  are  first  digested  several  times  with  moderately  strong 
alcohol,  all  the  substances  which  would  otherwise  be  taken  up 
by  the  aether  are  removed,  and  the  fat  alone  remains.  In  warm 
aether  it  is  very  easily  soluble,  from  which  it  crystallizes  on 
cooling  in  dendritic  aggregations.  It  does  not  crystallize  from 
alcohol,  in  which  it  is  but  sparingly  soluble,  but  separates  as 
a  white  powder.  When  perfectly  pure  it  melts  at  from  35°  to 
36°  C,  does  not  crystallize  on  cooling,  but  shrinks  together, 
forming  a  wave-like  rough  surface;  it  cannot  be  reduced  to  a 
powder,  and  strongly  resembles  wax.  It  does  not  saponify 
easily  on  being  boiled  with  dilute  solution  of  potash,  but  im- 
mediately when  melted  with  potash  and  a  small  quantity  of 
water.  It  then  affords,  when  boiled  with  water,  a  clear  solu- 
tion, from  which  acids  separate  the  stearophanic  acid. 

When  subjected  to  dry  distillation  it  afforded  acroleine,  a 
solid  fat  acid  body, and  a  liquid  product,  but  no  sebacic  acid; 
it  therefore  contains  glycerine,  but  is  free  from  oleine. 

Before  burning  it  with  oxide  of  copper  it  was  kept  for  some 
time  in  the  water-bath,  to  freeitfrom  adhering  traces  of  alcohol. 
The  following  numbers  were  obtained : — 

J.  0*329  grm.  of  stearophanine  gave  0*919  carbonic  acid, 
and  0  361  water. 

ii.  0*231  grm.  gave  0*645  carbonic  acid,  and  0*257  water, 
in.  021 3  grm.  gave  0*236  water. 
In  100  we  have 

i.  ii.  in. 

Carbon  .  .     76*81  76*69 

Hydrogen.     12*19  12*36  12*30 

Oxygen  .  .     11*10  10*95 

which  agrees  with  the  formula  C38  H72  O4. 

38  atoms  Carbon.  .  .     2882*45  77*24 

72     ...     Hydrogen  .       449*25  12*04 

4     ...     Oxygen.  .  .       400*00  10*72 

In  the  present  case  the  same  formula  must  be  admitted  for 
the  constitution  of  glycerine  as  was  proposed  by  Mr.  Stenhouse 
in  his  memoir  on  Palmitine*,  and  which  has  likewise  been 
adopted  by  M.  Marsson  for  that  occurring  in  combination 
with  Laurostearic  acid  in  the  bay  berries  f.  According  to 
the  above  analyses,  stearophanine  consists  of 

1  atom  of  Stearophanic  acid     =   C^H^O3 

1       ...      Glycerine =   C3  H4  O 

1       ...       Stearophanine..     =   C38  H72  O4 
However  similar  the  constitution  of  stearophanic  acid  may 
appear  to  that  of  margaric  acid,  there  cannot  be  the  least  doubt 

*  Philosophical  Magazine,  S.  3.  vol.  xviii.  p.  190. 

t  Annalen  der  Chew.,  und  Pharm.,  vol.  xli.  p.  329  ;   see  also  the  present 
Number,  pp.  237,  238. 


168  Mr.  Gulliver's  Contributions  to  the 

as  to  their  distinctness :  margaric  acid  melts  at  60°  C,  the 
margarate  of  the  oxide  of  aethyle  at  22°;  stearophanic  acid, 
on  the  other  hand,  has  its  melting-point  at  68°  C,  and  its 
compound  with  aether  at  32°.  But  this  is  more  effectually 
proved  by  the  splendid  crystallization  of  the  acid  and  of  its 
soda  salt.  When  compared  with  the  very  numerous  pre- 
parations of  fats  and  their  salts  in  the  collections  of  the  Giessen 
laboratory,  they  surpassed  all  in  lustre  and  beauty,  and  by 
the  well-defined  form  of  the  crystals  of  the  soda  salt. 

As  above  stated,  the  acid  occurs  in  a  free  state  in  the  grains, 
but  only  in  small  quantity,  the  greater  part  consists  of  the  oily 
acid ;  it  probably  varies  according  to  the  time  the  grains  have 
been  preserved,  as  is  the  case  with  palmitic  acid.  On  the 
whole  the  fatty  substances  may  probably  constitute  15  per  cent, 
of  the  grains,  of  which  about  a  third  would  consist  of  the 
neutral  fat.  Wittstock  obtained  11*2  per  cent,  of  oily  matter 
by  pressing  the  grains  between  hot  plates. 

A  portion  of  the  oily  mass  was  subjected  to  dry  distil- 
lation, and  the  products  boiled  with  water,  from  which  on 
cooling  a  large  quantity  of  sebacicacid  was  deposited  in  beau- 
tiful needles  with  a  nacrous  lustre,  and  at  the  same  time 
another  fat  acid  separated  on  the  surface,  which  was  probably 
margaric  acid.  This  experiment  proved  the  oily  fat  and  oily 
acid  which  occur  together  with  that  above  described  in  the 
fruit  of  Menispermum  Cocculus,  to  be  oleine  and  oleic  acid, 
since,  according  to  Redtenbacher,  these  alone  afford  sebacic 
acid  on  dry  distillation. 

The  colouring  matter  which  is  peculiar  to  the  shells  could 
not  be  obtained  in  a  stale  fit  for  analysis. 


XXVII.  Contributions  to  the  Minute  Anatomy  of  Animals.  By 
George  Gulliver,  F.R.S.,  fyc.  fyc— No.  III*. 

On  the  Pus-like  Globules  of  the  Blood. 
TN  the  Philosophical  Magazine  for  September  1838,  (S.  3, 
-*■  vol.  xiii.,  p.  193)  I  have  described  the  frequent  occurrence 
of  globules  of  pus  in  the  blood  of  persons  affected  with  various 
severe  inflammatory  and  suppurative  diseases,  and  have  since 
shown  how  the  pale  globules  of  the  blood  of  healthy  mam- 
malia and  birds  differ  from  the  lymph-globules  of  the  same 
animals  (Gerber's  Anatomy,  p.  83  and  84 ;  Appendix  to  the 
same,  p.  19;  and  Philosophical  Magazine  for  June,  1842). 
In  the  present  communication  the  globules  first  mentioned 
will  be  compared  with  the  pale  globules  now  so  well  known 
as  belonging  to  healthy  blood. 

*  Communicated  by  the  Author.  No.  II.  will  be  found  in  our  last  Num- 
ber, p.  107. 


Minute  Anatomy  of  Animals. — No.  III.  169 

In  some  of  my  earlier  observations  these  two  varieties  of 
globules  were  doubtless  confounded ;  and  their  similarity  is 
often  so  close,  that  it  may  well  be  questioned  whether  there 
js  any  essential  difference  between  them  in  many  cases,  al- 
though it  is  difficult  to  avoid  attributing  to  the  effects  of  dis- 
ease the  unusual  abundance  of  pus-like  globules  in  the  blood  of 
patients  labouring  under  numerous  inflammatory  distempers. 

But  it  often  happens  that  the  pale  globules  appearing  in 
diseased  blood  are  manifestly  different  from  those  found  in  the 
blood  during  health.  The  former  are  generally  rather  larger, 
more  irregular  in  size  and  form,  and  not  uncommonly  more 
opake  than  the  latter.  The  globules  occurring  in  disease  too 
often  appear  to  be  tinged,  especially  when  examined  by  lamp- 
light, of  a  red  colour,  like  the  blood-corpuscles  described  by 
Dr.  Barry  as  in  progress  of  change  into  pus-globules. 

Case  1 . — A  mare,  aged  1 9,  was  lame  of  the  hind-leg,  which 
in  three  days  became  prodigiously  swoln ;  there  were  many 
purulent  deposits  beneath  the  integuments,  and  she  had  much 
fever.  Some  blood,  from  the  facial  vein,  was  now  examined, 
and  found  to  contain  an  unusual  number  of  pus-like  globules, 
(fig.  1.  A.)  the  average  diameter  of  which  was  about  2^W*h  °f 
an  English  inch.  They  occurred  for  the  most  part  singly, 
and  occasionally  in  clumps.  When  treated  with  dilute  acetic 
acid  the  globules  exhibited  nuclei,  generally  central  but  some- 
times attached  to  the  circumference  ;  and  the  smaller  particles 
or  molecules  (the  disc-like  objects  of  Dr.  Barry),  of  which  the 
nuclei  were  composed  were  either  closely  connected  together 
or  separated  by  minutely  granular  matter  (fig.  1 .  B.) .  On  the 
fifth  day,  when  the  disease  had  increased,  some  blood  from  a 
cutaneous  vein  of  the  affected  limb  contained  about  half  as 
many  pus-like  globules  as  red  discs ;  the  former  were  most 
commonly  in  clusters,  and  darker-coloured  than  they  were 
two  days  before. 

The  pale  globules  in  the  blood  of  a  healthy  mare,  examined 
at  the  same  time  for  comparison,  were  by  no  means  so  nu- 
merous ;  they  were  more  regular  in  size  and  shape,  almost  all 
between  yj\,(jth  and  2^Votn  °f  an  ,ncn  m  diameter ;  when  sub- 
jected to  the  action  of  dilute  acetic  acid  they  presented  a  nucleus', 
the  molecules  of  which  were  closely  aggregated  together;  the 
globules  appeared  rather  paler  than  those  of  the  diseased 
blood,  and  were  rarely  to  be  seen  in  clumps  (fig.  1.  C). 

Case  2. — A  gelding,  aged  8,  had  the  disease  termed  by 
veterinarians  laminitis,  that  is  to  say,  inflammation  of  the  vas- 
cular laminae  of  the  corion  beneath  the  crust  of  the  hoof. 
The  disease  was  violent;  relief  was  attempted  by  abstracting 
blood  from  the  brachial  vein,  which  became  inflamed,  and 
the  animal  soon  afterwards  died.     In  the  blood  there  was  a 


170      Mr.  Gulliver  on  the  Minute  Anatomy  of  Animals. 

vast  number  of  pale  globules  resembling  pus,  (fig.  2,  A.)  be- 
sides others  of  a  reddish  colour.  The  latter  corpuscles  (fig. 
2,  B.)  appeared  to  be  composed  of  very  delicate  pale  enve- 
lopes including  from  one  to  four  blood-discs,  rarely  five  or 
six,  some  of  which  were  altered  in  shape,  while  others  pre- 
sented nearly  their  usual  size  and  contour.  They  were  not 
spherical,  as  some  of  them  appear  to  be  in  the  figure.  The 
envelopes,  which  seemed  at  first  like  shadows,  were  distinct 
enough  in  different  lights,  even  after  the  addition  of  water  and 
dilute  acetic  acid,  and  were  rendered  very  obvious  by  the  ac- 
tion of  tincture  of  iodine. 


Fig.  1. 


Fig.  2. 


Fig.  1.  Globules  mentioned  in  case  1.  A,  pus-like  globules 
of  blood  from  the  facial  vein ;  two  of  them  are  round, 
another  is  rather  oval,  a  fourth  is  made  up  of  aggregated 
granules,  and  the  remaining  one  is  much  smaller  and  more 
shapeless  than  the  others.  B,  the  same  globules  treated  with 
dilute  acetic  acid.  C,  pale  globules  from  the  blood  of  a  healthy 
mare,  in  one  of  which  the  nucleus  is  shown  by  dilute  acetic 
acid.  D,  blood-discs  or  unchanged  red  particles  from  the 
same  animal  for  comparison. 

Fig.  2.  Corpuscles  described  in  case  2.  A,  pus-like  glo- 
bules of  blood  from  the  digital  vein,  as  they  appeared  without 
addition.  B,  reddish  corpuscles,  of  which  seven  are  here  de- 
picted, from  the  same  blood  ;  four  of  them  contain  what  ap- 
pear to  be  single  blood-discs,  three  of  which  are  variously 
misshapen ;  of  the  three  other  corpuscles  one  includes  two  discs 
seen  on  their  flat  surfaces  and  touching  merely  at  the  mar- 
gins, another  has  four  slightly  overlapping  at  the  edges,  and 
the  remaining  one  incloses  a  pile  of  similar  discs  seen  on  their 
edges  and  with  their  flat  surfaces  together.  Compare  these 
discs  with  the  unchanged  red  particles  at  D  in  fig.  \ . 

All  the  objects  in  both  figures  are  magnified  exactly  to  the 
same  degree,  namely,  about  800  diameters.     Compare  the  nu- 


On  the  Preparation  of  Quina  and  Cinchonia.  171 

clei  at  B  and  C  in  fig.  1,  with  those  of  the  lymph  and  chyle 
globules,  which  I  have  depicted  in  Gerber's  Anatomy. 

Structure  of  Fibrine. 

In  the  section  on  this  subject  in  the  last  Number  of  the  Phi- 
losophical Magazine,  p.  109-111,  it  should  have  been  stated 
that  in  many  fibrinous  exudations  or  false  membranes,  result- 
ing from  inflammation,  the  structure  is  the  same  as  that  of 
fibrine,  coagulated  either  after  removal  from  the  body  or 
within  the  circulating  channels  simply  from  death.  In  false 
membranes  the  fibrils  are  often  very  distinct :  they  form  a  de- 
licate net-work,  which  incloses  exudation  corpuscles,  much 
resembling  the  organic  germs  before  described  in  pale  clots  of 
fibrine  formed  without  inflammatory  action.  As  these  fibrils 
in  both  instances  appear  to  be  formed  in  the  act  of  coagula- 
tion, it  would  require  some  modification  of  or  departure  from 
the  theory  of  M.  Schwann  to  explain  their  origin. 

Tubercle. 
It  has  long  been  a  question  whether  tubercular  matter  in 
the  lungs  be  situated  in  the  cellular  (filamentous)  tissue  out- 
side the  air-cells,  or  at  the  surface  of  the  mucous  membrane 
within  these  cells.  It  may  be  merely  mentioned  that  I  have 
clearly  detected  tubercular  deposit  in  the  latter  situation  ;  and 
that  Dr.  Willis,  in  his  forthcoming  English  version  of  Prof. 
Wagner's  Physiology,  will  give  an  engraving  of  tubercular 
matter  within  the  air-cells.  This  of  course  will  not  decide 
what  is  always  the  case  in  tubercular  consumption ;  but  it  seems 
to  be  a  fact  of  interest  in  regard  to  the  precise  seat  of  tubercle 
of  the  lungs. 

XXVIII.     On   the   Preparation   of  Quina  and  Cinchonia. 

By  M.  F.  C.  Calvert,  Preparateur  du  Cours  de  Chimie 

appliquee  au  Jardin  des  Plantes  a  Paris. 

To  the  Editors  of  the  Philosophical  Magazine  and  Journal. 
Gentlemen, 
\  LLOW  me,  through  the  medium  of  your  widely-circulated 
■**•  Journal,  to  make  public  a  new  chemical  fact  discovered 
by  me  relating  to  the  extraction  of  quina  and  cinchonia  from 
cinchona  bark,  by  the  knowledge  of  which,  I  believe,  the  pro- 
cess usually  followed  by  the  manufacturers  of  these  alkaloids 
may  be  considerably  improved. 

In  order  to  obviate  some  of  the  difficulties  which  have  hi- 
therto been  experienced  in  extracting  the  alkaline  bases  of 
cinchonia,  it  appeared  to  me  desirable  to  discover  a  process 
by  which,  from  a  certain  quantity  of  cinchona  bark,  all  the 
quina  and  cinchonia  contained  in  it  might  be  extracted.     In 


172     M .  Calvert  on  the  Preparation  of  Quina  and  Cinchonia. 

the  French  manufactories,  and  probably  also  in  the  English, 
the  same  quantity  of  these  bases  has  never  been  extracted  with 
any  regularity  from  equal  weights  of  cinchona  even  of  similar 
quality  :  this  irregularity  will,  I  think,  admit  of  easy  explana- 
tion from  the  fact  which  I  have  ascertained,  that  quiha  is  very 
soluble  in  lime  water  and  in  the  solution  of  chloride  of  calcium; 
hence,  when  lime  is  employed  to  precipitate  those  bases  from 
their  solution  in  the  hydrochloric  acid,  which  is  used  to  extract 
them  from  cinchona  bark,  a  part  of  the  quina  is  re-dissolved, 
especially  should  the  lime  be  added  in  excess  even  in  the 
smallest  quantity.  It  is  true  that  the  re-solution  of  the  quina 
depends  in  great  measure  on  an  excess  of  lime  being  added ; 
but  at  the  same  time  it  must  be  admitted,  that  even  should 
the  greatest  care  be  taken  by  the  manufacturer  to  guard  against 
adding  an  excess  of  lime,  it  would  be  impossible  wholly  to 
prevent  the  solution  of  some  of  the  quina,  as  chloride  of  cal- 
cium will  inevitably  be  formed,  and  consequently  a  part  of  the 
quina  will  be  dissolved  in  it. 

Considering  that  such  must  be  the  unavoidable  result  of  the 
process  usually  followed,  and  reflecting  on  the  serious,  if  not 
insurmountable  obstacle  which  the  re-solution  offers  to  the 
economical  manufacture  of  those  important  articles,  I  was  led 
to  inquire  by  experiments  whether  some  other  and  less  objec- 
tionable means  could  be  discovered  of  precipitating  those  sub- 
stances. 

I  first  experimented  with  solutions  of  caustic  ammonia  and 
potash,  and  soon  found  that  the  use  of  these  alkalies  was  lia- 
ble to  the  same  objection  as  that  of  the  chloride  of  calcium 
and  hydrate  of  lime,  viz.  of  dissolving  a  portion  of  the  qui- 
na when  added  in  excess.  But  the  result  was  found  to  be 
very  different  when  a  solution  of  caustic  soda  was  employed, 
as  this  alkali,  even  when  added  in  excess,  dissolves  neither 
quina  nor  cinchonia.  Of  this  insolubility  I  satisfied  myself 
by  the  following  experiment. 

I  precipitated  a  mixed  solution  of  the  sulphates  of  quina 
and  cinchonia  by  caustic  soda,  and  afterwards  filtered  it; 
the  filtered  liquor  was  next  divided  in  two  equal  parts,  one 
of  these  treated  for  the  purpose  of  ascertaining  whether  any 
quina  had  been  re-dissolved  by  the  soda ;  with  this  object 
in  view,  I  saturated  the  excess  of  alkali  with  hydrochloric 
acid,  and  then  poured  chlorine  into  the  neutral  solution  and 
afterwards  ammonia.  It  is  well  known  that  if  there  had  been 
a  trace  of  quina  or  any  one  of  its  salts  in  the  solution,  a 
green  colour  would  have  been  produced*;  but  in  my  experi- 
ment not  the  slightest  colour  was  observed. 

*  Vide  Journal  Hcbdomadairc  dc  Pharmacic  (vol.  xxii.  p.  37).  Published 
by  M.  Adrien  of  L}ons. 


M.  Calvert  on  the  Preparation  o/Quina  and  Cinchonia.    173 

I  repeated  this  experiment  several  times  both  with  the  sul- 
phuric and  hydrochloric  acids,  and  the  result  being  always 
similar,  I  concluded  that  all  the  quina  had  been  precipitated 
and  none  re-dissolved. 

To  the  other  portion  of  the  filtered  and  alkaline  liquor, 
after  having  saturated  it  with  hydrochloric  acid,  I  applied 
chloride  of  lime,  which  is  a  very  sensible  test  of  the  presence 
ofcinchonia(aswill  be  made  to  appear  presently),  and  having 
obtained  no  precipitate,  I  felt  satisfied  from  this  experiment 
that  no  particle  either  of  quina  or  cinchonia  had  been  re-dis- 
solved :  I  therefore  concluded,  from  the  result  of  these  ex- 
periments, that  the  process  of  extracting  those  two  vegeto- 
alkalies  by  lime  is  imperfect,  and  I  propose,  instead  of  em- 
ploying hydrate  of  lime  for  the  purpose  of  precipitating  the 
alkaline  bases  of  cinchonia,  that  caustic  soda  should  be  used, 
because,  by  employing  it,  all  the  cinchonia,  and  especially 
the  quina,  which  may  be  contained  in  the  acid  liquors,  will 
certainly  be  precipitated  ; — an  object  of  great  importance  to 
those  who  are  engaged  in  this  branch  of  manufacture. 

I  afterwards  endeavoured  to  discover  a  method  by  which 
the  quantity  of  cinchonia  contained  in  sulphate  of  quina 
might  be  easily  ascertained,  as  the  adulteration  of  the  latter 
by  the  addition  of  the  former  is  a  fraud  frequently  practised 
in  commerce,  and  one  which  is  with  difficulty  detected  by  the 
chemical  means  usually  applied.  For  this  purpose  it  has  been 
considered  necessary  to  have  recourse  to  a  complicated  ana- 
lysis, especially  should  it  be  wished  to  ascertain  the  exact 
extent  of  the  adulteration.  As  in  many  works  on  chemistry 
it  is  directed  to  treat  the  solution  of  those  salts  with  an  al- 
kali, by  which  their  bases  are  precipitated,  to  wash  the  pre- 
cipitate, and  then  treat  it  with  aether,  which  dissolves  the 
quina  and  not  the  cinchonia,  I  must  here  take  the  liberty  of 
remarking,  that  should  such  an  analysis  be  undertaken,  it  will 
be  necessary  to  guard  against  using  ammonia  or  potash,  as  a 
small  excess  of  these  alkalies  will  re-dissolve  a  part  of  the  qui- 
na ;  but,  on  the  contrary,  by  employing  soda  this  source  of 
error  is  avoided,  no  quina  being  re-dissolved. 

It  is  true  that  the  end  proposed  can  be  compassed  by  fol- 
lowing the  directions  indicated  in  many  works  on  chemistry, 
and  using  the  precautions  recommended  in  the  concluding 
part  of  the  last  paragraph.  But  it  appeared  to  me  that  it 
would  be  advantageous  to  employ  tests  by  which  the  fraud  in 
question  could  be  more  easily  discovered,  and  I  succeeded  by 
the  application  of  the  six  following  reagents,  and  especially 
the  chloride  of  lime. 

I  saturated  two  portions  of  cold  water,  one  with  very  pure 


174    M.  Calvert  on  the  Preparation  of  Quina  and  Cinchonia. 

sulphate  of  quina,  and  the  other  with  very  pure  sulphate  of 
cinchonia;  I  found  that  10  grammes  of  water  contained  0'033 
of  sulphate  of  quina,  and  that  the  same  quantity  of  water 
contained  0'165of  the  sulphate  of  cinchonia,  or  five  times  the 
proportion  of  sulphate  of  quina ;  therefore,  in  order  to  act  on 
the  same  quantities  of  each  salt  dissolved  in  the  same  quantity 
of  water,  I  took  10  grammes  of  the  solution  of  sulphate  of 
quina,  or  0*033,  and  only  2  grammes  of  the  saturated  solu- 
tion of  sulphate  of  cinchonia,  and  to  this  latter  solution  I 
added  8  grammes  of  water,  and  thus  in  both  cases  I  acted  on 
0*033  of  solid  salt  in  10  grammes  of  water. 

1st.  The  solution  of  the  sulphate  of  quina  gave  a  preci- 
pitate with  chloride  of  lime,  which  was  immediately  re-dis- 
solved by  the  addition  of  an  excess  of  the  reagent. 

The  solution  of  the  sulphate  of  cinchonia,  on  the  contrary, 
gave  a  precipitate  which  was  not  re-dissolved  on  the  addition 
of  even  a  large  excess  of  the  reagent. 

I  afterwards  mixed  the  solutions  of  the  sulphates  of  quina 
and  cinchonia  in  equal  quantities,  and  poured  into  the  mix- 
ture chloride  of  lime;  a  precipitate  was  formed,  of  which  one 
half  was  re-dissolved  on  the  reagent  being  added  in  excess ; 
the  precipitate  which  was  re-dissolved  was  quina:  hence  it 
appears,  that  sulphate  of  quina,  mixed  with  an  equal  quantity 
of  sulphate  of  cinchonia,  could  be  separated  from  it,  and  the 
quantity  of  cinchonia  ascertained^ 

I  next  experimented  on  a  mixture  containing  two  parts  of 
sulphate  of  quina  and  one  of  sulphate  of  cinchonia,  and  a 
similar  result  was  obtained;  that  is,  a  precipitate  was  produced 
on  the  addition  of  chloride  of  lime,  a  portion  of  which,  equal  to 
the  proportion  of  sulphate  of  quina,  was  again  re-dissolved 
on  the  reagent  being  added  in  excess. 

When  the  small  quantity  of  sulphate  of  cinchonia  upon 
which  I  experimented  is  considered,  it  will  be  perceived  how 
easily,  by  means  of  these  reagents,  any  adulteration  of  the 
sulphate  of  quina  by  sulphate  of  cinchonia  may  be  de- 
tected, and  the  smallest  quantity  of  the  substance  discovered, 
as  quina  has  no  influence  on  the  result  of  the  experiment, 
provided  the  liquor  is  sufficiently  diluted  to  guard  against  the 
precipitation  of  sulphate  of  lime. 

In  applying  the  tests  the  greatest  care  was  taken  to  pre- 
vent the  precipitation  of  the  sulphate  of  lime ;  and  the  best 
proof  that  can  be  adduced  of  this  source  of  error  having  been 
avoided  was,  that  if  the  precipitate  had  been  sulphate  of  lime, 
it  would  not  have  disappeared  in  the  experiment  made  with 
the  pure  solution  of  sulphate  of  quina,  and  remained  in  that 
of  the  sulphate  of  cinchonia. 


M.  Calvert  on  the  Preparation  of  Quina  and  Cinchonia.    1 75 

The  following  experiment  will  demonstrate  in  a  manner 
perhaps  still  more  evident,  the  non-formation  of  the  sulphate 
of  lime,  and  will  besides  show  how  very  sensible  a  test  the 
chloride  of  lime  is  to  detect  the  presence  of  cinchonia. 

I  took  2  grammes  of  the  solution  of  sulphate  of  cinchonia, 
containing  0*033,  and  diluted  it  with  48  grammes  of  water, 
and  had  therefore  33  parts  of  this  substance  diffused  in 
50,000  parts  of  water ;  to  this  solution  I  added  a  little  chlo- 
ride of  lime,  and  obtained  a  precipitate  of  cinchonia,  whereby 
the  sensibility  of  the  chloride  of  lime,  as  a  test  of  cinchonia, 
as  well  as  the  non-precipitation  of  sulphate  of  lime,  was  de- 
monstrated; for  the  sulphate  of  lime  formed  in  the  experi- 
ment must  have  dissolved  in  the  very  dilute  solution  of  cin- 
chonia which  was  employed,  and  consequently  the  precipitate 
which  appeared  could  not  be  attributed  to  it. 

The  experiment  was  tried  with  even  double  the  quantity  of 
water,  that  is,  with  33  parts  of  sulphate  of  cinchonia  to 
100,000  parts  of  water;  but  in  this  case  the  precipitate  was 
scarcely  perceptible. 

2nd.  The  chloride  of  calcium  does  not  precipitate  a  sul- 
phate of  quina,  but  it  produces  a  precipitate  with  a  sulphate  of 
cinchonia. 

3rd.  The  sulphate  of  quina  gives  a  precipitate  with  lime- 
water,  but  it  disappears  by  an  excess  of  the  reagent  being 
added ;  while,  on  the  other  hand,  the  sulphate  of  cinchonia 
gives  a  precipitate  which  remains  even  on  the  addition  of  an 
excess  of  the  reagent. 

4th.  The  sulphate  of  quina  gives  a  precipitate  with  am- 
monia, which  disappears  on  the  addition  of  it  in  excess; 
whereas,  in  the  case  of  the  sulphate  of  cinchonia,  a  precipi- 
tate is  produced  which  does  not  disappear  on  adding  a  large 
excess  of  ammonia. 

5th.  The  carbonate  of  ammonia  acts  in  precisely  the  same 
way  as  ammonia. 

6th.  With  potash,  a  precipitate  is  produced  with  sulphate 
of  quina,  but  it  re-dissolves  almost  entirely  when  the  potash 
is  added  in  excess;  while  with  a  sulphate  of  cinchonia  it 
yields  a  curdy-white  precipitate,  which  is  insoluble  in  an  ex- 
cess of  the  reagent. 

7th.  Soda  precipitates  the  bases  of  both  these  salts,  and  the 
precipitate  does  not  re-dissolve  on  the  addition  of  an  excess ; 
there  is,  however,  this  difference  between  the  precipitate  from 
these  two  salts;  that  from  the  sulphate  of  quina  is  pulveru- 
lent, while  that  from  the  sulphate  of  cinchonia  is  curdy- 
white. 

By  means  of  the  first  six  tests,  it  will  always  be  easy  to  di- 


176       Dr.  Booth  on  a  Theorem  in  Analytic  Geometry. 

stinguish  between  quina  and  cinchonia,  and,  judging  from 
the  results  of  my  experiments,  a  mixture  of  those  two  salts 
can  be  detected  ;  but  chloride  of  lime  in  particular  is  the  most 
sensible  test  of  the  presence  of  cinchonia,  and  it  therefore  is 
the  reagent  which  should  be  employed,  when  this  base  is 
mixed  in  small  proportion  with  quina  or  any  of  its  salts. 
The  results  obtained  by  the  use  of  the  seven  above-mentioned 
tests  fully  confirm  all  that  has  been  said  in  speaking  of  the 
extraction  of  these  alkaloids,  and  of  their  quantitative  analysis 
when  mixed  together. 

The  sulphate  of  quina  treated  with  the  chloride  of  plati- 
num gives  a  white  pulverulent  precipitate.  The  sulphate  of 
quina,  treated  with  the  same  reagent,  gives  a  curdy-white 
precipitate. 

The  sulphate  of  quina,  treated  by  the  red  ferro-cyanide  of 
potassium,  gives  a  precipitate  which  disappears  in  an  excess 
of  the  reagent ;  the  liquor  assumes  a  greenish-brown  colour, 
and  ammonia  does  not  change  it  nor  produce  any  precipi- 
tate. 

The  sulphate  of  cinchonia,  submitted  to  the  same  reagent, 
gives  a  precipitate  less  deeply  coloured  than  the  preceding;  it 
is  equally  soluble  in  an  excess,  but  ammonia  re-produces  the 
precipitate  and  destroys  the  colour  in  great  part. 

I  have  likewise  performed  experiments  with  the  following 
substances,  namely,  bichloride  of  mercury,  chloride  of  nickel 
and  cobalt,  the  iodide  of  potassium,  and  solution  of  iodine, 
but  they  offer  no  distinctive  characters. 

I  will  only  repeat  in  conclusion,  first,  that  in  the  preparation 
of  quina  and  cinchonia,  lime  should  be  replaced  by  soda: 
carbonate  of  potash  or  soda  may  be  employed,  but  they  have 
the  inconvenience  of  dissolving  part  of  the  cinchonia ;  se- 
condly, that  in  case  of  a  quantitative  analysis  being  under- 
taken, the  same  alkali  alone  should  be  employed  to  precipitate 
those  bodies ;  and  thirdly,  that  in  case  of  sulphate  of  quina 
being  supposed  to  be  adulterated  with  the  sulphate  of  cincho- 
nia, and  that  it  may  be  wished  to  ascertain  the  extent  of  adul- 
teration, the  tests  upon  which  reliance  can  be  placed,  are,  first, 
chloride  of  lime ;  secondly,  chloride  of  calcium;  thirdly,  lime- 
water;  and  fourthly,  ammonia  and  carbonate  of  ammonia. 

XXIX.    On  a  Theorem  in  Analytic  Geometry.     By  James 
Booth,  Esq.,  LL.D.,  M.R.I.A* 

IT  has  been  justly  remarked  by  an  author  who  has  himself 
largely  contributed  to  the  advance  of  mathematical  science, 
*  Communicated  by  the  Author. 


Dr.  Booth  on  a  Theorem  in  A?iatytic  Geometry.        177 

"  qu'on  sert  peut-etre  plus  encore  la  science  en  simplifiant,  de 
la  sorte,  des  theories  deja  connues,  qu'en  l'enrichissant  de 
theories  nouvelles,  et  c'est  la  un  sujet  auquel  on  ne  saurait 
s'appliquer  avec  trop  de  soin." — Annates  de  Mathematiques, 
torn.  xix.  p.  338. 

Extending  this  remark  to  the  simplification  of  the  methods 
of  establishing  theorems  already  known,  and  remarkable  for 
their  difficulty,  I  am  induced  to  give  an  exceedingly  simple 
demonstration  of  a  theorem,  which  may  be  found  at  p.  342  of 
Dupin's  Developpements  de  Geometrie,  where  the  accomplished 
author  bestows  more  than  four  quarto  pages  of  analytical  cal- 
culation of  extreme  complexity  on  this  theorem,  and  yet  leaves 
its  solution  incomplete. 

The  following  is  the  theorem  to  which  I  allude: — 

Three  points  assumed  on  a  right  line  are  always  retained  in 
three  fixed  planes,  any  fourth  point  P  in  this  right  line  will  de- 
scribe an  ellipsoid,  whose  centre  is  the  common  intersection  of 
the  three  fixed  planes. 

Let  O  x,  O  y,  O  z,  be  the 
intersections  of  the  three  fixed 
planes,  Ox,  O  y,  Oz  being 
the  axes  of  coordinates,  and 
C  P  the  moving  right  line  in 
any  position,  meeting  the  plane 
of  O  x  y  in  the  assumed  point 
C ;  let  the  distances  of  P  to  the 
points  in  the  planes  of  x  y,  y  z, 
z  x  be  c,  a,b;  and  let  the  an- 
gles between  the  axes  of  x  and 
y,yz,  andz  x  be  v,  A,  jo.;  through 
P  let  three  right  lines  be  drawn 
P  m,  Pn,  P  r,  parallel  to  the 
lines  O  x,  Oy,  O  * ;  in  the  line 
P  C  assume  the  point  Q,  so  that  P  Q  =  8,  and  complete  the 
parallelopiped  of  which  P  Q  is  the  diagonal ;  let  the  sides  of 
this  parallelopiped  parallel  to  the  axes  O  x,  O  y,  O  z  be  «,  |3,  y, 
then  we  shall  have  by  a  well-known  theorem,  given  in  most 
elementary  works  on  the  subject*,  which  expresses  the  relation 
between  the  diagonal  sides  and  contained  angles  of  a  paralle- 
lopiped. 


a2  +  ^  +  y2  +  2  /3  y  cos  A  +  2  a  y  cos  p.  +  2  a  |3  cos  v 
or  dividing  by  89, 


8»! 


g2  + 


P  .  r9  ,  *lrL-\  ,  «ay  — ..  .  ««£ 


+  -&+  2^  cos  A  +  2-f  cosju,  +  2-^cosv=l  (1.) 


*  See  Legendre's  Geometry,  p.  249  (Brewster's  Edition). 
Phil.  Mag.  S.  3.  Vol.  21.  No.  137.  Sept.  1842.  N 


178        Dr.  Booth  on  a  Theorem  in  Analytic  Geometry. 

Now  the  triangles  PCD,  P  Q  r  are  similar,  hence 

PD:PC::Pr:PQ,  orZ:C::y:8,  hence 

z        y     •    im  x         u     y         Q 

—  =  4-;  in  like  manner  —  as  -5-,  4-  =  •£-; 

c(>  a         0      0        0 

making  these  substitutions  in  (l.)»  we  find 

a?      y*      z*      „y  z  ,xx  z  „xy  i'tJ.\ 

T  +  72  +  -5  +  2  /  cos  A  +  2  —  Cos  p  +  2  -i  COS  V  =  1  (2.) 
or      o*      cz         be  ac  ab  v    ' 

The  equation  of  an  ellipsoid  whose  centre  is  at  the  origin  when 
the  coordinate  planes  are  rectangular,  the  equation  becomes 
simply 

«2    T     /)*»    +    C2    -    *' 

It  follows  immediately  from  (2.)  that  the  coordinate  planes 
can  never  be  conjugate  planes  of  the  surface,  except  when  rect- 
angular, as  in  no  other  case  do  the  rectangles  vanish. 

To  find  the  coordinates  of  the  point  where  the  tangent  plane 
is  parallel  to  one  of  the  coordinate  planes,  that  of  xy.  Sup- 
pose V  =  0,  being  the  equation  of  the  surface,  the  general 
equation  of  the  tangent  plane  is 

dV ,         ^      d\  .  n       dV  ,  '"'""■ 

^(*-^)  +  ^Q/-y)+^(z-*')  =  0; 

and  when  the  tangent  plane  is  parallel  to  that  of  xy, 
Now 


—  =•  0   —  =  0 

dx  ~    *  dy 


dV       x        y  z 

-j—  — f-  ■—  cos  v  -\ cos  a  =  0, 

dx        a         0  c 

dV       y        x  z 

-r—  =  4-  -1 cos  v  -I cos  a  —  0: 

dy        b        a  c 

from  these  equations,  finding  the  values  of  x  and  y  in  terms 
of  z,  and  substituting  in  (2.),  there  results 

2  /"  1  —  cos2  A  —  COS2  jU.  —  cos2  v  -f  2  cos  X  cos  JO.  cos  v~\     _    2# 
L  sin2  v  J 

the  expression  within  the  brackets  is  the  square  of  the  sine  of 
the  angle  which  the  axis  of  z  makes  with  the  plane  of  xy, 

calling  this  angle  <p,  z  =  - —  ;  now  this  value  of  z  is  evidently 

a  conjugate  diameter  to  the  plane  of  x  y,  since  the  tangent 
plane  is  parallel  to  the  plane  of  x  y ;  hence  whenever  the  ge- 


Dr.  Booth  on  a  Theorem  in  Analytic  Geometry.         179 

nerating  line  is  perpendicular  to  one  of  the  coordinate  planes, 
the  line  drawn  from  the  centre  to  the  point  where  this  line  in- 
tersects the  surface  is  a  conjugate  diameter  to  this  plane,  a 
result  which  might  be  obtained  from  geometrical  considera- 
tions. 

We  may,  as  a  simple  consequence  from  the  preceding  de- 
monstration, obtain  a  theorem  in  spherical  trigonometry  ap- 
parently new. 

Let  a,  b,  c  be  the  sides  of  a  spherical  triangle,  and  P",  P',  P 
the  arcs  of  three  great  circles  drawn  from  the  vertices  A,  B,  C 
of  the  spherical  triangle,  through  a  point  S  assumed  on  the  sur- 
face of  the  sphere  to  the  opposite  sides,  p"  p1  p  the  segments  of 
those  arcs  between  the  point  S  and  the  sides  a,  b,  c,  we  shall 
have 

tsinp       sinp'        sinp"~]*__ 
sm~P  +  shTF  +  suTFj    "" 

Sm^sin^sin^J^(1_cos  ^  SJ^  n 

sinPsinP/sinP"Lsin^v  '       €va.p'y  '  '  s»jr"  J 

To  show  this,  through  the  point  O  let  a  right  line  be  drawn 

parallel  to  P  Q,  meeting  the  surface  of  the  sphere  in  S,  and 

let  the  sides  of  the  spherical  triangle,  opposite  the  angles  A,  /*,  y, 

be  a,b,c;  then  in  the  triangle  PCD:  PD:PC::sinPCD 

:  sin  P  D  C  :  sin  p  :  sin  P. 

Since  P  D  is  parallel  to  O  Z,  and  P  C  parallel  to  O  S, 

,  z        sin  p 

hence  —  =  -. — £. 

c       sin  P 

c.-    -i    i      *        sin»"    y        sinp'        .  .       .  ,     . 

Similarly,  —  =  ^j^,,  -|-  =  ^— ^,;  making  these  substitu- 
tions in  (2.),  after  some  obvious  simplifications  we  find 

tsinj9       siny       sinj9"~l2_ 
imP  +  imP7  +  imF J    ~  ' 

+  Z^^sin/TsinP  (i_ cos  A  +  ^ (1  -cos b)+™L^  (1  _ cos  a)~| 
T   sinPsinP,sinP"Lsini>v  J^sinp,K  '     sin/>"  V  ; J 

When  the  triangle  becomes  plane,  the  sines  are  changed  into 
the  corresponding  arcs,  and  cos  a,  cos  b,  cos  c  are  each  equal 
to  unity,  and  we  thus  derive  the  known  theorem  in  plane  geo- 
metry, 


P    ,   P* 


j  i 


P 


+  p/  +  pw  —  *• 


N2 


[  180  ] 

XXX..  Notes  on  the  Effects  produced  by  the  Ancient  Glaciers 
of  Caernarvonshire,  and  on  the  Boulders  transported  by 
Floating  Ice.  By  Charles  Darwin,  Esq.,  M.A.,  F.R.S. 
and  F.G.S. 

#?j_UIDED  and  taught  by  the  abstract  of  Dr.  Buckland's 
^  memoir  "  On  Diluvio- Glacial  Phaenomena  in  Snowdonia 
and  the  adjacent  parts  of  North  Wales*,"  I  visited  several  of 
the  localities  there  noticed,  and  having  familiarized  myself 
with  some  of  the  appearances  described,  I  have  been  enabled 
to  make  a  few  additional  observations. 

Dr.  Buckland  has  stated  that  a  mile  east  of  Lake  Ogwyn 
there  occurs  a  series  of  mounds,  covered  with  hundreds  of 
large  blocks  of  stone,  which  approach  nearer  to  the  condition 
of  an  undisturbed  moraine,  than  any  other  mounds  of  detritus 
noticed  by  him  in  North  Wales.  By  ascending  these  mounds 
it  is  indeed  easy  to  imagine  that  they  formed  the  north-west- 
ern lateral  moraine  of  a  glacier,  descending  in  a  north-east  line 
from  the  Great  Glyder  mountain.  But  at  the  southern  end 
of  Lake  Idwell  the  phenomena  of  moraines  are  presented, 
though  on  a  much  smaller  scale,  with  perfect  distinctness. 
On  entering  the  wild  amphitheatre  in  which  Lake  Idwell  lies, 
some  small  conical,  irregular  little  mounds,  which  might  easily 
escape  attention,  may  be  seen  at  the  further  end.  The  best 
preserved  mounds  lie  on  the  west  side  of  the  great  black  per- 
pendicular face  of  rock,  forming  the  southern  boundary  of  the 
lake.  They  have  been  intersected  in  many  places  by  streams, 
and  they  are  seen  to  consist  of  earth  and  detritus,  with  great 
blocks  of  rock  on  their  summits.  They  at  first  appear  quite 
irregularly  grouped,  but  to  a  person  ascending  any  one  of 
those  furthest  from  the  precipice,  they  are  at  once  seen  to 
fall  into  three  (with  traces  of  a  fourth)  narrow  straight  linear 
ridges.  The  ridge  nearest  the  precipice  runs  someway  up  the 
mountain,  but  the  outer  one  is  longer  and  more  perfect,  and 
forms  a  trough  with  the  mountain-side,  from  10  to  15  feet  deep. 
On  the  eastern  arid  opposite  side  of  the  head  of  the  lake,  cor- 
responding but  less  developed  mounds  of  detritus  may  be  seen 
running  a  little  way  up  the  mountain.  It  is,  I  think,  impossi- 
ble for  any  one  who  has  read  the  descriptions  of  the  moraines 
bordering  the  existing  glaciers  in  the  Alps;  to  stand  on  these 
mounds  and  for  an  instant  to  doubt  that  they  are  ancient  mo- 
raines ;  nor  is  it  possible  to  conceive  any  other  cause  which 
could  have  abruptly  thrown  up  these  long  narrow  steep  mounds 
of  unstratified  detritus  against  the  mountain-sides.     The  three 

*  Read  before  the  Geological  Society,  December  15th,  1841,  and  the 
Abstract  is  published  in  the  Athenaeum,  1842,  p.  42.  [An  Abstract  of  Dr. 
Buckland's  paper,  from  the  Proceedings  of  the  Society,  will  appear  in  an 
early  number  of  the  Philosophical  Magazine.— Edit.] 


Mr.  Darwin  on  the  Ancient  Glaciers  of  Caernarvonshire.  181 

or  four  linear  ridges  evidently  mark  the  principal  stages  in  the 
retreat  of  the  glacier ;  the  outer  one  is  the  longest,  and  di- 
verges most  from  the  great  wall  of  rock  at  the  south  end  of 
the  lake.  The  inner  lines  distinctly  define  the  boundary  of 
the  glacier  during  the  last  stage  of  its  existence.  At  this  pe- 
riod a  small  and  distinct  glacier  descended  from  a  narrow  but 
lofty  gorge  on  the  north-western  end  of  the  lake ;  and  here 
remnants  of  a  terminal  moraine  may  be  traced  in  the  little 
mounds,  forming  a  broken  semicircle  round  a  rushy  plain, 
scarcely  more  than  a  hundred  yards  in  diameter.  The  rocks 
are  smoothed,  mammillated  and  scored,  all  round  the  lake, 
and  at  some  little  depth  beneath  the  surface  of  the  water,  as  I 
could  both  see  and  feel.  Similar  marks  occur  at  great  heights 
on  all  sides,  far  above  the  limits  of  the  moraines  just  described, 
and  were  produced  at  the  time  when  the  ice  poured  in  a  vast 
stream  over  the  rocky  barrier  bounding  the  northern  end  of 
the  amphitheatre  of  Lake  Idwell. 

I  may  here  mention,  that  about  eighty  yards  west  of  the  spot 
where  the  river  escapes  from  the  lake,  through  a  low  mound 
of  detritus,"  probably  once  a  terminal  moraine,  there  is  an  ex- 
ample of  a  boulder  broken,  as  described  by  Charpentier  and 
Agassiz,  into  pieces,  from  falling  through  a  crevice  in  the  ice. 
The  boulder  now  consists  of  four  great  tabular  masses,  two  of 
which  rest  on  their  edges,  and  two  have  partly  fallen  over 
against  a  neighbouring  boulder.  From  the  distance,  though 
small  in  itself  at  which  the  four  pieces  are  separated  from  each 
other,  they  must  have  been  pitched  into  their  present  position 
with  great  force ;  and  as  the  two  upright  thin  tabular  pieces 
are  placed  transversely  to  the  gentle  slope  on  which  they 
stand,  it  is  scarcely  possible  to  conceive  that  they  could  have 
been  rolled  down  from  the  mountain  behind  them  ;  one  is  led, 
therefore,  to  conclude  that  they  were  dropped  nearly  vertically 
from  a  height  into  their  present  places. 

The  rocky  and  steep  barrier  over  which  the  ice  from  the 
amphitheatre  of  Lake  Idwell  flowed  into  the  valley  of  Nant- 
Francon,  presents  from  its  summit  to  its  very  foot  (between 
400  and  500  feet)  the  most  striking  examples  of  boss  or  dome- 
formed  rocks;  so  much  so,  that  they  might  have  served  as 
models  for  some  of  the  plates  in  Agassiz's  work  on  Glaciers. 
When  two  of  the  bosses  stand  near  and  are  separated  only  by 
a  little  gorge,  their  steep  rounded  sides  are  generally  distinctly 
scored  with  lines,  slightly  dipping  towards  the  great  valley  in 
front.  The  summit  of  the  bosses  is  comparatively  seldom 
scored ;  but  on  one  close  to  the  bridge  over  the  river  Ogwyn, 
I  remarked  some  singular  zigzag  scores.  At  this  spot  the 
cleavage  of  the  slate  is  highly  inclined,  and  owing  apparently 


182  Mr.  Darwin  on  the  Ancient  Glaciers  of  Caernarvonshire, 

to  the  different  degrees  of  hardness  of  the  laminae,  smooth  and 
gentle  furrows  have  been  produced  by  the  grinding  of  the  ice, 
transversely  to  the  scores,  and  to  the  probable  course  of  the 
glacier.  Here,  as  well  as  in  some  few  other  places,  I  noticed 
an  appearance  which  made  it  vividly  clear  that  these  bosses 
had  been  formed  by  some  process  quite  different  from  ordinary 
aqueous  or  atmospheric  erosion ;  it  is  the  abrupt  projection 
from  the  smooth  surface  of  a  boss  of  a  piece  of  rock  a  few  yards 
square,  and  one  or  two  feet  in  height,  with  its  surface  smoothed 
and  scored  like  the  boss  on  which  it  stands,  but  with  its  sides 
jagged :  if  a  statuary  were  to  cut  a  small  figure  out  of  a  larger 
one,  the  abrupt  projecting  portions,  before  he  quite  completed 
his  work,  might  be  compared  to  these  masses  of  rock  :  how  it 
comes  that  the  glacier,  in  grinding  down  a  boss  to  a  smaller 
size,  should  ever  leave  a  small  portion  apparently  untouched, 
I  do  not  understand. 

On  the  summit  of  some  of  the  bosses  on  this  barrier  there 
are  perched  boulders :  but  this  phenomenon  is  seen  far  more 
strikingly  close  to  Capel-Curig,  where  almost  every  dome  of 
rock  south  of  the  Inn  is  surmounted  by  one  or  more  large 
angular  masses  of  foreign  rock.  The  contrast  between  the 
rude  form  of  these  blocks,  and  the  smooth  mammillated  domes 
on  which  they  rest,  struck  me  as  one  of  the  most  remarkable 
effects  produced  by  the  passage  of  the  glaciers.  On  the  sides 
of  the  mountains  above  Capel-Curig,  I  observed  some  bould- 
ers left  sticking  on  very  narrow  shelves  of  rocks,  and  other 
boulders  of  vast  size  scattered  in  groups.  The  largest  boulder 
I  noticed  there  was  about  26  feet  in  length  by  12  in  breadth, 
and  buried  to  an  unknown  thickness. 

Proceeding  down  the  great  straight  valley  of  Nant-Francon, 
which  must  formerly  have  conveyed  the  united  glaciers  from 
Lakes  Idwell  and  Ogwyn,  we  continue  to  meet  with  boss- 
formed  rocks  till  below  the  village  of  Bethesda.  From  this 
point  towards  Bangor  these  boss-formed  rocks  become  rare ; 
at  least  it  is  certain  that  a  large  number  of  hummocks  of  rock 
with  rugged  surfaces  project,  whereas  higher  up  in  this  valley, 
and  in  all  the  great  central  valleys  of  Snowdonia,  such  un- 
ground  hummocks  are  not  to  be  met  with.  At  Bethesda,  un- 
stratified  masses  of  whitish  earth,  from  ten  to  forty  feet  in 
thickness,  full  of  boulders  mostly  rounded,  but  some  angular, 
from  one  to  four  feet  square,  are  first  met  with.  This  deposit 
is  interesting  from  the  boulders  being  deeply  scored,  like  the 
rocks  in  situ  over  which  a  glacier  has  passed.  The  scores  are 
sometimes  irregular  and  crooked,  but  generally  quite  parallel, 
as  I  distinctly  saw  over  the  entire  side  of  one  large  block. 
Some  of  the  blocks  were  scored  only  on  one  side,  others  on 


and  on  Boulders  transported  by  Floating  Ice.         183 

two  sides,  but  from  the  difficulty  of  turning  over  the  larger 
ones,  I  do  not  know  which  case  is  most  common.  I  saw  one 
large  block  on  which  the  scores  on  the  opposite  sides  were 
all  parallel ;  and  another  irregularly  conical  one,  four  feet  in 
length,  of  which  three-fourths  of  the  circumference  was  marked 
with  parallel  striae,  converging  towards  the  apex.  In  the 
smaller  elongated  blocks,  from  six  to  twelve  inches  in  diameter, 
I  observed  that  the  striae  were  generally,  if  not  always,  paral- 
lel to  their  longer  axes,  which  shows  that  when  subjected  to 
the  abrading  force,  they  arranged  themselves  in  lines  of  least 
resistance.  Out  of  three  large  blocks  which  remained  im- 
bedded in  a  perpendicular  cliff,  the  vertical  sides  of  two  were 
scored  in  horizontal  lines,  and  of  the  third  in  an  oblique  di- 
rection. These  several  facts,  especially  the  parallel  striae  on 
the  upper  and  lower  surfaces,  show  that  the  boulders  were  not 
scored  on  the  spot  where  they  are  now  imbedded,  as  seems  to 
have  been  the  case  with  the  boulders  described  by  Mr  Mac- 
laren*  in  the  till  near  Edinburgh.  The  contrast  is  very  stri- 
king in  the  state  of  the  surface  of  these  boulders,  and  those 
which  lie  scattered  high  up  on  the  sides  of  the  adjoining  hills 
and  of  the  great  central  valleys,  or  are  perched  on  the  worn 
bosses  of  naked  rock ;  such  boulders,  as  I  particularly  noticed, 
present  no  signs  of  scores  or  strias,  as  might  have  been  antici- 
pated, if,  as  is  supposed,  they  were  transported  on  the  surface 
of  the  glaciers.  In  the  quarries  which  I  examined,  namely, 
below  Bethesda,  and  at  some  little  height  on  the  eastern  side 
of  the  village,  the  till  rested  on  slate-rocks,  not  worn  into 
bosses.  I  found,  however,  a  rather  smooth  pap  of  greenstone 
marked  with  a  few  deep  scores.  The  till  forms,  at  the  height 
probably  of  600  feet  above  the  sea,  a  little  plain,  sloping  sea- 
ward ;  and  between  Bethesda  and  Bangor,  there  are  other 
gently  inclined  surfaces  composed  of  till  and  stratified  gravel. 
Considering  these  facts,  together  with  the  proofs  of  recent  ele- 
vation of  this  coast,  hereafter  to  be  mentioned,  I  cannot  doubt 
that  this  till  was  accumulated  in  a  sloping  sheet  beneath  the 
waters  of  the  sea.  In  composition  it  resembles  some  of  the 
beds  of  till  in  Tierra  del  Fuego,  which  have  undoubtedly  had 
this  origin.  I  presume  the  scored,  rounded,  and  striated 
boulders  were  pushed,  in  the  form  of  a  terminal  moraine,  into 
the  sea,  by  the  great  glacier  which  descended  Nant-Francon. 

Mr.  Trimmer f  reports,  on  the  authority  of  some  workmen, 

*  Geology  of  Fife  and  the  Lothians,  p.  212. 

t  Proceedings  of  the  Geological  Society,  vol.i.  p.  332,  or  Phil.  Mag.  S. 
2.  vol.  x.  p.  1 43.  Mr.  Trimmer  was  one  of  the  earliest  observers  of  the  scores 
and  other  marks  on  the  rocks  of  North  Wales.  He  has  also  remarked  that 
"some  of  the  larger  blocks  amid  the  gravel  have  deep  scratches  upon  their 
surface."  Mr.  Trimmer  himself  found  broken  sea-shells  in  the  diluvium  at 
Beaumaris. 


184  Mr.  Darwin  on  the  Ancient  Glaciers  of  Caernarvonshire, 

that  sea-shells  have  been  found  on  Moel  Faban,  two  miles 
N.E.  of  Bethesda.  I  ascended  this  and  some  neighbouring 
hills,  but  could  find  no  trace  of  any  deposit  likely  to  include 
shells.  This  hill  stands  isolated,  out  of  the  course  of  the  gla- 
ciers from  the  central  valleys  ;  it  exceeds  1000  feet  in  height; 
its  surface  is  jagged,  and  presents  not  the  smallest  appear- 
ance of  the  passage  of  glaciers :  but  high  up  on  its  flanks  (and 
perhaps  on  its  very  summit)  there  are  large,  angular  and 
rounded  boulders  of  foreign  rocks. 

Along  the  sea-coast  between  Bangor  and  Caernarvon,  and 
on  the  Caernarvonshire  plain,  I  did  not  notice  any  boss-formed 
hillocks  of  rock.  The  whole  country  is  in  most  places  con- 
cealed by  beds  of  till  and  stratified  gravel,  with  scattered 
boulders  on  the  surface:  some  of  these  boulders  were  scored. 
From  the  account  given  by  Mr.  Trimmer*  of  his  remarkable 
discovery  of  broken  fragments  of  Buccinum,  Venus,  Natica, 
and  Turbo,  beneath  twenty  feet  of  sand  and  gravel,  on  Moel 
Tryfan  (S.E.  of  Caernarvon),  I  ascended  this  hill.  Its  height 
is  1192  feetf  above  the  sea;  it  is  strewed  with  boulders  of  fo- 
reign rock,  most  of  them  apparently  from  the  neighbouring 
mountains ;  but  near  the  summit  I  found  the  rounded  chalk- 
flints  X  and  small  pieces  of  white  granite  alluded  to  by  Dr. 
Buckland.  Its  form  is  conical,  and  it  stands  isolated: 
wherever  the  bare  rock  protrudes  its  surface  is  jagged,  and 
shows  no  signs  of  being  in  any  part  worn  into  bosses.  The 
contrast  between  the  superficial  part  of  the  bare  rock  on  this 
hill  and  on  Moel  Faban,  with  that  of  the  rocks  within  the 
great  central  valleys  of  Caernarvonshire,  is  very  remarkable ; 
it  is  a  contrast  of  precisely  the  same  kind  as  may  be  observed 
in  these  same  valleys  by  ascending  on  either  side  above  the 
reach  of  the  ancient  glaciers.  A  little  way  down  the  hill,  a 
bed  two  or  three  feet  in  thickness,  of  broken  fragments  of  slate 
mixed  with  a  few  imperfectly  rounded  pebbles  and  boulders 
of  many  kinds  of  rock,  is  seen  in  several  places  to  rest  on  the 
slate,  the  upper  surface  of  which,  to  the  depth  of  several  feet, 
has  been  disintegrated,  shattered  and  contorted  in  a  very  cu- 
rious manner.  The  laminated  fragments,  however,  sometimes 
partially  retain  their  original  position. 

I  did  not  succeed  in  finding  any  fragments  of  shells,  but 
near  the  summit  of  the  hill  on  the  eastern  or  inland  side,  I 
found  beds,  at  least  twenty  feet  in  thickness,  of  irregularly 
stratified  gravel  and  boulders,  with  distinct  and  quite  defined 
layers  of  coarse  yellow  sand,  and  others  of  a  fine  argillaceous 

•  Proceedings  of  the  Geological  Society,  vol.  i.  p.  332.  [Phil.  Mag.  loc.  cit.] 
t  Murchison's  Silurian  System,  p.  528. 

j  I  may  mention,  that  at  Little  Madely,  in  Staffordshire,  I  have  found 
chalk-flints  in  the  gravel-beds,  associated  with  existing  species  of  sea-shells. 


and  on  Boulders  transported  by  Floating  Ice.         185 

nature  and  reddish  colour.  These  beds  closely  resemble 
those  of  Shropshire  and  Staffordshire,  in  which  are  found  (as 
I  have  myself  observed  in  very  many  places)  fragments  of  sea- 
shells,  and  which  every  one,  I  believe,  since  the  publication 
of  Mr.  Murchison's  chapters  on  the  drift  of  these  counties, 
admits  are  of  submarine  origin.  It  may  therefore  be  con- 
cluded that  the  layers  of  coarse  and  argillaceous  sand,  and  of 
gravel,  with  far- transported  pebbles  and  boulders,  do  not  owe 
their  origin  to  an  inundation,  but  were  deposited  when  the 
summit  of  Moel  Tryfan  stood  submerged  beneath  the  surface 
of  the  sea.  As  there  are  no  marks  of  the  passage  of  glaciers 
over  this  mountain  (which  indeed  from  its  position  could 
hardly  have  happened),  we  must  suppose  that  the  boulders 
were  transported  on  floating  ice ;  and  this  accords  with  the 
remote  origin  of  some  of  the  pebbles,  and  with  the  presence 
of  the  sea-shells.  Within  the  central  valleys  of  Snowdonia, 
the  boulders  appear  to  belong  entirely  to  the  rocks  of  the 
country.  May  we  not  conjecture  that  the  icebergs,  grating 
over  the  surface,  and  being  lifted  up  and  down  by  the  tides, 
shattered  and  pounded  the  soft  slate-rocks,  in  the  same  man- 
ner as  they  appear  to  have  contorted  the  sedimentary  beds  of 
the  east  coast  of  England  (as  shown  by  Mr.  Lyell)*,  and  of 
Tierra  del  Fuego  ?  Although  I  was  unable  to  find  any  beds 
on  Moel  Faban  likely  to  preserve  sea-shells,  yet,  considering 
the  absence  of  the  marks  of  the  passage  of  glaciers  over  it,  I 
cannot  doubt  that  the  boulders  on  its  surface  were  transported 
on  floating  ice. 

The  drifting  to  and  fro,  and  grounding  of  numerous  icebergs 
during  long  periods  near  successive  uprising  coast-lines,  the 
bottom  being  thus  often  stirred  up  and  fragments  of  rock 
dropped  on  it,  will  account  for  the  sloping  plain  of  unstratified 
till,  occasionally  associated  with  beds  of  sand  and  gravel,  which 
fringes  to  the  west  and  north  the  great  Caernarvonshire 
mountains. 

In  a  paper  read  before  the  Geological  Society  f,  I  have  re- 
marked that  blocks  of  rock  are  transported  by  floating  ice  un- 
der different  conditions;  1st,  by  the  freezing  of  the  sea,  in 
countries  where  the  climate  does  not  favour  the  low  descent 
of  glaciers  ;  2nd,  by  the  formation  of  icebergs  by  the  descent 
of  glaciers  into  the  sea,  from  mountains  not  very  lofty,  in  la- 
titudes (for  instance  in  that  of  Geneva,  or  of  the  mouth  of  the 
Loire,  in  the  southern  hemisphere)  where  the  surface  of  the 

*  "  On  the  Boulder  Formation  of  Eastern  Norfolk  ;"  Phil.  Mag.,  S.  3, 
vol.  xvi.  May  1840,  p.  351. 

t  May  5th.  1841,  "  On  the  distribution  of  the  Erratic  Boulders,  and  on 
the  contemporaneous  unstratified  deposits  of  South  America.''  [Phil.  Mag. 
S.  3,  vol.  xix.  p.  536.] 


186  Mr.  Darwin  on  the  Ancient  Glaciers  of  Caernarvonshire, 

sea  never  freezes ;  and  3rd,  by  these  two  agencies  united.  I 
have  further  remarked  that  the  condition  and  kind  of  the  stones 
transported,  would  generally  be  influenced  by  the  manner  of 
production  of  the  floating  ice.  In  accordance  with  these  views, 
I  may  remark  that  it  does  not  seem  probable  from  the  low 
level  of  the  Chalk-formation  in  Great  Britain,  that  rounded 
chalk-flints  could  often  have  fallen  on  the  surface  of  glaciers, 
even  in  the  coldest  times.  I  infer  therefore  that  such  pebbles 
were  probably  inclosed  by  the  freezing  of  the  water  on  the 
ancient  sea-coasts.  We  have,  however,  the  clearest  proofs  of 
the  existence  of  glaciers  in  this  country ;  and  it  appears,  that 
when  the  land  stood  at  a  lower  level,  some  of  the  glaciers, 
as  in  Nant-Francon,  reached  the  sea,  where  icebergs  charged 
with  fragments  would  occasionally  be  formed.  By  this  means 
we  may  suppose  that  the  great  angular  blocks  of  Welch  rocks, 
scattered  over  the  central  counties  of  England,  were  trans- 
ported*. I  looked  carefully  in  the  valleys  near  Capel-Curig 
and  in  Nant-Francon  for  beds  of  pebbles,  or  other  marks  of 
marine  erosion,  but  could  not  discover  any :  when,  however, 
Moel  Tryfan  and  Faban  stood  beneath  the  level  of  the  sea, 
inland  creeks  of  salt-water  must  have  stretched  far  up  or  quite 
through  these  valleys,  and  where  they  were  deep,  the  glaciers 
(as  at  present  in  Spitzbergenf)  would  have  extended,  floating 
on  the  surface  of  the  water,  ready  to  become  detached  in  large 
portions.  From  the  presence  of  boss-formed  rocks  low  down 
in  the  valley  of  Nant-Francon,  and  on  the  shores  of  the  Lakes 

*  On  the  summit  of  Ashley  Heath  in  Staffordshire,  there  is  an  angular 
block  of  syenitic  greenstone,  four  feet  and  a  half  by  four  feet  square,  and 
two  feet  in  thickness.  This  point  is  803  feet  above  the  level  of  the  sea. 
From  this  fact,  together  with  those  relating  to  Moel  Tryfan  and  Faban,  we 
must,  I  think,  conclude  that  the  whole  of  this  part  of  England  was,  at  the 
period  of  the  floating  ice,  deeply  submerged.  From  the  reasons  given  in 
my  paper  (Phil.  Trans.,  1839  [Phil.  Mag.  S.  3,  vol.  xiv.  p.  363.]),  I  do  not 
doubt  that  at  this  same  period  the  central  parts  of  Scotland  stood  at  least 
1300  feet  beneath  the  present  level,  and  that  its  emergence  has  since  been 
very  slow.  The  boulder  on  Ashley  Heath  probably  has  been  exposed  to  at- 
mospheric disintegration  for  a  longer  period  than  any  other  in  this  part  of 
England.  I  was  therefore  interested  in  comparing  the  state  of  its  lower 
surface,  which  was  buried  two  feet  deep  in  compact  ferruginous  sand  (con- 
taining only  quartz  pebbles  from  the  subjacent  new  red  sandstone),  with 
the  upper  part.  I  could  not,  however,  perceive  the  smallest  difference  in 
the  preservation  of  the  sharp  outlines  of  its  sides.  I  had  a  hole  dug  under 
another  large  boulder  of  dark  green  felspathic  slaty  rock,  lying  at  a  lower 
level;  it  was  separated  by  18  inches  of  sand,  (containing  two  pebbles  of 
granite,  and  some  angular  and  rounded  masses  of  new  red  sandstone)  from 
the  surface  of  the  new  red  sandstone.  One  of  the  rounded  balls  of  this 
latter  stone  had  been  split  into  two,  and  deeply  scored,  evidently  by  the 
stranding  of  the  boulder. 

t  Dr.  Martens  on  the  Glaciers  of  Spitzbergen,  New  Edinb.  Phil.  Journ. 
1841,  (vol.  xxx.)  p.  288. 


find  on  Boulders  transported  by  Floating  Ice.        187 

of  Llanberis  (310  feet  above  the  sea),  it  is  evident  that  gla- 
ciers filled  the  valleys  after  the  land  had  risen  to  nearly  its 
present  height ;  and  these  glaciers  must  have  swept  the  valleys 
clean  of  all  the  rubbish  left  by  the  sea.  As  far  as  my  very 
limited  observations  serve,  I  suspect  that  boss  or  dome-formed 
rocks  will  serve  as  one  of  the  best  criterions  between  the  ef- 
fects produced  by  the  passage  of  glaciers  and  of  icebergs*. 

Dr.  Buckland  has  described  in  detail  the  marks  of  the  pass- 
age of  glaciers  along  nearly  the  whole  course  of  the  great 
central  Welch  valleys  ;  I  observed  that  these  marks  were  evi- 
dent at  the  height  of  some  hundred  feet  on  the  mountain-sides, 
above  the  water-sheds,  where  the  streams  flowing  into  the  sea 
at  Conway,  Bangor,    Caernarvon,  and  Tremadoc,  divide : 
hence  it  appears  that  a  person  starting  from  any  one  of  these 
four  places  (or  from  some  way  up  the  valley  where  the  gla- 
cier ended),  might  formerly,  without  getting  off  the  ice,  have 
come  out  at  either  of  the  other  three  places,  or  low  down  in 
the  valleys  in  which  they  stand.     The  mountains  at  this  pe- 
riod must  have  formed  islands,  separated  from  each  other  by 
rivers  of  ice,  and  surrounded  by  the  sea.  The  thickness  of  the 
ice  in  several  of  the  valleys  has  been  great.     In  the  vale  of 
Llanberis  I  ascended  a  very  steep  mountain,  E.N.E.  of  the 
upper  end  of  the  upper  lake,  which  slightly  projects  where  the 
valley  bends  a  little.     For  the  lower  1000  feet  (estimated,  I 
think,  correctly)  the  marks  left  by  the  glacier  are  very  distinct, 
especially  near  the  upper  limit,   where  there  are  boulders 
perched  on  bosses  of  rock,  and  where  the  scores  on  the  nearly 
vertical  faces  of  rock  are,  I  think,  more  distinct  than  any 
others  which  I  saw.     These  scores  are  generally  slightly  in- 
clined, but  at  various  angles,  seaward,  as  the  surface  of  the 
glacier  must  formerly  have  been.     But  on  one  particular  face 
of  rock,  inclined  at  an  angle  of  somewhere  about  fifty  degrees, 
continuous,  well-marked  and  nearly  parallel  lines  sloped  up- 
wards (in  a  contrary  sense  to  the  surface  of  the  glacier)  at  an 
angle  of  18°  with  the  horizon.     This  face  of  rock  did  not  lie 
parallel  to  the  sides  of  the  main  valley,  but  formed  one  side 
of  the  sloping  end  of  the  mountain,  over  and  round  which  the 
ice  appears  to  have  swept  with  prodigious  force,  expanding 
laterally  after  being  closely  confined  by  the  shoulder  above 

*  In  the  Appendix  to  my  Journal  of  Researches  (1839),  I  endeavoured 
to  show  that  many  of  the  appearances  attributed  to  debacles,  and  to  the 
movements  of  glaciers  on  solid  land,  would  in  all  probability  be  produced 
by  the  action  of  stranded  icebergs.  I  have  stated  (p.  619),  on  the  author- 
ity of  Dr.  Richardson,  that  the  rocky  beds  of  the  rivers  in  North  America 
which  convey  ice,  are  smoothed  and  polished;  and  that  (p.  620)  the  ice- 
bergs on  the  Arctic  shore  drive  before  them  every  pebble,  and  leave  the  sub- 
marine ledges  of  rock  absolutely  bare. 


188       Mr.  Josiah  Rees's  Application  of  the  Formula 

mentioned.  At  this  point,  where  the  glacier  has  swept  to  the 
westward,  and  has  expanded,  its  surface  seems  in  a  short  space 
to  have  declined  much :  for  on  a  hill  lying  about  a  quarter  of 
a  mile  N.  W.  of  the  shoulder,  and  forming  a  lower  part  of  the 
same  range  (it  stands  S.S.E.  of  the  Victoria  Inn,  and  has  a 
reddish  summit),  the  marks  of  the  passage  of  the  glacier  are 
at  a  considerably  lower  level.  At  the  very  summit,  however, 
of  this  hill,  several  large  blocks  of  rock  have  been  moved  from 
their  places,  as  if  the  ice  had  occasionally  passed  over  the 
summit,  but  not  for  periods  long  enough  to  have  worn  it 
smooth. 

I  cannot  imagine  a  more  instructive  and  interesting  lesson 
for  any  one  who  wishes  (as  I  did)  to  learn  the  effects  produced 
by  the  passage  of  glaciers,  than  to  ascend  a  mountain  like  one 
of  those  south  of  the  upper  lake  of  Llanberis,  constituted  of 
the  same  kind  of  rock  and  similarly  stratified,  from  top  to 
bottom.  The  lower  portions  consist  entirely  of  convex  domes 
or  bosses  of  naked  rock,  generally  smoothed,  but  with  their 
steep  faces  often  deeply  scored  in  nearly  horizontal  lines,  and 
with  their  summits  occasionally  crowned  by  perched  boulders 
of  foreign  rock.  The  upper  portions,  on  the  other  hand,  are 
less  naked,  and  the  jagged  ends  of  the  slaty  rocks  project 
through  the  turf  in  irregular  hummocks ;  no  smooth  bosses, 
no  scored  surfaces,  no  boulders  are  to  be  seen,  and  this  change 
is  effected  by  an  ascent  of  only  a  few  yards  !  So  great  is  the 
contrast,  that  any  one  viewing  these  mountains  from  a  distance, 
would  in  many  cases  naturally  conclude  that  their  bases  and 
their  summits  were  composed  of  quite  different  formations. 


XXXI.  Application  to  particular  instances  of  the  general 
Formula  for  eliminating  the  Weights  of  Mixed  Bases.  By 
Josiah  Rees,  Jun.,  F.G.S.,  of  Her  Majesty's  Ordnance 
Geological  Survey  *. 

HPHE  general  formula  for  eliminating  the  weights  of  any  two 
•*■  bases,  where  the  whole  weight  of  any  particular  acid  with 
which  they  are  combined  has  been  previously  ascertained,  is 
not  easily  available  to  those  who  are  unaccustomed  to  mathe- 
matical inquiry. 

If,  however,  we  apply  the  general  rule  to  particular  in- 
stances, we  are  enabled  to  obtain  a  very  simple  place  for  each, 
by  the  application  of  which  the  weight  of  the  bases  may  be 
ascertained. 

I  have  thought  it  would  not  be  altogether  useless  to  draw 
up  a  few  such  rules  for  the  use  of  chemists. 
*  Communicated  by  the  Author. 


for  eliminating  the  Weights  of  Mixed  Bases.  189 

The  following  combinations  have  been  chosen  as  the  most 
likely  to  come  under  the  notice  of  the  practical  chemist: — 

Potash  and  soda  combined  with  sulphuric  acid ;  sodium  and 
magnesium  with  chlorine ;  sodium  and  calcium  with  chlorine ; 
lime  and  magnesia  with  carbonic  acid. 

The  equivalents  adopted  by  Brande  have  been  used  in  the 
calculation. 

Carbonic  acid  ...  22        Magnesium 12 

Chlorine 36         Potash 48 

Sulphuric  acid  ...  40         Soda 32 

Calcium 20         Potassium 40 

Lime 28         Sodium 24 

1 .  When  potash  and  soda  exist  in  combination  with  sul- 
phuric acid,  the  weight  of  mixed  sulphates  being  known,  and 
also  the  weight  of  acid  with  which  they  are  combined,  to  as- 
certain the  weight  of  each  base  present. 

Rule. — Multiply  the  whole  weight  of  material  experimented 
on  by  15;  from  the  product  subtract  27  times  the  weight  of 
the  acid  in  combination,  and  divide  the  remainder  by  5,  the 
quotient  will  be  the  weight  of  potash :  b  being  the  weight  of 
material  experimented  on,  and  a  the  known  weight  of  acid, 
the  rule  stands  thus : — 

15  b  —  27  a       .,  .  ,.    c     l    n 
==  the  weight  of  potash. 

The  whole  weight  of  acid  and  the  weight  of  potash  being  as- 
certained, the  weight  of  soda  is  of  course  at  once  known  by 
subtracting  the  weight  of  acid  and  potash  from  that  of  the 
whole  material  experimented  on. 

2.  When  magnesium  and  sodium  exist  in  combination  with 
chlorine,  the  whole  weight  of  the  chlorine  in  combination  be- 
ing known,  to  ascertain  the  weight  of  each  base. 

Rule. — Multiply  the  whole  weight  of  material  experimented 
on  by  6,  from  the  product  subtract  8  times  the  weight  of  the 
chlorine,  and  divide  the  remainder  by  3,  the  quotient  will  be 
the  weight  of  the  sodium : — 

=  weight  of  the  sodium. 

3  h 

3.  When  sodium  and  calcium  exist  in  combination  with 
chlorine,  the  weight  of  chlorine  being  known,  to  ascertain 
that  of  each  base. 

Rule. — Multiply  the  whole  weight  of  material  experimented 

on  by  18;  from  the  product  subtract  28  times  the  weight  of 

chlorine,  and  divide  the  remainder  by  3  ;  the  quotient  will  be 

the  weight  of  the  sodium : — 

18  6  —  28  a  .  i  ;    f      i- 
=  weight  of  sodium. 


190   Mr.  Davies  on  the  Employment  of  Polar  Coordinates 

4.  When  lime  and  magnesia  exist  in  combination  with  car- 
bonic acid,  the  whole  weight  of  the  acid  in  combination  being 
previously  known,  to  ascertain  the  weight  of  each  base. 

Rule. — Multiply  the  whole  weight  of  material  experimented 
on  by  77 ;  from  the  product  subtract  147  times  the  weight  of 
acid,  divide  the  remainder  by  22,  and  the  quotient  will  be  the 
weight  of  lime : — 

77  £  —  147  a  -v.    r.,1     r 

— =  weight  or  the  lime. 

22  & 

Crickhowel,  July  %  1842. 

XXXII.  On  theEmployment  of  Polar  Coordinates  in  expressing 
the  Equation  of  the  Straight  Line,  and  its  application  to  the 
proof  of  a  property  of  the  Parabola.  By  T.  S.  Davies, 
Esq.,  F.R.S.,  F.S.A.,  fyc,  Royal  Military  Academy,  Wool- 
wich *. 

A  BOUT  ten  years  ago  I  gave  in  a  note  to  my  paper  on 
**■  Spherical  Coordinates  (in  the  Trans.  Roy.  Soc.  Edinb., 
vol.  xii.)  the  general  equation  of  a  straight  line  in  reference 
to  polar  coordinates.  The  idea,  which  is  very  simple,  was 
suggested  by  the  method  which  I  had  employed  in  the  dis- 
cussion of  spherical  loci ;  the  equation  of  the  line  in  piano 
corresponding  to  that  of  the  great  circle  on  the  surface  of 
the  sphere:  and  it  was  made  apparent  that  the  treatment 
of  the  straight  line  by  such  means  was  quite  as  simple  and 
elementary  in  all  its  details  as  that  by  means  of  rectilinear  co- 
ordinates. 

Beyond  the  occasional    employment  of  the    expression 

d  r 
•    ,.'-to  express  the  angle  of  the  tangent  and  radius  vector,  or 

the  relation  between  the  perpendicular  on  the  tangent  and 
the  corresponding  radius  vector,  the  method  of  polar  coor- 
dinates has  been  generally  disregarded  by  mathematicians 
in  treating  of  the  tangents  and  normals  to  curve  lines :  and 
I  do  not  recollect  a  single  instance  where  the  general  polar 
form  of  the  equation  of  a  line  subject  to  its  adequate  number 
of  defining  conditions  has  even  been  noticed,  much  less  used, 
by  any  author,  prior  to  the  appearance  of  my  paper.  However, 
that  it  is  a  very  efficient  method  of  investigating  the  properties 
of  rectilineal  figures,  any  reader  may  readily  convince  him- 
self by  a  few  experiments  upon  such  theorems  as  express  those 
properties ;  and  I  wish  here  to  illustrate  its  utility  in  reference 
to  tangencies  by  the  investigation  of  a  theorem  which  has  ex- 

*  Communicated  by  the  Author. 


in  expressing  the  Equation  of  the  Straight  Line.      191 

cited  some  interest  amongst  the  readers  of  the  Philosophical 
Magazine,  and  which  treated  purely  by  rectangular  coordinates, 
involves  expressions  of  considerable  complexity. 

Theorem.  If  three  tangents  to  a  parabola  mutually  inter- 
sect, the  circle  described  about  the  triangle  formed  by  them  will 
always  pass  through  the  focus  of  the  parabola*. 

The  polar  equation  to  the  tangent  at  the  point  rl0l  of  any 
curve  is 

r  {cos  (0-00  -  sin  (0-0,)  ^J-|  =  rx. 

Edinb.  Trans.,  vol.  xii.  p.  408. 

And  the  equation  of  the  parabola,  referred  to  its  focus  as  pole 
and  diameter  as  origin  of  polar  angles,  is,  at  the  point  rx  Ql9 

^(1+008  0!)  =  2  a. 
From  (2.)  we  get 

drx  sin0t 

d    x     ~  1+COS0J ' 
which,  inserted  in  the  general  equation,  gives  at  once 

r  {cos  (0— 0j)  +  cos  (0-00  COS0J—  sin  (0— 0j)  sh^} 
=  rx  (1+cos0j), 

or  finally,  r  cos  (0—1 0  x)  cos  i  0!  =  a (1 .) 

Similarly,  r  cos  (0— A02)  cos  1  02  =  «,     (2.) 

and  r  cos  (0— i03)  cos|03  =  a,     (3.) 

which  represent  the  three  tangents  at  t\  01}  r^  02,  r3  03 ;  and 
from  which  the  proof  of  the  theorem  is  deducible  as  follows: 

Denote  by  Rj  6X  the  coordinates  of  the  intersection  the 
tangents  represented  (2,  3),  by  R282  that  of  (3,  1),  and  by 
R3  e3  that  of  (1,  2).     Then  we  get  immediately 


*i  =  i(02+03) 

Rj  =  a  sec  A 02  sec  A  03 

®i-»2=i  (*2-*i) 

e2  =  -§(03+0i) 

R2  =  a  sec  A  03  sec  ^  0t 

%-%=h  %-**> 

®3  =  2^1+02) 

R3  =  a  sec  \  01  sec  J  02 

e3—ei=2    (^1 — ^3) 

Hence, 

*  Wallace,  in  the  Mathem.  Repos.,  vol.  ii.  p.  54,  Old  Series,  and  in  his 
Conic  Sections,  p.  167 ;  Tirnmermanns.inQuetelet's  Correspondance  Math, 
et  Phys.,  torn.  ii.  p.  75;  Strong  and  Avery,  Gill's  Math.  Misc.  New  York, 
No.  6;  Jones  in  the  Gentleman's  Diary,  1831;  Poncelet,  Traite  des  pro- 
prietes  projectives,  section  iv.  Annates  des  Mathcmatiques,  tom.  viii.;  Phil. 
Mag.,  S.  3,  vol.  ix.  p.  100;  x.  pp.  32,  35;  xi.  p.  302;  and  Young's  Conic 
Sections,  p.  189. 

I  would  not  be  understood  to  contest  the  simplicity  of  the  geometrical 
methods  of  proving  this  theorem ;  but  merely  take  this  theorem  as  an  il- 
lustration of  the  occasional  advantage  of  the  polar  over  the  rectangular 
equation  of  the  tangent  to  a  curve. 


192  Mr.  Warrington  on  the  Change  of 

Rj  sin  (82  —  e3)  =  a  (tan  J  03—  tan  1  02) 
R2  sin  (63—  et)  =  a  (tan  A  5,-  tan  J  03) 
R3sin  {e1  —  62)  =  a  (tan  ^  02-  tan  £0,). 
By  addition  of  these,  we  have 
RT  sin  (62— e3)  +  R2  sin(e3-Oj)  +  R3  sin  (©i  — ©a)  =  °» 
which  is  the  criterion  of  the  circle  through  Rj  8j ,  R2  62, 
R3  63  passing  through  the  polar  origin,  or,  in  this  case,  the 
focus  of  the  parabola. 

It  may  not  be  irrelevant  to  remark,  that  the  geometrical 
property  expressed  by  the  values  of  e„  62,  63  in  terms  of 
0„  #2,  09  is  the  familiar  one  found  in  all  works  on  the  conic 
sections ;  as  in  Hutton's  Course,  for  instance,  at  vol.ii.  pp.  1 1 1, 
135,  147  of  the  11th  edition,  and  nearly  in  the  same  places 
in  the  edition  now  printing. 

Lines  drawn  to  the  focus  of  a  conic  section  from  the  intersec- 
tion of  two  tangents,  bisects  the  angle  formed  by  the  radii  vector  es 
drawn  to  the  points  of  contact. 

The  property  in  reference  to  the  other  conic  sections  is 
deducible  in  the  same  way,  as  will  be  obvious  on  forming  the 
equations  Of  the  tangent  in  each  of  them,  and  which  are 
put  down  here  for  the  ellipse  and  hyperbola : — 

r  {cos  (0-0J0  +  e  cos  }  =  a  (1-e2), 
and  r  {cos  (0— 0,)0— e  cos  }  =  a  (e2—  1). 

Many  other  properties  may  be  obtained  by  this  method 
with  great  simplicity  and  elegance;    but  the  method  being 
once  pointed  out,  the  details  are  too  elementary  to  require 
further  notice  in  this  place. 
Royal  Military  Academy, 
July  5,  1842. 

XXXIII.  On  the  Change  of  Colour  in  the  Biniodide  of  Mer- 
cury. By  Robert  Warington,  Esq.,  Secretary  to  the 
Chemical  Society  *. 

TT  is  well  known  that  when  a  solution  of  the  iodide  of  po- 
■*■  tassium  is  added  to  a  solution  of  the  bichloride  or  perni- 
trate  of  mercury,  a  yellow  precipitate,  passing  rapidly  to 
a  scarlet,  is  formed ;  this  is  the  biniodide  of  mercury.  It  is 
soluble  in  an  excess  of  either  of  the  agents  employed  for  its 
production,  and  if  this  act  of  solution  be  assisted  by  heat,  the 
biniodide  may  be  obtained,  as  the  solution  cools  in  fine  scarlet 
crystals,  having  the  form  of  the  octohedron  with  the  square 
base,  or  its  modifications. 

*  Communicated  by  the  Chemical  Society,  having  been  read  Feb.  1, 
1842.  Some  of  the  facts  related  in  this  paper  had  been  previously  ob- 
served by  Mr.  Talbot,  and  described  by  him  in  Phil.  Mag.  Third  Series, 
vol.  ix.  p.  2. — Edit. 


Colour  in  the  Biniodide  of  Mercury.  193 

If  this  precipitated  biniodide,  in  the  dry  state,  be  subjected 
to  the  action  of  heat,  it  becomes  of  a  bright  pale  yellow  colour, 
fuses  into  a  deep  amber-coloured  fluid,  and  gives  off  a  vapour 
which  condenses  in  the  form  of  rhombic  plates  of  the  same 
bright  yellow;-  these  crystals,  by  any  mechanical  disturbance, 
arising  from  the  unequal  contraction  of  their  molecules  in  cool- 
ing, from  varying  thickness  in  different  parts  of  the  same  cry- 
stal, or  from  partial  disintegration,  return  again  to  the  origi- 
nal scarlet  colour  of  the  precipitate,  the  change  commencing, 
in  the  latter  case,  from  the  point  ruptured,  and  spreading  over 
the  whole  of  the  crystalline  mass;  they  may  however  be  fre- 
quently preserved  in  the  yellow  state  for  a  great  length  of  time, 
if  sublimed  slowly  and  not  exposed  to  the  contact  of  other  sub- 
stances, which  is  readily  effected  by  conducting  the  sublima- 
tion in  closed  vessels,  and  allowing  the  crystals  to  remain  in 
them  undisturbed. 

The  resumption  of  the  scarlet  colour  has  been  attributed  to 
an  alteration  in  the  molecular  arrangement  of  the  crystals,  and 
it  was  with  the  view  of  clearly  ascertaining  this  point  that  the 
following  microscopic  investigations  were  undertaken. 

When  a  quantity  of  the  precipitated  biniodide  is  sublimed, 
the  resulting  crystals  are  very  complicated  in  their  structure, 
consisting  of  a  number  of  rhombic  plates,  of  varying  size,  su- 
perposed, sometimes  overlapping  each  other  and  causing  con- 
siderable variableness  in  their  thickness,  but  generally  leaving 
the  extreme  angle  and  the  two  lateral  edges  clear  and  well- 
defined  ;  the  annexed  sketch,  taken  by  the  camera  lucida  from 
the  field  of  view  of  the  microscope,  will  give  a  better  idea  of 
their  character.  The  length  of  these  crystals  was  about  *01 5 
of  an  inch  in  length.  On  cooling,  the  first  change  that  is  ob- 
served is  usually  a  scarlet  marking,  commencing  at  the  ex- 
treme angle  and  extending  gradually  inwards,  always  retain- 
ing a  perfectly  well-defined  line  in  its  progress;  when  this 
change  has  reached  as  far  as  the  line  ab,  fig.  1,  the  scarlet 
line  will  suddenly  shoot  along  one  of  the  lateral  edges,  as  shown 
at  c  d,  and  instantly  the  whole  mass  is  converted,  in  a  most  rapid 
and  confused  manner,  which  the  eye  in  vain  endeavours  to  fol- 
low, to  the  scarlet  colour,  the  crystal  being  frequently,  if  de- 
tached, twisted  and  contorted  during  the  transition. 

In  order  to  obtain  these  crystals  in  a  more  defined  and 
clearly  developed  form,  a  small  glass  cell  was  constructed  of  two 
slips  of  window-glass,  leaving  a  space  of  about  the  thickness  of 
cartridge  paper  between  the  upper  and  under  plates,  in  which 
the  sublimations  could  be  readily  conducted,  and  the  whole  of 
the  subsequent  changes  at  once  submitted  to  the  microscope  ; 
Phil.  Mag.  S.  3.  Vol.  21.  No.  137.  Sept.  18*2.       O 


194<  Mr.  Warington  on  the  Change  of 

by  this  means  beautifully  well-defined  and  perfect  crystals 


Fig.  1. 


were  obtained,  having  the  form  of  right  rhombic  prisms,  as  in 


Fig.  2. 


the  accompanying  outlines, 
fig.  2,  a  and  b.  The  follow- 
ing interesting  phagnomena 
were  then  observed  :  a  de- 
fined scarlet  line  of  varying 
breadth  would  shoot  across 
the  crystal,  as  at  1 .  c,  d,  e,f, 
fig.  2,  and  then  gradually 
spreadthroughoutthewhole 
of  its  structure,  keeping  a 
straight  and  well-defined 
line  in  its  onward  progress, 


until  the  whole  had  undergone  the  change  of  colour.  Nos.  2,  3, 
4f,  5  in  e,  and  No.  2  in  f,  are  the  stages  which  the  transition  had 
reached  at  intervals  of  observation;  in  many  cases,  after  the 
crystal  has  undergone  this  metamorphosis,  two  angles  can  be 
distinctly  seen,  as  at  e,  fig.  1,  and  at  times  two  edges  are  visible, 
as  at  c  6  and  d  6,  fig.  2.  This  observation  must  of  course  de- 
pend entirely  on  the  position  of  the  crystal  to  the  eye  of  the 
observer. 

These  phaenomena  prove,  I  consider,  in  the  most  perfect 
manner,  that  the  change  in  the  colour  of  this  compound  arises 


•©" 


V 

D 


Colour  in  the  Biniodide  of  Mercury.  195 

from  the  plates  of  the  crystal  having  been  separated  from  each 
other,  by  the  means  alluded  to,  in  the  direction  of  their  clea- 
vages ;  and  in  further  confirmation  of  this  view,  the  lamina? 
so  separated  may,  by  the  sudden  application  of  heat,  be  again 
fused  together,  and  the  yellow  colour  reproduced  without  ma- 
terially altering  the  dimensions  of  the  crystal,  a  slight  round- 
ing of  the  edges  from  partial  sublimation  being  the  only  other 
concomitant. 

When  the  temperature  is  raised  slowly  and  the  sublimation 
conducted  with  great  care,  a  verylarge  proportion  of  red  cry- 
stals, having  a  totally  different  form,  are  obtained,  the  octahe- 
dron with  the  square  base,  YW.  3. 
as  shown  fig.  3,  a,  b,  c,  d,  e. 
If,  however,  the  heat  is 
quickly  raised,  the  whole 
mass  of  the  sublimed  cry- 
stals are  yellow  and  of  the 
rhombic  form.  It  is  evident 
from  these  facts,  that  the 
biniodide  of  mercury  has 
two  vapours  which  are  given  off  at  different  temperatures, 
and  also  that  it  is  dimorphous,  which  facts  have  been  sub- 
stantiated by  some  experiments  of  M.  Frankenheim,  who  has 
carefully  examined  this  part  of  the  subject. 

From  the  circumstance  that  the  first  effect  which  occurs  in 
the  process  for  preparing  this  iodide  by  precipitation  is  the  pro- 
duction of  a  yellow  powder  which  passes  rapidly  through  the 
orange  colour  to  a  scarlet,  I  was  induced  to  submit  this  phe- 
nomenon also  to  the  test  of  microscopic  examination,  and  with 
this  valuable  instrument  of  research,  results  were  exhibited 
which  could  not  have  been  anticipated.  As  I  expected,  the 
precipitate  was  in  small  crystalline  grains,  and  the  first  step  of 
the  investigation  was  to  effect  its  formation  in  the  field  of  view 
of  the  microscope,  so  as  to  observe,  directly  as  they  occurred, 
the  transitions  of  colour  which  have  been  alluded  to,  and  this 
was  effected  by  the  following  means : — A  slip  of  common  win- 
dow-glass, about  three  inches  long  by  one  and  a  half  wide,  and 
having  a  very  narrow  slip  attached  on  one  of  its  edges,  so  as 
to  act  as  a  ledge,  was  taken,  and  a  drop  of  the  salt  of  mercury 
employed  placed  on  it ;  this  was  then  covered  with  a  small 
piece  of  extremely  thin  glass,  about  one  inch  long  by  half  an 
inch  wide,  and  the  whole  carefully  adjusted  to  focus  in  the 
field  of  the  instrument;  the  iodide  of  potassium  was  then  in- 
troduced by  capillary  attraction  between  the  glasses.  The 
instant  the  solutions  came  in  contact,  a  myriad  of  pale-yellow 
crystals,  having  the  same  rhombic  form  as  those  obtained  by 

02 


196  Mr.Warington  on  Change  of  Colour  in  Biniodide  of 'Mercury. 

sublimation,  formed  in  a  curved  line  across  the  field  of  view 
and  extended  slowly  downwards ;  by  the  strong  transmitted 
light  these  minute  crystals  appeared  colourless ;  but  when 
viewed  by  reflected  light,  the  pale  yellow  colour  was  readily 
apparent.  After  a  short  interval  a  very  extraordinary  change 
commenced;  the  crystals,  which  had  been  perfectly  sharp  and 
well-defined,  became  ragged  at  their  edges,  as  though  some 
dissolving  action  were  going  on,  gradually  decreased  in  size, 
and  at  last  disappeared  altogether;  but  as  this  act  of  solution 
progressed,  numbers  of  red  crystals  made  their  appearance, 
forming  across  the  field  and  following  at  a  regular  distance 
the  yellow  crystals  as  they  disappeared,  and  occupying  their 
place.  These  red  crystals,  which  appear  to  be  formed  by  the 
disintegration  through  the  medium  of  solution,  if  I  may  be 
allowed  the  expression,  from  those  first  produced,  had  the 
form  of  the  octohedron  with  the  square  base,  exactly  similar 
to  those  procured  by  careful  sublimation  at  a  low  heat,  only 
modified  in  the  most  beautiful  manner.  Some  few  of  these 
are  sketched  in  the  forms,  «,&,c, 
d,  e,f,  g,  //,  fig.  4.  When  either 
the  salt  of  mercury  or  the  iodide 
of  potassium,  employed  in  the 
production  of  the  biniodide  of  ( 
mercury,  was  in  excess,  another 
curious  act  of  disintegration  took 
place ;  the  red  crystals  in  fig.  4- 
were  slowly  dissolved,  aproperty 
mentioned  in  the  first  part  of  this  ft, 
paper,  the  first  act  of  solution  y  i     \ 

commencing  apparently  by  the    k  f^l      k   _J 

disjunction  of  the  crystals  «,  b, 

c,  f  g,  h,  at  the  lines  of  marking,  these  lines  being  at  first 
bright  red,  and  gradually  deepening  in  colour  when  the 
act  of  solution  commenced,  and  at  last  perfect  separation 
taking  place,  so  that  the  light  could  be  seen  between  the 
compartments.  At  times  the  field  would  become  dry  from 
evaporation,  and  some  of  the  yellow  rhombic  crystals  which 
had  not  been  dissolved,  prior  to  the  formation  of  the  octohe- 
dra  with  the  square  base,  were  observed  with  scarlet  lines  on 
them  similar  to  the  first  act  of  transition  in  the  sublimed  cry- 
stals, as  shown  at  g  1  and  2  in  fig.  2. 

By  polarized  light  the  appearances  now  described  were 
beautiful  beyond  all  description,  the  yellow  crystals  present- 
ing the  most  superb  and  brilliant  colours,  varying  in  hue  with 
the  varied  thickness  of  the  crystalline  plate,  and  in  the  dark 
field  having  the  appearance  of  the  most  splendid  gems  the 


Mr.  Croft  on  a  new  Oxalate  of  Chromium  and  Potash.  197 

imagination  can  conceive :  the  red  crystals  do  not  appear  to 
be  affected  by  polarized  light,  so  far  as  the  display  of  colour 
is  concerned. 

The  magnifying  powers  used  in  these  investigations  were, 
for  the  experiments  on  the  sublimed  crystals,  200  times  linear 
measurement  or  diameters;  in  the  precipitated  compound, 
620  diameters. 

XXXIV.  On  a  new  Oxalate  of  Chromium  and  Potash.     By 
Henry  Croft,  Esq.* 

IT  is  well  known  that  in  1830  Wilton  Turner  accidentally 
discovered  a  salt  composed  of  oxalate  of  the  oxide  of  chro- 
mium and  oxalate  of  potash.  Its  curious  optical  properties 
have  been  examined  by  Brewsterf.  Gregory  also  discovered 
the  same  salt  independently,  and  proposed  a  much  better  me- 
thod for  obtaining  it  than  that  used  by  Turner,  which  con- 
sisted in  adding  oxalic  acid  to  a  solution  of  bichromate  of  po- 
tash until  effervescence  ceased  :  the  solution  became  deep 
green  or  black,  and  on  evaporation  yielded  beautiful  crystals 
of  the  black  salt.  Gregory  supposed  it  to  consist  of  3  equi- 
valents of  oxalic  acid,  2  of  potash,  1  of  oxide  of  chromium, 
and  6  of  water.  Its  true  composition,  3  (KO,  C2  Oa)  4-  Cr2  Oa, 
3  C2  03  +  6  HO  has  been  shown  by  Graham  and  Mitscher- 
lich,  who  have  also  prepared  a  number  of  salts  similarly  con- 
stituted. 

On  attempting  to  prepare  the  black  salt  by  Turner's  method 
I  could  never  completely  succeed,  but  obtained  in  its  stead, 
when  a  very  concentrated  hot  solution  of  the  bichromate  was 
employed,  a  red  granular  precipitate,  which  proved  to  be  a 
new  salt,  and  forms  the  subject  of  the  present  notice. 

Perhaps  the  best  method  of  preparing  it  is  that  above  de- 
scribed, viz.  to  employ  as  concentrated  a  solution  of  the  bichro- 
mate as  possible,  in  which  case  the  salt  crystallizes  out  on 
cooling.  The  precipitated  salt  must  be  redissolved  in  a  small 
quantity  of  water  and  allowed  to  crystallize.  It  is  however 
one  of  the  most  difficult  salts  to  crystallize  that  is  known :  in 
nine  cases  out  of  ten  it  separates  in  the  form  of  a  somewhat 
granular  bluish  gray  powder,  and  it  appears  to  be  only  under 
particular  circumstances  that  it  will  crystallize  well,  which, 
however,  I  was  not  able  to  discover.     It  does  not  seem  to 

*  Communicated  by  the  Chemical  Society,  having  been  read  February  15, 
1842. 

[t  See  Phil.  Mag.  Third  Series,  vol.  vii.  p.  436.  Some  of  the  optical  and 
crystallographical  properties  of  this  salt  have  also  been  described  by  Mr. 
Talbot,  in  Phil.  Mag.  Third  Series,  vol.  x.  p.  218,  and  vol.  xiv.  p.  21.— 
Edit.] 


198  Mr.  Croft  on  a  new  Oxalate  of  Chromium  and  Potash, 

crystallize  any  better  by  spontaneous  evaporation  than  out  of 
a  very  concentrated  solution;  it  seems  however  to  form  more 
regularly  in  warm  air,  as  in  summer.  The  best  crystals  are 
generally  formed  on  the  surface  of  the  solutions  :  they  are  very 
minute,  in  the  form  of  triangular  plates ;  when  the  crystals 
form  a  mass  at  the  bottom  of  the  liquid  the  plates  are  thicker, 
but  their  form  is  indistinguishable.  The  salt  is  of  a  deep  red 
colour  by  reflected  as  well  as  by  transmitted  light;  the  solu- 
tion is  green,  or  even  black  (when  concentrated)  by  reflected 
and  red  by  transmitted  light.  The  solution  when  at  a 
boiling  temperature  remains  red,  as  is  seen  best  by  candle- 
light :  the  same  is  the  case  with  the  solution  of  the  black  salt, 
which  shows  that  the  purple  oxide  of  chromium  contained  in 
these  salts  is  not  converted  by  a  boiling  heat  into  its  green 
modification;  the  purple  oxide  must,  however,  as  is  well  known, 
be  first  brought  into  combination  with  the  oxalic  acid,  for  the 
black  salt  can  never  be  obtained  by  dissolving  green  oxide  of 
chromium  in  binoxalate  of  potash. 

A  solution  of  caustic  potash  added  to  a  solution  of  the  red 
salt  turns  it  bright  green,  but  causes  no  precipitate  until  boiled, 
when  the  greater  part  of  the  oxide  of  chromium  is  thrown 
down.  Carbonates  of  the  alkalies  partly  change  the  colour 
in  the  same  manner,  but  do  not  precipitate  the  oxide  so  readily. 
Ammonia  causes  no  precipitate,  nor  does  chloride  of  calcium, 
owing  to  the  formation  of  Dingler's  oxalate  of  chromium  and 
lime;  when  ammonia  is  added  a  green  precipitate  containing 
oxide  of  chromium  is  formed. 

This  salt  contains  a  large  quantity  of  water  of  crystalliza- 
tion, which  can  only  be  driven  out  by  a  strong  heat,  as  is  also 
the  case  with  the  black  salt  (Graham).  It  loses  about  15-16 
per  cent,  at  100°  cent.,  and  19  per  cent,  at  200°  cent.  The 
last  portions  of  water  can  only  be  driven  out  at  300°  cent. 
Near  this  point  the  salt  begins  to  be  decomposed,  and  conse- 
quently the  determination  of  the  water  is  rendered  somewhat 
difficult.  per  cent. 

0-9986  gramme  of  salt  lost  0*2638  water  =  26*42 

0-7481  0*1965     ...      =  26'27 

0-8971  0-2532     ...      =  28'22 

The  determinations  of  the  oxide  of  chromium  and  the  po- 
tash were  performed  in  the  following  manner.  The  salt  was 
heated  red-hot :  in  this  operation  great  care  must  be  taken, 
for  the  salt  possesses  the  curious  property  of  decomposing 
with  considerable  violence  (without  explosion)  into  a  green 
powder,  which  unless  the  heat  is  applied  very  gradually,  is 
forced  out  of  the  crucible,  and  the  analysis  is  thus  lost.  When 
the  temperature  is  raised  gradually  the  crystals  retain  their 


Mr.  Croft  on  a  new  Oxalate  of  Chromium  and  Potash.  199 

form, but  become  of  a  bright  dark  green  colour :  as  soon  as 
the  decomposition  of  the  oxalates  commences  they  fall  into  a 
light  green  powder,  which  when  stronger  heated  becomes 
brown.  In  closed  vessels  carbonate  of  potash  is  formed;  in 
open  ones,  when  the  heat  is  continued  for  a  length  of  time, 
cnromate  is  produced.  This  chromate  must  be  extracted  by 
water,  reduced,  and  the  oxide  of  chromium  precipitated  by 
ammonia :  in  this  operation,  however,  it  is  better  to  evaporate 
the  ammoniacai  solution  to  dryness,  as  the  ammonia  always 
dissolves  a  small  quantity  of  the  oxide.  This  method  is  pre- 
ferable to  that  usually  employed  (Heinrich  Rose's  Analytical 
Chemistry) :  the  ammoniacai  and  potash  salts  must  be  dis- 
solved out,  evaporated,  the  ammonia  driven  off,  and  the  potash 
determined  either  as  chloride  or  by  means  of  platinum. 

The  oxalic  acid  may  be  determined  by  boiling  the  salt  with 
sulphuric  acid,  as  proposed  by  Prof.  Graham. 

The  salt  being  excessively  difficult  to  crystallize,  it  seldom 
happens  that  a  perfectly  homogeneous  substance  can  be  ob- 
tained for  analysis :  the  method  of  analysis  is  moreover  some- 
what complicated,  and  consequently  the  analyses  do  not  agree 
so  perfectly  as  could  be  desired. 

i.  a.  in.  iv.  v.  vi. 

Cr2Os  21*80     21-83     23*11     22'05     21-10     24*11 
KO       13-18     13-11     12-22     12-92 
C2Oa    37*00     36-98  40-89 

The  water  as  obtained  by  other  experiments,  is 
H  O         26*42         26-27         28*22 

The  most  plausible  formula  is  KO,  C2  03  +  Cr2  09  3  C2  Oa 
-1-  12  HO. 


C203     4 

1811*50 

38*098 

Cr2Os  1 

1003-63 

21*107 

KO      1 

589*92 

12*405 

HO    12 

1349*75 

28*390 

4754-80        100*000 

This  differs  from  the  black  salt  in  containing  one  atom  of 
basic  oxalate  instead  of  three.  It  may  be  said  to  be  related 
to  the  black  salt  in  the  same  way  as  metaphosphates  are  to 
phosphates.  It  is  evident,  therefore,  that  if  we  add  two  atoms 
of  oxalate  of  potash  to  one  atom  of  the  red  salt,  we  ought 
to  obtain  the  black  salt,  which  is  indeed  the  case. 

2*37  grammes  of  red  salt  were  mixed  with  1*15  gr.  of  oxalate 
of  potash  (these  are  the  atomic  proportions),  the  solution 
boiled  and  evaporated,  they  yielded  3*119  grs.  of  the  black 
salt  in  good  crystals,  and  perfectly  pure  :  according  to  theory 
it  ought  to  have  given  3*070.  The  weight  of  the  black  salt 
must  be  equal  to  that  of  the  red  salt,  plus  two  atoms  of  anhy- 


200  Mr.  Croft  on  a  neta  Oxalate  of  Chromium  and  Potash. 

drous  oxalate  of  potash,  minus  six  atoms  of  water.  The 
agreement  of  the  experiment  with  the  calculation  speaks  for 
the  correctness  of  the  above  formula,  in  which  one  might, 
perhaps,  otherwise  not  place  so  much  confidence. 

The  constitution  of  this  salt  led  me  to  consider  the  theory 
of  its  formation,  and  also  that  of  the  black  salt,  more  particu- 
larly as  in  employing  the  known  formula}  for  making  the  black 
salt  I  always  obtained  it  mixed  with  other  bodies. 

In  forming  the  red  salt  from  bichromate  of  potassa,  7  atoms 
of  oxalic  acid  are  required.  K  O,  2  Cr  03  and  7  C2  Os  = 
K  O,  C2  03  +  Cr2  03,  3  C2  Osand  3  C2  03  +  3  O,  or  6  C  02. 
On  mixing  the  two  substances  in  this  proportion  I  obtained 
perfectly  pure  red  salt.  It  is  evident  that  seven  atoms  of  ox- 
alic acid,  either  free  or  in  combination  with  potash,  must  be 
used  in  making  the  black  salt.  None  of  the  numbers  in  the 
formulae  given  for  preparing  the  black  salt  agree  with  this. 

Dr.  Gregory  gives  190  parts  bichromate  of  potash,  157'5 
parts  crystallized  oxalic  acid,  and  517  parts  binoxalate  of  pot- 
ash ;  that  is,  one  atom  of  the  bichromate,  two  atoms  oxalic 
acid,  and  three  of  binoxalate  of  potash;  on  trying  these  num- 
bers I  obtained  a  mixture  of  black  salt  with  oxalate  and  chro- 
mate  of  potash. 

Prof.  Graham  proposes  one  part  of  bichromate,  two  of  bi- 
noxalate, and  two  of  crystallized  oxalic  acid.  In  these  pro- 
portions a  large  quantity  of  chromate  of  potassa  remains  un- 
decomposed,  which  requires,  if  19  grains  bichromate,  23  grains 
binoxalate,  and  16  grains  crystallized  oxalic  acid  be  taken, 
exactly  36  grains  of  crystallized  oxalic  acid  to  effect  its  perfect 
decomposition,  and  making  the  whole  quantity  of  oxalic  acid 
52  grains. 

According  to  the  formula  which  I  would  propose,  there  are 
required  19  grains  bichromate  of  potash 

23     ...      oxalate  of  potash 
55     ...      crystallized  oxalic  acid. 

If  the  salts  be  taken  in  these  proportions,  nothing  but  black 
salt  is  obtained ;  it  is  however  better  to  evaporate  the  whole 
to  dryness  and  then  re-dissolve. 

I  have  not  been  able  to  obtain  an  intermediate  salt,  namely, 
2  K  O,  C2  03  4-  Cr2  03,  3  C2  03.  This,  if  it  exists,  ought  to 
be  produced  from  two  atoms  chromate  of  potash,  and  eight 
atoms  oxalic  acid  :  I  obtained,  however,  oxalate  of  potash  and 
red  salt. 

A  similar  salt  may  probably  exist  with  oxide  of  iron,  but 
it  does  not  crystallize.  On  dissolving  sesquioxide  of  iron  in 
quadroxalate  of  potash  a  solution  is  obtained,  which  dries  to 
a  brown  gummy  mass  without  traces  of  crystallization. 


[  201  ] 


XXXV.  Some  additional  Observations  on  the  Red  Oxalate 
of  Chromium  and  Potash.  By  Robert  Warington,  Esq., 
Secretary  to  the  Chemical  Society*. 

tTAVING  in  the  year  1832  obtained  this  salt  by  the  same 
-■■•*■  method  as  that  described  by  Mr.  Croft,  namely,  in  the 
endeavour  to  prepare  the  dark  blue  oxalate  of  chromium  and 
potash  by  the  process  originally  given  by  its  discoverer  Dr. 
Wilton  Turner,  and  having  in  my  possession  some  crystals  of 
a  much  larger  size  than  those  usually  obtained,  I  was  induced 
to  avail  myself  of  the  kind  offer  of  Professor  Miller  of  Cam- 
bridge, "  to  determine  the  form  of  any  crystalline  products 
that  the  members  of  the  Society  might  obtain  in  their  re- 
searches," and  have  great  pleasure  in  laying  before  the  So- 
ciety the  following  letter  and  measurements : — 

"  St.  John's  College,  Cambridge,  April  25,1842. 

"  Dear  Sir. — The  crystals  of  the  oxalate  of  chromium  and  potash 
are  represented  in  the  accompanying  figure.  The  numbers  expressing 
the  angles  between  normals  to  the  faces  must  be  considered  as  rough 
approximations  only,  for  although  I  measured  all  the  measurable 
crystals  you  sent  me,  the  variations  of  the  angles  between  corre- 
sponding faces  showed  that  the  crystals  were  by  no  means  so  perfect 
as  could  be  wished. 

"  The  angles  given  are  however  abundantly  accurate  for  the  pur- 
pose of  identifying  the  substance.  One  of  the  crystals  was  a  twin, 
the  face  (a)  being  the  twin  face  or  the  face  with  respect  to  which 
the  two  individuals  were  symmetrically  situated. 

"  Oxalate  of  Chromium  and  Potash.     System  Oblique  prismatic. 

'*■  Angles  between  normals  to  the  faces  of 
the  crystal. 


ac  70° 

45' 

cp  50° 

40' 

ah  33 

2 

cm  77 

32 

ch  37 

43 

a  r  61 

0 

bp  53 

13 

«/78 

30 

ck  59 

16 

a'q  63 

50 

ap  47 

49 

bfZl 

40 

am  49 

5 

"  The  faces  ap  rf  q  are  all  in  one  zone ;  h  p  b  are  in  one  zone  ; 
k  q  b  are  in  one  zone ;  a  he  k  are  in  one  zone.  The  other  zones  are 
sufficiently  well  indicated  by  the  parallelisms  of  the  edges. 

"  The  symbols  of  the  faces  are, — a  (100),  b  (010),  c  (001),  h  (101) 
p  (111),  q  (111),/(011),  m  (110),  k  (101),  r  (112). 

"  I  remain  yours  faithfully, 

"  W.  H.  Miller." 

*  Communicated  by  the  Chemical  Society,  havinsr  been  read  Mav  17 
1842.  J      ' 


202    Prof.  Kelland's  Reply  to  some  Objections  against  the 

These  crystals,  submitted  to  measurement  by  Professor 
Miller,  were  obtained  by  slow  spontaneous  evaporation:  the 
difficulty  of  procuring  this  salt  in  crystals  of  any  size  has  been 
fully  pointed  out  by  Mr.  Croft. 

I  have  only  one  observation  which  does  not  coincide  with  Mr. 
Croft's  statements,  but  which,  however,  confirms  in  a  great 
measure  the  results  of  his  analysis;  I  allude  to  the  statement 
that  these  double  salts  of  chromium  cannot  be  formed  by  the 
direct  combination  of  their  ingredients.  The  process  which  I 
have  followed  has  been  to  digest  the  hydrated  oxide  of  chro- 
mium in  a  mixed  solution  of  oxalic  acid  and  oxalate  of  potash 
in  the  proportions  indicated  by  analysis,  and  when  it  ceases  to 
dissolve  the  oxide,  to  decant  the  clear  solution  and  allow  it  to 
crystallize.  By  the  same  means  the  analogous  salts  of  soda 
and  ammonia  have  been  obtained,  but  not  in  crystals  suffi- 
ciently large  for  measurement,  as  also  other  double  salts  of 
chromium.  To  prepare  the  hydrated  oxide  of  chromium, 
the  best  and  most  ceconomical  process  that  I  have  found,  is 
to  take  150  grs.  of  the  bichromate  of  potash  and  200  grs.  of 
liquid  sulphuric  acid,  oil  of  vitriol,  these  proportions  being 
nearly  in  the  ratio  of  their  atomic  weights,  so  that  the  chrome 
alum,  sulphate  of  the  green  oxide  of  chromium  and  potash, 
may  be  formed ;  the  deoxidation  of  the  chromic  acid  is  easily 
effected  by  the  addition  of  a  little  sugar  and  boiling  the  solu- 
tion. When  the  deoxidation  is  complete,  the  green  oxide 
may  be  precipitated  by  ammonia  or  by  a  carbonated  alkali, 
and  only  requires  to  be  well  washed  to  remove  all  trace  of 
alkali  or  saline  matter. 

XXXVI.    Reply  to  some  Objections  against  the  Theory  of  Mo- 
lecular Action  according  to  Newton's  Lww.     By  the  Rev.  P. 
Kelland,  M.A.,  F.R.SS.  L.  $  E.,  F.C.P.S.,  &>c,  Professor 
of  Mathematics  in  the  University  of  Edinburgh,  late  Fellow 
and  Tutor  of  Queen's  College,  Cambridge. 
[Continued  from  p.  130.] 
2.  HPHE  next  objection  to  the  molecular  hypothesis  of  par- 
-*•   tides  acting  on  each  other,  with  forces  varying  inversely 
as  the  square  of  the  distance,  is  that  the  equilibrium  of  such  a 
system  would  not  be  stable.     This  objection  is  stated  by  Mr. 
Earnshawin  his  memoir,  Art.  15.  The  argument  is  as  follows. 
The  force  due  to  a  displacement  parallel  to  either  principal 
axis  depends  on  the  second  differential  coefficient  of  V,  with 
respect  to  the  coordinate  along  that  axis.     Now  the  sum  of 
the  second  differential  coefficients  for  the  three  coordinates  is 
zero.     Hence  one  of  them  must  be  positive,  and  the  corre- 
sponding force  put  in  play  acts  to  draw  the  particle^owz  its 
system  of  rest.     Of  course  this  reasoning  depends  on  the  as- 


Theory  of  Molecular  Action  according  to  Newton's  Law,  203 

sumption  that  — 5,  &c.  are  not  zero.     In  the  contrary  case, 
ax1 

as  Mr.  Earnshaw  had  previously  pointed  out  (Art.  8),  "  the 

displacements  of  particles  would  not  bring  into  action  any 

forces  of  restitution."     Another  part  of  the  objection  relates 

to  the  boundaries  of  the  medium,  or  rather  of  space.     "  If  the 

particles  of  aether  exert  a  repulsive  action  on  each  other,  they 

will  naturally  endeavour  to  disperse  themselves  throughout 

all  space,  and  form  a  medium  coextensive  with  the  boundaries 

of  the  universe.     Here,  then,  a  formidable  difficulty  presents 

itself  to  our  notice.     If  the  medium  be  of  finite  dimensions 

it  must  be  inclosed  in  an  envelope  capable  of  restraining  the 

expansive  energy  of  the  whole  mass  of  particles.     The  more 

extensive  the  medium,  the  greater  must  be  the  strength  of  the 

envelope.     Is  it  probable  that  the  constitution  of  the  universe 

is  such  as  to  require  that  the  whole  should  be  enclosed  in  a 

huge  vessel  of  inconceivable  strength?"  (Art.  20.)    The  author 

then  goes  on  to  remove  the  difficulty  by  assuming  a  law  of 

force,  partly  attractive,  partly  repulsive. 

In  replying  to  these  objections  we  will  reverse  their  order. 

a.  The  difficulty  thrown  out  relative  to  the  equilibrium  of 
the  remote  parts  of  space  is  one  which  has  often  presented 
itself,  but  from  a  consideration  of  which  philosophers  have,  in 
general,  cautiously  abstained.  The  Newtonian  system  of  the 
universe  is  beset  with  difficulties  of  a  similar  nature,  which, 
although  by  no  means  satisfactorily  removed,  are  never  re- 
garded as  subversive  of  the  hypothesis.  We  must,  I  conceive, 
be  content  with  a  theory  capable  of  explaining  phaenomena 
which  come  within  the  limits  of  our  own  observation,  without 
requiring  that  it  should  penetrate  to  the  boundaries  of  the 
universe,  if,  in  truth,  such  boundaries  exist.  I  shall  consider 
myself,  therefore,  at  liberty  to  pass  over  this  objection,  with 
merely  requesting  that,  should  it  be  pressed,  I  may  be  informed 
how  it  is  got  over  in  the  Newtonian  system.  I  shall  merely 
add  that  the  molecular  hypothesis  does  not  assume  that  all 
the  particles  act  with  attractive,  or  all  with  repulsive  forces. 

b.  We  proceed  to  examine  the  circumstances  under  which 
the  equilibrium  may  be  neuter.  It  appears  to  me  that  this  is 
really  the  state  of  things  in  nature,  and  accordingly,  when  re- 
plying to  Mr.  Earnshaw  before  the  Philosophical  Society  of 
Cambridge,  a  little  more  than  two  years  ago,  I  argued  in 
support.  I  then  expressed  my  belief  that,  in  a  medium  of 
symmetry,  no  force  whatever  is  put  in  play  on  a  particle  by  its 
displacement  alone.  Subsequent  investigation  has  confirmed 
me  in  my  conjecture.  So  far  as  I  had  proceeded  in  the  in- 
vestigation I  found  that  V  appeared  to  be  constant,  so  that  all 


204     Prof.  Kelland's  Reply  to  some  Objections  against  the 

dV    d?V    d3V 
the  differential  coefficients  -7-?,  -nm  t^j  &c«  are  zero;  and 

df    djl    d/a 

since  the  force  put  in  play  on  a  particle  by  a  displacement  I 

dV 
depends  on  the  expansions  of  -r-p  &c,  and  therefore  of  V 

in  terms  of  5,  it  is  evident  that  the  force  is  zero.     The  equili- 
brium is  consequently  what  is  technically  called  neuter. 

The  following  investigation  is  copied  from  the  paper  above 
referred  to.     The  complete  demonstration  of  the  proposition 

d"V 
that    ,  fn    is  equal  to  zero,  involves  some  little  analysis  ;  and 

as  it  leads  to  a  number  of  most  important  results,  as,  for  in- 
stance, that  2  m  (x  — /)  nf{r)  =— 2  m  r2"/(r),  I  will 

reserve  it  to  my  next  communication. 
When  V  =  Sw 

let  V'=Sw 


1 


•(*  -/-  uf  +  (y  -  g  -  /3)2  +  (z  -  h  -  yf 

a,  /3,  y  being  the  increments  of/5  g3  and  h. 

Now  if  we  put  a{x  —f)  +  /3  (3/  —  g)  +  y  (z  —  h)  —  6,  a2 

+  /32  +  y2  =  8%  and  expand  V,  there  results 

_.,      -,-     /  1    2e-82       1.3  (2s-82)2        0     \ 
W  =  V  +  Zm(j  —^~  +  —        ra         +  &c.) 

~V  +  2'W1      2r^"+    2  ? 

We  have  obtained  our  reductions  by  introducing  the  results 
of  symmetry.  Thus  the  coefficient  of  82  is  zero.  By  pro- 
ceeding a  step  further,  we  get 

,1.3.5.7    16 14   ,    .      \ 


Theory  of  Molecular  Action  according  to  Newton's  Law.  205 

T  \8  r5        12  r5 

+  !<*  a*  («  -/)3  +  ffl  (y-g)*  +  y4  (*-A)4  +  6a»j3«  (x  -/)«  (y-g)2+&c.  1 

105   6  fr  -/)«  (y  -  g)«  («»  |3*  +  «*  y*  +  /32  y2)      &    T 

Now  the  hypothesis  of  symmetry,  from  which  we  have  re- 
duced the  results  by  making 

v  m  (x  -ff         1     v        r2  fi 

imposes  further  the  condition  that  V —  V  is  a  function  of  8 
only,  independent  of  a,  /3  and  y.     Consequently, 

2       205  /(x  -/)«  (g4+i84  +  y4)  +  6  (x-/)»  Q/-g)2i(«2/32  +  a2  ?2  +  /32y2  \ 
24   \  r»  / 

24  r9 

Hence  we  obtain  the  equation 

This  equation  is  of  considerable  importance.  The  method 
by  which  we  have  obtained  it  appears  to  be  totally  different 
from  the  ordinary  methods,  such  as  that  employed  by  Cauchy, 
Exercises,  3.  201. 

By  substitution 

The  coefficient  of  S4  depends  on  the  value  of 

But 

r4  =  (*  -/J4  + ■  (*  -  g)4  +  (z-h)4  +  2  (x  -/)«  (y  -  £)2 
+  2  (*  -/)»  (z  -  hf  +  2  (y  -  jtf  {*  -  hf 
...  3  £  **(*—/)*  _  ^  ^  __  6  j  m{x~ff{y-gY 

=  S^-2S?l^l4(byA.)) 
Hence  the  coefficient  of  84  is  zero. 


206     Prof.  Kelland's  Reply  to  some  Objections  against  the 

So  far,  then,  as  we  have  proceeded,  we  have  obtained,  as 
our  result,  that  V  is  constant.  We  have  thus  strengthened 
the  argument,  if  any  exists,  based  on  the  neutrality  of  the 
equilibrium.  But  what  is  the  argument?  Mr.  Earnshaw 
says  (Art.  8),  "  the  displacements  of  particles  placed  in  such 
positions  as  those  here  considered  would  not  bring  into  action 
any  forces  of  restoration ;  on  which  account  the  particles 
would  not  vibrate."     Mr.  O'Brien  says,  too,  "  I  have  shown 

that  if  such  be  the  case  the  whole  universe  is  in  a 

state  of  neuter  equilibrium."  [Phil.  Mag.  June,  p.  487.]  The 
only  shadow  of  an  argument  contained  in  these  quotations 
exists  in  the  words  "on  which  account  the  particles  would 
not  vibrate."  What  would  they  do  then?  and  why?  It 
really  is  hard  that  I  should  be  obliged  to  make  the  objection's 
and  answer  them  too.  I  hope  Mr.  Earnshaw  will  point  out, 
in  a  future  communication,  whereon  he  supposes  the  in- 
ference to  hang.  So  far  as  is  stated  nothing  more  appears 
than  this :  a  particle  is  moved,  no  instantaneous  force  is  put 
in  play  by  the  motion ;  therefore  the  particle  cannot  vibrate. 
Now  to  this  argument  we  reply, — 1st,  that  the  statement  em- 
bodies a  proposition  which  is  very  difficult  of  proof:  for 
although  the  particle  receives  no  instantaneous  force,  it  cer- 
tainly communicates  one  to  the  adjacent  molecules.  On  those 
in  advance  it  acts  more  powerfully,  on  those  behind  less  so, 
than  when  in  its  position  of  rest.  Motion  will  therefore  ensue. 
Whether  the  particles  will  vibrate  or  not  we  do  not  affirm ; 
the  onus  of  proving  that  they  will  not,  rests  with  those  who 
make  the  assertion.  But  2nd,  suppose  it  could  be  proved 
that  the  particles  will  not  vibrate,  what  follows?  I  repeat  that 
we  do  not  attempt  to  explain  how  vibrations  are  generated. 
It  is  not  to  be  conceived  that  the  motion  of  a  single  particle 
should  produce  a  system  of  transverse  vibrations;  and  he  who 
rejects  every  hypothesis  which  will  not  admit  such  to  be  the 
case,  excludes  virtually  (if  I  mistake  not)  the  possibility  of  the 
existence  of  such  vibrations.  All  that  can  be  made  to  follow 
from  the  above  inference,  therefore,  appears  to  be,  that  the 
motion  of  a  single  particle  cannot  put  in  play  a  system  of  vi- 
brations. This  is  a  very  different  thing  indeed  from  what  is 
supposed  to  be  made  out  by  it,  viz.  "  that  the  constitution  of 
such  a  medium  is  incapable  of  transmitting  light,  a  phaenome- 
non  due  to  vibration."  When  it  shall  have  been  shown  to  be 
incapable  of  transmitting  vibrations,  it  will  be  time  to  reject 
it;  but  nothing  of  the  kind  has  as  yet  been  attempted. 

c.  From  what  has  preceded,  it  will  be  evident  that  we  con- 
ceive the  constitution  of  media  to  be  such  that  the  equilibrium 
is  of  the  kind  technically  called  neuter ;  yet  as  we  are  desirous 


Theory  of  Molecular  Action  according  to  Newton's  Law.  207 

of  saying  a  few  words  relative  to  the  argument  actually  insisted 
on  by  Mr.  Earnshaw,  we  propose  to  examine  briefly  the  con- 
trary case. 

Let  us  suppose  the  medium  unsymmetrical ;  and  let  us 
further  conceive  (which  by  no  means  necessarily  follows)  that 

cPV    d?V  d?V 

-T75J    -r-n  and  -=T5  are  not  zero.     Then,  as  Mr.  Earnshaw 

dfz     dg*  dhl 

has  proved  (Art.  12),  there  is  at  least  one  direction  in  which, 
if  a  particle  be  moved,  the  immediate  tendency  is  to  cause  it 
to  recede  further  from  its  position  of  rest.  The  consequence 
will  be,  either  that  the  other  particles  by  their  motion  tend  to 
stop  it,  or  that  its  motion  continues.  We  have  no  hesitation 
in  affirming  that  the  former  is  the  case.  If  all  the  particles 
commence  to  move  in  the  same  direction,  the  principle  of  the 
conservation  of  the  motion  of  the  centre  of  gravity  will  be  vio- 
lated. If,  on  the  contrary,  some  move  in  one  direction,  some 
in  the  opposite,  there  must  be  vibration  unless  it  can  be  shown 
that  the  particles  pass  each  other.  In  the  latter  case  there 
would  be  perpetual  interchange  of  place  amongst  the  particles. 
This  is  certainly  very  unlikely :  but  even  now  admitting  the 
worst  we  can  conceive,  the  possibility  of  such  a  system  is  not 
disproved.  As  it  stands  at  present,  I  am  disposed  to  think 
that  the  objections,  based  on  a  want  of  stability,  have  rather 
strengthened  than  undermined  the  hypothesis  of  the  inverse 
square  of  the  distance.  The  fact,  that  in  a  medium  of  sym- 
metry the  equilibrium  is  neuter,  is  a  very  strong  one  in  favour 
of  the  theory.  But  for  this  it  might  have  required  some  violent 
effort  to  move  a  particle  at  all :  as  it  is,  a  very  slight  force  will 
cause  motion,  so  that  the  medium  possesses  the  character  of 
molecular  non-resistance.  We  do  not  doubt,  however,  that 
there  are  some  difficulties  attending  this  as  well  as  every  other 
theory.  To  any  which  may  be  brought  forward  I  will  do 
my  best  to  reply.  I  trust  that  a  desire  for  truth,  rather  than 
a  love  of  controversy,  will  appear  in  all  that  shall  be  said  on 
either  side. 


Since  the  above  remarks  were  written  Mr.  Earnshaw  has 
resumed  his  objections,  in  a  paper  which  appears  in  the  Phi- 
losophical Magazine  for  July.  Although  all  the  arguments 
which  appear  in  that  paper  have  not  reference,  either  to  the 
want  of  fulfilment  of  the  requisites  for  vibration,  or  to  the 
instability  of  the  medium,  yet  to  avoid  confusion  I  propose  to 
reply  to  them  in  this  place.  The  consideration  of  the  other 
two  objections  placed  at  the  head  of  this  paper  will  probably 
demand  a  more  detailed  mathematical  investigation  than  could 


208  Sir  D.  Brewster  on  the  Connexion  between 

possibly  appear  within  my  present  limits,  on  which  account  I 
desire  to  reserve  it  to  a  separate  communication. 

[To  be  continued.] 

XXXVII.  On  the  Connexion  between  the  Phenomena  of  the 
Absorption  of  Light,  and  the  Colours  of  thin  Plates.  By 
Sir  David  Brewster,  K.H.,  LL.D.,  F.R.S* 
^INCE  the  phenomena  of  the  absorption  of  light  by  co- 
loured  media  began  to  be  studied  with  attention,  various 
philosophers  have  regarded  them  as  inexplicable  by  the 
theory  of  the  colours  of  thin  plates,  and  have  consequently 
regarded  Sir  Isaac  Newton's  theory  of  the  colours  of  natural 
bodies  as  either  defective  in  generality,  or  altogether  un- 
founded. Mr.  Delavalf  was  the  first  person  who  brought  an 
extensive  series  of  experiments  to  bear  upon  this  subject.  Dr. 
Thomas  Young  J  considered  it  "  impossible  to  suppose  the 
production  of  natural  colours  perfectly  identical  with  those 
of  thin  plates,"  unless  the  refractive  density  of  the  particles  of 
colouring  bodies  was  at  least  twenty  or  thirty  times  as  great 
as  that  of  glass  or  water,  which  he  considered  as  "  difficult  to 
believe  with  respect  to  any  of  their  arrangements  constituting 
the  diversities  of  material  substances."  Sir  John  Herschel 
has  expressed  a  still  more  decided  opinion  upon  this  subject. 
He  regards,  "  the  speculations  of  Newton  on  the  colours  of 
natural  bodies"  as  only  "  a  premature  generalization,"  and 
*'  limited  to  a  comparatively  narrow  range;  while  the  pha2- 
nomena  of  absorption,  to  which  he  considers  the  great  ma- 
jority of  natural  colours  as  referable,  have  always  appeared  to 
him  to  constitute  a  branch  of  photology  sui  generis  §." 

The  general  opinion  advanced  by  these  three  philosophers 
I  have  long  entertained  || ;  and  with  the  view  of  supporting 
them  I  have  analysed  a  great  variety  of  colours  which  are  ex- 
hibited by  the  juices  of  plants.  In  a  paper  "  On  the  Colours 
of  Natural  Bodies  f ,"  I  have  shown  that  the  green  colour  of 
plants,  the  most  prevalent  of  all  the  colours  of  natural  bodies, 
in  place  of  being  a  green  of  the  third  order,  as  Newton  and  his 
commentators  assert,  is  a  colour  of  no  order  whatever,  and 
having  in  its  composition  no  relation  at  all  to  the  colours  of 
thin  plates. 

*  From  the  Philosophical  Transactions,  1837,  p.  245. 
•f  Manchester  Memoirs,  vol.  ii.  p.  131. 

t  Elements  of  Nat.  Phil.  vol.  i.  p.  469,  481 ;  and  vol.  ii.  p.  638. 
§  Philosophical  Magazine,  Dec.  1833,  S.  3,  vol.  iii.  p.  401.     See  also  his 
Treatise  on  Light,  Encyc.  Metrop.,  p.  580,  581. 
||  Life  of  Newton,  chap.  vii. 
If  Edinb.  Trans.,  vol.  xii.  [Also  Phil.  Mag.,  Third  Series,  vol.  viii.  p.  468.] 


Absorption  and  the  Colours  of  TJiin  Plates.  209 

In  arriving  at  these  conclusions,  however,  and  drawing  a 
distinct  line  between  the  phaenomena  of  absorption  and  those 
of  thin  plates,  two  classes  of  facts  are  compared  under  very 
different  circumstances.  In  the  one  case  philosophers  have 
studied  in  cumulo  the  result  of  the  successive  actions  of  an 
infinite  number  of  the  colorific  particles  upon  the  intromitted 
light,  whereas  in  the  other  case  they  have  observed  only  the 
colour  of  a  single  particle,  whose  thickness  is  equal  to  that  of 
the  films  of  air,  water,  glass  and  mica  submitted  to  experi- 
ment. The  impracticability  of  combining  a  number  of  such 
films,  and  studying  their  united  action  upon  light,  was  doubt- 
less the  reason  which  prevented  natural  philosophers  from 
bringing  the  two  series  of  facts  under  the  same  conditions. 
Sir  Isaac  Newton,  indeed,  had  spoken  so  confidently  of  the 
result  of  such  a  combination,  as  to  discourage  any  attempts 
to  effect  it ;  and  it  is  a  singular  fact  that  his  successors  have 
never  called  in  question  his  bold  though  ingenious  assump- 
tion. "  If  a  thinned  or  plated  body,"  says  he,  "  which  being 
of  an  even  thickness,  appears  all  over  of  an  uniform  colour, 
shall  be  slit  into  threads  or  broken  into  fragments  of  the  same 
thickness  with  the  plate,  I  see  no  reason  why  every  thread  or 
fragment  should  not  keep  its  colour,  and  by  consequence  why 
a  heap  of  those  threads  or  fragments  should  not  constitute  a 
mass  or  powder  of  the  same  colour  which  the  plate  exhibited 
before  it  was  broken.  And  the  parts  of  all  natural  bodies 
being  like  so  many  fragments  of  a  plate,  must  on  the  same 
grounds  exhibit  the  same  colours." 

This  remarkable  opinion  I  have  often  been  desirous  to  sub- 
mit to  the  test  of  direct  experiment,  in  the  conviction  that  the 
result  would  be  different  from  what  is  here  stated ;  but  I  have 
been  baffled  in  every  attempt  to  make  such  an  experiment ; 
and  had  not  accidental  circumstances  placed  in  my  hands  two 
substances  in  which  thin  plates  were  combined  nearly  in  the 
very  manner  which  I  wished,  and  which  I  believe  had  never 
before  been  submitted  to  examination,  the  problem  might 
have  remained  long  without  a  solution. 

The  first  of  these  substances  to  which  my  attention  was 
called,  is  the  remarkable  nacreous  body  which  Mr.  Horner 
has  described  in  the  last  volume  of  the  Transactions,  and 
whose  singular  optical  properties  I  have  explained  in  a  letter 
which  accompanies  his  paper.  This  substance  consists  of 
laminae  of  considerable  transparency,  separated  by  extremely 
thin  films,  which  exhibit  in  the  most  brilliant  manner  the  co- 
lours of  thin  plates. 

In  order  to  compare  the  effect  produced  by  a  number  of 
such  films  with  that  of  a  single  film,  we  must  either  analyse 

Phil.  Mag.  S.  3.  Vol.  21 .  No.  1 37.  Sept.  1 84-2.        P 


210  Sir  D.  Brewster  on  the  Connexion  between 

the  light  reflected  and  transmitted  by  a  single  film  by  means 
of  a  fine  prism  placed  in  front  of  a  telescope,  or  examine  the 
prismatic  spectrum  produced  by  such  an  apparatus  when  it  is 
reflected  or  transmitted  by  the  film  in  question.  When  we  thus 
examine  the  reflected  tints  of  the  three  first  orders  of  colours, 
we  find  them  to  consist  of  that  part  of  the  spectrum  which 
gives  the  predominating  colour  of  the  tint  mixed  with  the  rays 
on  each  side  of  it.  The  reflected  green  of  the  third  order,  for 
example,  consists  of  the  green  part  of  the  spectrum,  bounded 
on  one  side  with  some  blue,  and  on  the  other  side  with  some 
yellow  rays,  all  the  rest  of  the  spectrum  being  wanting,  having 
passed,  as  it  were,  into  the  transmitted  beam.  In  analysing, 
therefore,  the  transmitted  beam,  its  spectrum  is  found  to  con- 
sist only  of  the  violet  and  blue,  and  the  orange  and  red  spaces, 
a  dark  band  corresponding  to  the  reflected  spectrum  separa- 
ting it  into  two  parts.  In  the  higher  orders  of  colours  the 
reflected  spectrum  consists  of  two  or  more  portions  separated 
by  perfectly  dark  bands,  while  the  transmitted  light  exhibits 
analogous  bands,  which  are  much  less  dark  in  consequence 
of  the  tint  being  diluted  with  a  portion  of  white  light.  The 
coloured  bands  of  the  reflected  spectrum  occupy  the  same 
place  among  the  fixed  lines  of  the  spectrum  as  the  dark  bands 
of  the  transmitted  one ;  and  if  the  two  spectra  were  superposed 
they  would  form  a  perfect  spectrum,  whose  rays  when  united 
would  form  white  light.  Hence  the  reflected  and  the  trans- 
mitted tints  are  complementary  to  each  other. 

When  this  analysis  is  made  with  a  highly  magnified  spec- 
trum, the  numerous  lines  of  which  are  distinctly  seen,  it 
forms  one  of  the  most  splendid  experiments  in  optics.  The 
spectrum  is  crossed  throughout  its  whole  extent  with  alternate 
dark  and  coloured  bands,  increasing  in  number  and  diminish- 
ing in  magnitude  with  the  thickness  of  the  plate  by  which  the 
tint  is  produced. 

If  we  use  a  thin  film  of  mica,  of  such  a  thickness  as  polar- 
izes the  isohite  of  the  first  order,  the  transmitted  spectrum  will 
be  crossed  by  upwards  of  three  hundred  dark  and  three  hun- 
dred luminous  bands,  thirty-four  of  each  being  included  be- 
tween the  lines  C  and  D  of  Fraunhofer,  a  space  less  than  one 
tenth  of  the  whole  spectrum. 

W7hen  we  use  polarized  light,  and  interpose  a  doubly  re- 
fracting plate,  and  subsequently  analyse  the  transmitted  beam, 
the  spectrum  is  crossed  with  an  analogous  series  of  bands, 
which  are  still  more  splendid  and  more  perfect  than  those 
given  by  a  singly  refracting  film.  The  bands  in  the  comple- 
mentary spectra  are  equally  and  perfectly  dark;  and  when 
the  tints  are  pure  as  in  calcareous  spar,  the  colours  are  nearly 


Absorption  and  the  Colours  of  Thin  Plates.  211 

identical  with  those  of  thin  plates.  Through  the  natural  faces 
of  a  rhomb  of  calcareous  spar  about  one  sixth  of  an  inch  thick, 
I  observed  in  the  space  C  D  above  mentioned  hundreds  of 
the  most  minute  lines  almost  as  sharp  and  black  as  those  in 
the  solar  spectrum. 

In  the  phaenomena  of  periodical  colours  which  we  have 
now  described,  there  are  three  peculiarities  which  demand 
our  attention.  1.  The  dark  lines  change  their  place  by  in- 
clining the  plate  which  produces  them.  2.  Two  or  more 
lines  never  coalesce  into  one,  and  one  line  of  the  series  is  never 
seen  without  all  the  rest  being  equally  visible.  3.  The  colours 
of  the  luminous  bands  in  the  complementary  spectra  are  the 
same  as  those  of  the  original  spectrum  when  the  thin  plate  is 
perfectly  colourless.  In  the  case  of  polarized  tints  this  simi- 
larity is  not  general. 

In  order  to  obtain  a  correct  idea  of  the  phaenomena  of  ab- 
sorption, I  shall  describe  those  which  are  exhibited  by  a  solid, 
&  fluid,  and  a  gaseous  body, — by  the  common  smalt  blue  glass, 
by  the  green  sap  of  vegetables,  and  by  nitrous  acid  gas. 

Dr.  Young  has  described  the  smalt  blue  glass  as  dividing 
the  spectrum  "  into  seven  distinct  portions."  I  have  given  in 
the  Edinburgh  Transactions*  rude  coloured  drawings  of  the 
effect  it  produces  on  the  spectrum,  and  Sir  John  Herschelf 
has  represented  its  action  in  a  different  manner.  Excepting 
in  the  single  circumstance  of  the  spectrum  being  divided  into 
bands,  there  appears  no  analogy  whatever  between  this  phae- 
nomenon  and  those  of  thin  plates.  The  bands  diminish  in 
number  as  the  thickness  of  the  plate  increases,  and  their  co- 
lour suffers  no  other  change  by  inclining  the  plate  but  that 
which  arises  from  the  small  increase  of  thickness  which  the 
ray  traverses.  There  is  one  remarkable  point  of  difference 
between  the  two  classes  of  phaenomena  which  requires  to  be 
specially  attended  to.  The  colours  of  some  of  the  luminous 
bands  are  not  the  same  as  those  of  the  spectrum,  and  therefore 
the  glass  has  removed  certain  colours  while  it  has  left  others 
of  exactly  the  same  refrangibility.  The  green,  for  example, 
is  changed  into  yellow  by  the  removal  of  blue  rays,  and  in 
certain  glasses  a  band,  almost  white,  is  produced.  The  co- 
lours thus  removed  are  said  to  be  absorbed;  and  by  an  exten- 
sive series  of  experiments  with  such  absorbing  substances  I 
have  been  able  to  insulate  white  light  in  the  spectrum,  which 
no  prism  can  decompose,  and  to  establish  the  existence  of  three 
equal  and  superposed  spectra  of  red,  yellow  and  blue  light. 

Analogous  phaenomena  are  exhibited  in  an  alcoholic  solu- 

*  Vol.  jx.  p.  439.  pi.  xxvii.  f  Ibid.  p.  449.  pi.  xxviii. 

P2 


212  Sir  D.  Brewster  on  the  Connexion  between 

tion  of  the  colouring  matter  of  the  green  leaves  of  vegetables. 
The  spectrum  which  it  forms  consists  of  six  luminous  bands, 
separated  by  five  dark  ones*,  and  the  phaenomena  have  the 
same  character  as  those  of  the  blue  glass. 

When  the  spectrum  is  viewed  through  nitrous  acid  gas  the 
phaenomena  are  still  more  remarkable.  While  the  gas  exerts 
a  general  absorbent  action  over  the  violet  extremity  of  the 
spectrum,  it  attacks  it  when  in  a  diluted  state  in  definite  lines 
as  sharp  and  distinct  as  those  in  the  solar  spectrum  ;  and  what 
is  still  more  important,  it  acts  upon  the  same  parts  of  light  as 
the  cause  which  produces  the  fixed  lines  in  the  sun's  spec- 
trum. In  other  respects  the  character  of  its  action  is  similar 
to  that  of  the  blue  glass  and  the  green  sap  of  plants. 

In  thus  comparing  the  phasnomena  of  absorption  with  those 
of  thin  plates,  we  find  no  connecting  link  but  that  of  giving 
a  divided  or  a  mutilated  spectrum ;  and  even  this  common 
fact  has  not  the  same  character  in  both.  In  coloured  media 
the  bands  of  light  and  darkness  have  no  fixed  relation,  as  in 
periodical  colours;  and  the  light  removed  from  the  dark  por- 
tions, as  well  as  the  tints  from  some  of  the  coloured  spaces, 
have  wholly  disappeared,  in  place  of  being  found  in  the  re- 
flected beam. 

I  have  already  mentioned,  that  by  the  aid  of  two  substances 
I  have  been  able  to  study  this  subject  under  a  new  aspect, 
and  that  the  nacreous  substance  described  by  Mr.  Horner  was 
the  one  which  first  exhibited  to  me  the  connexion  between 
absorption  and  periodical  action. 

This  substance  when  it  contains  no  thin  plates  acts  generally 
in  absorbing  the  violet  and  blue  end  of  the  spectrum;  but 
when  it  includes  within  it,  or  has  on  its  surface  thin  films 
which  act  like  thin  plates,  it  exercises  an  additional  'action 
upon  the  spectrum.  In  some  cases  when  the  thickness  of  the 
plate  is  small,  it  produces  bands  perfectly  identical  with  those 
of  thin  plates,  but  in  other  cases  the  bands  are  exactly  similar 
to  those  of  coloured  media.  In  one  specimen  I  obtained  a 
dark  and  distinct  band  in  the  orange  space  at  D,  with  another 
feint  band  in  the  red.  These  bands  were  parallel  to  the  fixed 
line  D  at  a  vertical  incidence,  but  by  inclining  the  plate  the 
bands  moved  towards  the  green  space,  and  became  inclined 
to  the  line  D.  In  a  recent  specimen  I  obtained  the  darkest 
band  in  the  green  space,  with  other  lesser  bands  of  unequal 
size  and  breadth  in  the  other  spaces,  all  of  which  moved 
along  the  spectrum,  while  new  ones  advanced  from  the  red  ex- 

*  A  full  account  of  this  experiment,  and  a  coloured  drawing  of  the  di- 
vided spectrum,  will  be  found  in  the  Edinburgh  Transactions,  vol.  xii. 


Absorption  and  the  Colours  of  Thin  Plates.  2 1 3 

tremity  during  the  inclination  of  the  plate.  In  a  third  specimen 
the  phaenomena  were  still  more  varied,  and  what  was  a  new 
feature  in  the  results,  the  colour  of  the  tints  was  changed  exactly 
as  in  the  phaenomena  of  absorption.  It  is  very  obvious  that 
these  results  are  not  produced  by  the  same  action  which  causes 
the  orange  colour  of  the  substance,  for  this  action  could  not 
vary  by  the  inclination  excepting  in  producing  a  greater  ab- 
sorption of  the  more  refrangible  rays ;  but  in  order  to  place 
this  beyond  a  doubt,  I  detached  a  film  which  had  none  of  the 
colours  of  thin  plates,  and  which,  as  I  expected,  produced' 
none  of  the  bands  above  described.  In  these  experiments 
the  nacreous  plate  was  placed  in  Canada  balsam  to  remove 
the  imperfect  smoothness  of  its  surface,  but  the  phasnomena 
were  essentially  the  same  with  plates  surrounded  by  air.  I 
now  divided  the  first  of  the  plates  above  mentioned  into  two, 
and  having  viewed  the  spectrum  through  both,  I  found  the 
principal  black  band  considerably  widened,  as  happens  with 
absorbent  media. 

When  the  light  reflected  from  the  nacreous  plates  is  ex- 
amined in  a  similar  manner,  the  division  of  the  spectrum  into 
bands  is  extremely  brilliant  and  beautiful,  and  the  phaeno- 
mena the  same ;  but  owing  to  the  light  having  entered  the 
substance  to  different  depths  before  it  was  reflected,  the  spec- 
trum is  by  no  means  complementary  to  the  one  seen  by  trans- 
mission. 

Satisfactory  as  these  experiments  are,  I  was  still  desirous 
of  obtaining  similar  results  with  perfectly  transparent  plates ; 
but  after  failing  in  every  attempt  to  combine  them,  I  thought 
of  trying  the  iridescent  films  of  decomposed  glass*.  This 
idea  succeeded  beyond  my  most  sanguine  expectations.  I 
obtained  combinations  of  films  which  gave  me  by  transmitted 
light  the  most  rich  and  splendid  colours,  surpassing  anything 
that  I  had  previously  seen  either  among  the  colours  of  nature 
or  of  art.  I  obtained  the  deepest  and  richest  blues  shading 
off  into  the  palest,  and  the  finest  reds  and  yellows,  with  all 
those  intermediate  and  mixed  tints  which  are  seen  only  in  the 
vegetable  kingdom.  The  reflected  tints  had  quite  a  different 
character.  They  possessed  all  the  brilliancy  of  metallic  re- 
flexion, like  the  colours  in  the  Diamond  Beetle  and  other  in- 
sects, and  the  tints  varying  within  a  considerable  range  were 
disposed  in  straight  lines  and  bands,  as  if  the  film  had  formed 
part  of  a  regularly  organized  bodyf. 

*  For  a  very  fine  collection  of  these  films  I  have  been  indebted  to  the 
kindness  of  Mrs.  Buckland,  theMarquis  of  Northampton,  and  Mr.Children. 

t  The  surface  of  these  films  is  beautifully  mammillated,  the  parts  that 
are  curves  on  one  side  being  concave  on  the  other. 


214  Sir  D.  Brewster  on  the  Connexion  bePweqn 

The  reflected  tints  of  course  vary  with  the  obliquity  of  the 
incident  light ;  and  at  great  incidences  the  transmitted  ones, 
however  splendid  and  varied,  all  become  pale  yellow.  When 
these  combinations  of  glass  films  are  immersed  in  a  balsam  or 
an  oil,  their  colours,  whether  transmitted  or  reflected,  all  dis- 
appear, excepting  a  pale  yellow  light  like  that  which  is  trans- 
mitted at  great  incidences.  These  facts  prove,  beyond  a 
doubt,  that  the  transmitted  colours,  though  wholly  unlike 
to  those  of  thin  plates,  are  yet  produced  by  the  same  cause, 
and  are  residuary,  and  generally  complementary  to  the  hue 
of  the  reflected  tints. 

The  analysis  of  these  colours  by  the  prism  affords  a  series 
of  most  beautiful  and  instructive  phaenomena,  and  it  is  only 
by  coloured  drawings  that  any  adequate  idea  of  them  can  be 
conveyed.  All  the  phenomena  of  coloured  media,  with  bands 
of  various  breadths  and  various  intensities  of  illumination,  are 
exhibited  in  great  perfection,  so  as  to  identify  completely  in 
this  feature  the  two  classes  of  facts.  But  what  is  still  more 
striking,  the  colours  of  the  bands  are  changed,  and  we  thus 
find  that  the  characteristic  phaenomenon  of  absorption  is  pro- 
duced by  the  action  of  thin  plates.  To  such  a  degree  indeed 
is  the  change  of  tint  carried,  that  I  have  insulated  a  white  band 
in  the  orange  part  of  the  spectrum.      9 

Notwithstanding  this  identification  of  absorption  and  pe- 
riodical action  in  their  primary  features,  there  are  two  points 
of  difference  which  separate  widely  the  two  classes  of  phaeno- 
mena :  the  first  of  these  is,  that  the  bands  and  tints  of  ab- 
sorbing media  are  not  changed  by  obliquity;  and  the  second, 
that  the  reflected  tints  are  not  visible  in  such  media.  Sir 
Isaac  Newton  endeavoured  to  remove  the  first  of  these  diffi- 
culties by  supposing  that  the  particles  of  bodies  on  which 
their  colours  depended  have  an  enormous  refractive  power ; 
and  M.  Biot  *  has  endeavoured  to  meet  it  more  effectually  by 
introducing  two  new  suppositions ;  viz.  that  the  particles  are 
capable  of  transmitting  light  only  through  their  centre  of  gra- 
vity, and  that  the  lateral  transmissions  may  be  prevented  or 
turned  aside  by  the  inflecting  forces  which  act  at  a  distance 
on  the  luminous  molecules  which  approach  them. 

These  explanations  of  the  uniformity  of  the  tints  at  all  in- 
cidences have  been  rendered  necessary,  not  perhaps  by  the 
real  difficulties  of  the  case,  but  in  consequence  of  Sir  Isaac 
Newton  and  his  followers  taking  it  for  granted  that  the  co- 
lours of  natural  bodies  were  pure  tints  of  a  particular  order. 
Hence  it  becomes  a  necessary  assumption  in  the  theory  that 

*  Traite  de  Physique,  torn.  iv.  p.  126. 


Absorption  and  the  Colours  of  Thin  Plates.  215 

the  particles  had  sizes  corresponding  to  these  pure  tints,  and 
that  the  light  which  composed  them  should  not  pass  through 
different  thicknesses  of  these  particles.  As  I  have  demon- 
strated, however,  in  a  paper  already  referred  to,  that  the  tint 
which  Newton  reckoned  one  of  the  third  order,  has  no  con- 
nexion whatever  with  that  or  with  any  other  order,  and  that 
all  other  tints  of  absorbent  media  are  in  the  same  predica- 
men;,  we  are  not  only  free  from  the  difficulty  which  embar- 
rassed Newton ;  but  it  is  actually  necessary  to  have  recourse 
to  particles  of  an  ordinary  refractive  power,  and  having  such 
forms  and  occupying  such  positions  as  will  permit  lateral 
transmissions  and  thus  produce  compound  tints,  such  as  we 
actually  observe  in  natural  bodies,  and  as  we  have  shown  to 
be  produced  by  thin  plates. 

Now  if  we  suppose  the  colouring  particles  to  be  spherical, 
or  to  have  the  form  of  plates  or  cubes,  or  other  solids  dissemi- 
nated through  the  fluid  or  solid  bodies  which  they  colour, 
the  tints  would  be  permanent  and  compound  as  we  find  them 
in  nature. 

The  second  point  of  difference  to  which  I  have  referred, 
namely,  the  absolute  disappearance  of  the  reflected  tints  in 
several  coloured  solids,  fluids,  and  gases,  is  one  of  great  mag- 
nitude. Newton  has  evaded  this  difficulty  in  his  theory ;  but 
from  the  manner  in  which  he  gets  rid  of  the  intromitted  light 
in  black  bodies,  it  is  obvious  that  he  would  ascribe  the  dis- 
appearance of  the  reflected  tints  to  their  being  "  variously 
reflected  to  and  fro  until  they  happened  to  be  stifled  and 
lost." 

As  I  shall  have  occasion  to  discuss  this  subject  experiment- 
ally in  a  paper  on  the  permanent  colours  of  natural  bodies,  I 
shall  only  state  at  present  that  I  have  succeeded  by  particular 
methods  in  rendering  reflected  tints  visible  in  many  coloured 
fluids  and  glasses,  but  1  cannot  consider  them  as  equivalent 
to  the  reflections  of  thin  plates. 

I  have  endeavoured  to  corroborate  the  views  contained  in 
the.  preceding  pages  by  a  series  of  collateral  experiments  on 
the  periodical  colours  of  polarized  light.  When  we  divide 
the  spectrum  into  bands  by  doubly  refracting  plates,  the  phae- 
nomena  are  beautiful  beyond  all  description.  If  we  dissect 
or  subdivide  the  luminous  bands  in  the  spectrum,  as  seen  by 
one  analysing  prism,  by  means  of  successive  plates  and  prisms, 
the  result  is  very  remarkable;  and  if  the  doubly  refracting, 
plates  are  inclined  to  each  other  or  to  the  incident  beam,  the 
black  bands  will  also  be  inclined  to  each  other,  and  the  lu- 
minous spaces  have  the  form  of  a  triangle  either  complete  or 
truncated  at  its  apex.     By  using  plates  of  the  same  or  of  va- 


216       On  Absorption  and  the  Colours  of  lliin  Plates. 

rious  substances  *,  and  placing  their  axes  in  different  azi- 
muths to  the  plane  of  primitive  polarization,  we  obtain  ex- 
tremely singular  spectra,  in  which  the  bands  approximate  to 
those  of  absorbing  media. 

But  there  is  another  result  of  this  class  of  experiments  to 
which  I  would  especially  call  the  attention  of  philosophers. 
The  colours  of  the  bands  thus  produced  have  no  resemblance 
to  those  of  the  original  spectrum,  so  that  the  spectrum  has 
actually  been  analysed  by  dissection.  This  effect  is  so  de- 
cided, that  even  by  a  single  subdivision  of  a  banded  spectrum 
I  have  succeeded  in  insulating  a  band  nearly  white,  and  of 
course  incapable  of  being  decomposed  by  the  prism. 

Hence  we  deduce  from  the  phenomena  of  thin  plates,  and 
polarized  tints,  the  existence  of  a  new  property  of  light,  in 
virtue  of  which  the  reflecting  force  selects,  as  it  were,  out  of 
differently  coloured  rays  of  the  same  refrangibility  rays  of  a 
particular  colour,  allowing  the  others  to  pass  into  the  trans- 
mitted beam ;  or  to  use  the  language  of  the  undulatory  theory, 
the  colour  produced  by  the  interference  of  homogeneous  pen- 
cils reflected  from  the  first  and  second  surfaces  of  thin  plates, 
is  different  from  the  colour  produced  by  the  interference  of 
the  transmitted  light  with  that  which  has  suffered  two  inter- 
nal reflexions  within  the  plate.  If,  for  example,  we  use  the 
greenish  yellow  light  of  the  spectrum  between  the  lines  D  and 
E,  the  system  of  reflected  rings  will  be  more  yellow  than  the 
transmitted  rings  towards  E,  and  more  green  than  the  same 
rings  towards  D ;  a  result,  which,  in  so  far  as  the  transmitted 
tints  are  concerned,  is  seen  in  the  colours  of  smalt  blue  glass. 

Here  then  we  have  a  principle  not  provided  for  in  either 
of  the  theories  of  light  to  which  the  phaenomena  of  absorption, 

*  I  have  constructed  apparatuses  of  this  kind  made  out  of  composite 
crystals  of  calcareous  spar,  including  one  and  more  thin  plates  of  its  own 
substance.  The  beautiful  and  apparently  capricious  tints  which  such  cry- 
stals exhibit  when  properly  cut  into  prisms,  or  when  prisms  are  applied  to 
their  surface,  are  nothing  more  than  the  luminous  bands  of  the  spectrum 
subdivided  by  one  or  more  dissections.  I  have  now  before  me  such  a  cry- 
stal, in  which  a  prism  cemented  externally  brings  out  the  spectrum,  which 
would  otherwise  have  suffered  total  internal  reflexion.  A  virtual  prism 
forming  part  of  the  rhomb  polarizes  the  incident  light,  an  included  hemi- 
trope  plate  affords  the  polarized  tints,  and  a  second  virtual  prism  analyses 
the  light  which  the  plate  transmits.  In  some  parts  of  the  rhomb  there  are 
plates  of  different  thickness,  by  which  the  luminous  bands  are  beautifully 
subdivided.  In  this  manner,  by  the  slight  aid  of  an  applied  prism,  we  are 
•furnished  with  a  complicated  optical  apparatus.  Such  a  combination, 
which  it  is  easy  to  make  artificially  by  inclosing  thin  doubly  refracting 
plates  between  prisms  of  calcareous  spar,  affords  an  ocular  explanation  of 
those  beautiful  forms  of  the  system  of'  polarized  rings  which  are  produced 
in  composite  crystals  of  calcareous  spar.  These  subdivided  bands,  indeed, 
are  portions  of  that  system  seen  obliquely  by  prismatic  refraction. 


Mr.  Earnshaw  on  Dispersion,  in  reply  to  Prof.  Powell.  217 

produced  by  nacrite,  by  decomposed  films  of  glass  and  by 
polarizing  plates,  are  distinctly  referable.  Here  also  we  have 
the  probable  cause  of  certain  remarkable  phenomena  of  di- 
chroism  in  doubly  refracting  bodies,  in  which  rays  of  the  same 
refrangibility,  but  of  different  colours,  pass  into  the  ordinary 
and  extraordinary  pencils. 
Allerly,  May  5th,  1837. 


XXXVIII.  On  the  Theory  of  the  Dispersion  of  Light;  in 
reply  to  Prof.  Powell's  Note.  By  S.  Earnshaw,  M.A., 
Cambridge*. 

T^HE  object  which  I  had  in  view  in  writing  the  letter  printed 
-*  in  your  Magazine  for  April,  was  to  show  that  the  "  op- 
probrium of  all  theories, — the  dispersion  of  light," — has  not 
yet  been  removed  from  the  undulatory  theory.  I  endeavoured 
to  accomplish  this  object  by  showing  two  things  ; — 1st,  that  a 
certain  formula,  derived  directly  from  theory,  which  was  said 
to  have  supplied  "  both  the  laws  and  the  explanation  of  the 
phenomena  of  dispersion,"  is  insufficient  for  that  purpose ; 
and  2ndly,  that  the  method  of  calculation  employed  in  com- 
piling the  tables  given  in  Professor  Powell's  book  is  a  method 
of  interpolation  only,  and  therefore  from  its  very  nature  inca- 
pable of  verifying  a  physical  theory  of  dispersion.  It  is  not 
necessary  to  repeat  the  arguments  by  which  I  endeavoured 
to  establish  these  two  points.  In  answer  to  the  former,  the 
Professor  distinctly  states  that  he  has  "long  since  discarded  " 
the  formula  animadverted  upon ;  and  therefore  I  suppose  that, 
as  far  as  that  formula  is  concerned,  I  may  consider  the  object 
of  my  letter  accomplished.  In  answer  to  the  remaining  parts 
of  my  letter,  the  Professor,  if  I  rightly  understand  his  note, 
puts  forward  three  arguments  : — 

1st.  That  Sir  W.  R.  Hamilton  has  taken  the  trouble  of 
simplifying  the  mode  of  calculation,  a  circumstance  which  im- 
plies his  approval  of  the  general  principle. 

2ndly.  That  that  "  pre-eminently  gifted  mathematician 
M.  Cauchy  "  has  considered  his  own  investigations  a  suffi- 
cient basis  for  calculation  ;  and, 

3rdly,  That  the  method  of  calculation  used  in  computing 
the  tables  "  is  surely,  at  all  events,  a  direct  deduction  from 
theory." 

Now  I  will  not  accuse  Professor  Powell  of  bringing  forward 
the  first  two  of  these  with  the  intention  of  carrying  the  dis- 
puted point  by  the  force  of  great  names;  but  if  such  had  been 
his  intention,  they  are,  as  it  seems  to  me,  better  suited  for 
*  Communicated  by  the  Author. 


218  Mr.  Earnshaw  on  Dispersion)  in  reply  to  Prof.  Powell. 

that  mode  of  argument  than  for  fair  philosophical  discussion. 
I  am  willing  to  pay  my  humble  tribute  to  the  merits  of  the 
two  eminent  philosophers  quoted;  but  the  matter  in  dispute 
between  Professor  Powell  and  myself  lying  entirely  within  the 
limits  of  my  own  reading  and  understanding,  it  is  not  likely 
that  I  shall  be  convinced  by  any  other  than  a  fair  appeal  to 
philosophical  argument. 

With  respect  to  the  Professor's  third  argument,  it  appears 
to  me  to  assume  too  much.  It  ought  to  have  been  shown 
that  theory  has  done  more  for  the  series  (upon  which  the  cal- 
culations are  founded)  than  merely  to  indicate  that  it  must 
proceed  according  to  inverse  powers  of  A ;  for  if  it  has,  not 
done  more  than  this,  it  has  in  effect  done  nothing.  But  even 
granting  that  there  is  something  meritorious  in  the  form  of 
the  suggested  series,  I  would  beg  the  Professor's  attention 
to  two  of  my  objections  which  still  remain  in  force; — 1st, 
that  the  mode  of  applying  it  to  calculation  disconnects  it  from 
theory,  by  rendering  the  method  one  of  ordinary  interpola- 
tion :  and  2ndly,  that  the  results  obtained  do  not  coincide 
sufficiently  with  experiment  to  warrant  us  in  concluding  from 
them  that  the  form  of  the  series  furnished  by  theory  is  the 
correct  one. 

Before  I  conclude  it  is  necessary  to  advert  to  two  other 
matters :  the  Professor  seems  to  consider  that  I  have  used 
him  unfairly  in  not  distinguishing  between  "  certain  earlier 
researches  "  and  those  contained  in  his  "  published  volume." 
If  the  Professor  will  turn  again  to  my  letter  (p.  309)  he  will 
there  read  that  the  errors  of  which  I  had  been  speaking,  are 
charged  only  upon  "  the  first  applications  of  the  method." 
I  trust  therefore  he  will  be  satisfied  that  I  am  not  guilty  of 
the  unfairness  of  which  he  complains,  and  have  not  committed 
those  "  remarkable  oversights  "  of  which  he  (somewhat  un- 
fairly I  think)  accuses  me.  And  with  respect  to  his  having 
discarded  his  earliest  researches, — "  the  simple  circumstance 
which  renders  all  my  elaborate  criticisms  superfluous," — I 
do  not  regard  it  as  being  by  any  means  so  fatal  to  my  letter 
as  the  Professor  seems  to  think  it  is :  for  if  he  will  do  me 
the  favour  to  refer  to  my  letter  again  he  will  find  that  the 
first  part  only  was  directed  against  the  "  superseded  re- 
searches," the  second  part  he  will  find  summed  up  in  these 
words :  "  the  methods  of  computation  employed  in  compiling 
the  tables  contained  in  the  book  referred  to  are  wholly  un- 
connected with  a  physical  theory  of  dispersion,  and  therefore 
were  they  even  coincident  with  experiment  add  nothing  to  the 
strength  of  M.  Cauchy's  theory ;  and  were  they  even  more  dis- 
cordant than  they  are  with  experiment,  tend  in  no  degree  to 


Mr.  H.  A.  Goodwin  on  a  Property  of  the  Parabola.    219 

overturn  it."  But  supposing  that  my  criticisms  upon  "  the 
published  volume"  could  be  set  aside  by  the  Professor's  aban- 
donment of  his  earliest  researches,  I  think  in  having  produced 
a  distinct  public  declaration  of  this  fact  it  has  done  service  to 
science,  and  therefore  to  that  extent  my  desire  has  been  ac- 
complished, for  it  cannot  be  said  that  there  is  in  the  published 
volume  any  statement  to  the  effect  that  those  researches  were 
to  be  considered  as  superseded  by  the  book  ;  so  far  otherwise 
indeed,  that  we  are  told  in  the  introduction  that  it  is  sent  forth 
"  partly  as  a  resume  of  previous  researches  which  have  from 
time  to  time  appeared,  and  partly  as  supplying  what  was 
wanting  to  complete  them,"  and  more  than  once  the  early  re- 
searches are  referred  to  in  terms  of  approval.  It  is  clear 
therefore  that  without  a  distinct  declaration,  such  as  my  letter 
has  drawn  forth,  neither  I  nor  any  other  person  would  have 
been  justified  in  treating  as  discarded  the  researches  in  which 
the  author  has  stated  it  to  be  his  opinion  that  "  the  refractive 
indices  are  related  to  the  lengths  of  waves,  as  nearly  as  pos- 
sible according  to  the  formula  deduced  from  M.  Cauchy's 
theory." 
August  11,  1842. 

XXXIX.  Proof  of  Professor  Wallace's  Property  of  the  Pa~ 
rabola.    By  Henry  Albert  Goodwin,  Esq.* 

To  the  Editors-  of  the  Philosophical  Magazine  and  Journal. 
Gentlemen, 
TF  the  accompanying  proof  of  Professor  Wallace's  property 
of  the  parabola  appears  to  you  to  have  any  advantage  over 
former  solutions  in  symmetry  and  conciseness,  it  is  much  at 
your  service.  My  object  in  offering  it  is  to  exemplify  the 
great  use  of  the  simple  equation  to  the  tangent,  which  I  have 
used,  and  because  the  method  employed  brings  out  the  result 
in  a  most  direct  manner. 

I  am,  Gentlemen,  yours  obediently, 
Corpus  Christi  College,                   Henry  Albert  Goodwin. 
Cambridge.  

Let  aj  a2«3  be  the  tangents  of  the  As  which  the  three  tan- 
gents make  with  the  axis  of  x.  The  equations  to  these  tan- 
gents are 

^  =  «i  *+—(!•)    3/  =  "2*+  —  (2-)      </  =  V+— (3.) 

al  ■  .■■■  a3 

(1.)  and  (2.)  intersect,  .*.  if  x1yl  be  the  coordinates  of  point 

r  •  .                                              m  ai+a9 

oi  intersection  #,  =  y,  =  m  — — — : 

«j  «2      *  ax  a2 

*  On  the  subject  of  this  paper,  see  p.  191  of  the  present  Number. — Edit. 


220  Royal  Society, 

(2.)  and  (3.)  intersect,  .\  if#2J/2  De  the  coordinates  of  point  of 

.   .  ra  a,c,  +  a3 

intersection,  x9  =  yg  =  m  — -. 

a2a3      *8  a2«3 

Hence  the  equation  to  a  line  through  the  first  point  of  in- 
tersection and  the  focus  will  be 

y  —  — —  (x— m)  —  k,(x—m)  suppose  (4.) 

and  the  corresponding  equation  to  the  line  through  the  se- 
cond point  of  intersection  and  the  focus  will  be 

y  =    — — -3-=s  k2(x— m)  suppose     (5.) 

1 — a3a,2 

7c  —k 
and  if  $  be  the  A  contained  by  these  lines,  tan  <J>  =    ■  l  ,£, 

which  by  reduction  from  (4.)  and  (5.)  manifestly  becomes 
"i-g3       (l+a22) 


tan  <p 


1  +  a^a     d+a22) 
a, — aq 


1  +  a^  «3 
Hence  <J>  is  clearly  supplementary  to  the  angle  between  tan- 
gents (1.)  and  (3.),  and  the  circle  described  about  the  A 
formed  by  the  tangents  (1.)  (2.)  (3.)  will  of  course  pass  through 
the  focus. 

XL.   Proceedings  of  Learned  Societies. 

ROYAL  SOCIETY. 
(Continued  from  p.  55.) 
May  5,  1842*   \   PAPER  was  also  read,  entitled,  "On  Fibre:" 
(Continued.)     -£*•     additional  observations.     By  Martin  Barry, 
M.D.,  F.R.S.,  Lond.  and  Ed.f 

On  examining  coagulating  blood,  the  author  finds  that  it  contains 
discs  of  two  different  kinds ;  the  one  comparatively  pale ;  the  other, 
very  red.  It  is  in  the  latter  discs  that  a  filament  is  formed  ;  and  it 
is  these  discs  which  enter  into  the  formation  of  the  clot ;  the  former, 
or  the  pale  discs,  being  merely  entangled  in  the  clot,  or  else  remain- 
ing in  the  serum.  He  thinks  that  the  filament  escaped  the  notice  of 
former  observers,  from  their  having  directed  their  attention  almost 
exclusively  to  the  undeveloped  discs  which  remained  in  the  serum, 

*  For  abstracts  of  the  other  papers  read  on  May  5th  and  12th,  see  p. 
54. — Edit. 

t  We  are  requested  by  Dr.  Barry  to  add  the  following  as  a  correction 
of  the  fifth  paragraph  in  the  above  abstract. 

That  the  corpuscles  of  the  blood  are  reproduced  by  means  of  parent- 
cells,  and  by  division  of  their  nuclei,  he  had  recorded,  not  as  conjectures, 
but  as  observed  facts.  (See  Phil.  Trans.,  1841,  p.  204  and  244,  pi.  xviii.) 

Dr.  Barry's  previous  observations  on  Fibre  will  be  found  in  our  last 
volume,  p.  321,  344. — Edit. 


Royal  Society.  221 

and  thus  conceived  that  the  blood-discs  are  of  subordinate  import- 
ance, and  are  not  concerned  in  the  evolution  of  fibrin. 

To  render  the  filament  distinctly  visible,  Dr.  Barry  adds  a  chemi- 
cal reagent  capable  of  removing  a  portion  of  the  red  colouring 
matter,  without  altogether  dissolving  the  filament.  He  employs  for 
this  purpose  chiefly  a  solution  of  one  part  of  nitrate  of  silver  in  120 
parts  of  distilled  water ;  and  sometimes  also  the  chromic  acid.  He 
admits  that  the  use  of  these  reagents  would,  on  account  of  their 
destructive  tendency  when  concentrated,  be  objectionable  as  proofs 
of  the  absence  of  any  visible  structure ;  but  as  the  point  to  be 
proved  is  that  a  certain  specific  structure  does  exist,  he  contends 
that  the  same  appearance  would  not  equally  result  from  the  chemi- 
cal actions  of  reagents  so  different  as  are  those  of  chrome  and  the 
salts  of  mercury  and  of  silver.  After  the  appearance  of  the  fila- 
ment, thus  brought  to  light,  has  become  familiar  to  the  eye,  it  may 
be  discerned  in  the  blood-discs,  when  coagulation  has  commenced, 
without  any  addition  whatever.  Those  blood-discs  of  the  newt, 
which  contain  filaments,  often  assume  the  form  of  flask-like  vesicles, 
the  membranes  of  which  exhibit  folds,  converging  towards  the  neck, 
where,  on  careful  examination,  a  minute  body  may  be  seen  pro- 
truding. This  body  is  the  extremity  of  the  filament  in  question,  its 
protrusion  being  occasionally  such  as  admit  of  its  remarkable  struc- 
ture being  recognised. 

The  author  proceeds  to  describe  various  appearances  which  he 
has  observed  in  the  coagulum  of  the  blood,  and  which  strongly  re- 
semble those  met  with  in  the  tissues  of  the  body,  and  are  obviously 
referable  to  a  similar  process  of  formation.  He  bears  testimony  to 
the  accuracy  of  the  delineations  of  coagulated  blood  given  by  Mr. 
Gulliver.  One  of  the  most  remarkable  phamomena  discovered  by 
the  author  in  the  coagulation  of  the  blood  is  the  evolution  of  red 
colouring  matter ;  a  change  corresponding  to  that  which  he  had 
previously  observed  to  take  place  in  the  formation  of  the  various 
structures  of  the  body  out  of  the  corpuscles  of  the  blood.  He  con- 
siders the  production  of  filaments  as  constituting  the  essential  cir- 
cumstance in  coagulation. 

He  conjectures  that  the  notched  or  granulated  fibres  noticed  in 
the  blood  by  Professor  Mayer,  may  have  been  of  the  same  kind  as 
the  flat,  grooved,  and  compound  filaments  described  by  himself;  but 
he  thinks  that,  in  that  case,  Mayer's  explanation  of  their  mode  of 
origin  must  be  erroneous ;  for  they  may  be  seen  to  be  produced  by 
a  portion  of  the  blood  not  mentioned  by  him,  namely,  the  corpus- 
cles. 

Mr.  Addison's  discovery  of  globules  in  the  uppermost  stratum  of 
inflammatory  blood,  and  of  their  influence  in  the  formation  of  the 
buffy  coat,  is  confirmed  by  Dr.  Barry,  who  remarks  that  these  glo- 
bules are  altered  red  blood-discs.  That  the  blood  corpuscles  are 
reproduced  by  means  of  parent-cells,  as  suggested  by  Mr.  Owen 
and  by  the  author,  is  confirmed  by  the  observations  of  Dr.  Remak ; 
but  the  author  had  long  ago  indicated  a  division  of  the  nucleus  as 
being  more  particularly  the  mode  of  reproduction,  not  only  of  those 


222  Royal  Society, 

corpuscles,  but  of  cells  in  general.  With  this  conjecture  the  obser- 
vations of  Reraak  on  the  blood-corpuscles  of  the  foetal  chick  fully 
accord.  Whether  the  author's  further  speculation,  namely,  that 
the  parent-cells  are  altered  red  blood-discs,  is  correct,  still  remains 
to  be  seen. 

The  phenomenon  of  the  "  breaking  off  short,"  or  notching  of  the 
fasciculus  of  a  voluntary  muscle  in  a  transverse  cleavage  of  the 
fibre,  is  regarded  by  Dr.  Barry  as  a  natural  consequence  of  the  in- 
terlacing of  the  larger  spirals,  which  he  has  described  in  a  former 
paper ;  the  fracture,  in  proceeding  directly  across  the  fasciculus, 
taking  the  direction  in  which  there  is  least  resistance. 

The  position  of  the  filament  in  the  blood-corpuscle  is  represented 
as  bearing  a  striking  resemblance  to  that  of  the  young  in  the  ovum 
of  certain  intestinal  worms,  the  filaments  of  which  are  reproduced 
by  spontaneous  division.  The  author  subjoins  the  following  quaere, 
"  Is  the  blood-corpuscle  to  be  regarded  as  an  ovum  ?" 

May  12. — The  following  papers  were  read,  viz.->- 

"  Barometrical  Observations,  showing  the  effect  of  the  Direc- 
tion of  the  Wind  on  the  Difference  between  distant  Barometers." 
By  Lieut.-Colonel  Philip  Yorke,  S.  F.  Guards.  Communicated  by 
Lieut.-Colonel  Sabine,  R.A.,  F.R.S.,  &c. 

The  author  institutes  a  comparison  between  the  barometric  heights 
as  observed  at  the  Apartments  of  the  Royal  Society,  and  at  his  house 
in  Herefordshire,  in  the  neighbourhood  of  Ross,  with  a  view  to  as- 
certain the  influence  of  prevailing  winds  on  the  atmospheric  pressure. 
The  barometers  thus  compared  together  were  of  the  same  construc- 
tion, and  by  Ihe  same  maker;  and  the  times  of  observation,  namely 
nine  o'clock  a.m.  and  three  o'clock  p.m.,  were  the  same  at  both  places, 
the  distance  between  which  is  1 1 0  miles  in  longitude,  and  about  20  in 
latitude.  The  degree  of  accordance  in  the  march  of  the  two  barome- 
ters is  exhibited  by  that  of  curves  traced  on  three  sheets  accom- 
panying the  paper.  The  results  are  given  in  eight  tables.  The  au- 
thor agrees  with  Schubler  in  ascribing  the  currents  prevailing  in  the 
atmosphere  to  the  variable  relations  of  heating  and  cooling  which 
obtains  between  the  Atlantic  Ocean  and  the  continent  of  Europe  at 
different  seasons ;  the  facts  ascertained  by  the  series  of  observations 
here  presented  being  in  accordance  with  that  hypothesis.  If  the 
northerly  and  westerly  winds  in  England  be  partly  the  effect  of  the 
expansion  of  the  air  on  the  continent,  then  the  barometer  which  is 
nearest  to  the  continent,  or  in  this  instance  that  at  London,  ought 
to  be  relatively  more  depressed  than  the  one  more  distant;  or  if 
the  southerly  and  easterly  winds  be  regarded  as  proceeding  to  the 
ocean,  then,  for  a  similar  reason,  the  barometer  nearest  to  the  ocean 
ought  to  be  relatively  depressed ;  and  that  both  these  effects  are 
produced,  is  shown  by  the  tables.  This  view  of  the  subject  also, 
the  author  remarks,  is  corroborated  by  Raymond's  observations, 
detailed  in  his  memoir  on  the  determination  of  the  height  of  Cler- 
mont Ferrand,  from  which  it  appears  that  with  the  north  winds,  the 
southern  barometer  was  most  depressed ;  while  the  reverse  occurred 
with  the  southerly  winds. 


Royal  Society.  223 

May  26. — A  paper  was  in  part  read,  entitled,  "  On  the  Transpa- 
rency of  the  Atmosphere,  and  the  Law  of  Extinction  of  the  Solar 
Rays  in  passing  through  it."  By  James  D.  Forbes,  Esq.,  F.R.S., 
Sec.  R.S.  Edinb.,  Professor  of  Natural  Philosophy  in  the  University 
of  Edinburgh. 

June  2. — The  reading  of  Prof.  Forbes's  paper  was  resumed  and 
concluded. 

This  paper  is  divided  into  seven  sections.  In  the  first,  the  qua- 
lities of  heat  and  light  are  considered  in  as  far  as  they  modify  the 
comparability  and  absolute  nature  of  our  measures  of  the  influence 
of  the  solar  rays.  All  instruments,  whether  called  Tfiermometers, 
Photometers,  or  Actinometers,  measure  but  the  peculiar  effect  to  which 
their  construction  renders  them  sensible,  but  are  incompetent  to 
give  absolute  measures  of  either  heat  or  light. 

The  second  section  treats  of  the  history  of  the  problem  of  the  law 
and  measure  of  extinction  of  the  solar  rays  in  passing  through  the 
atmosphere  of  the  earth  in  clear  weather.  The  labours  of  Bouguer, 
Lambert,  De  Saussure,  Leslie,  Herschel,  Kamtz  and  Pouillet  are 
successively  passed  under  review,  and  their  instrumental  methods 
considered. 

In  the  third  section,  a  mathematical  problem  of  considerable  dif- 
ficulty and  interest  is  investigated ;  principally  after  the  manner  of 
Laplace.  It  consists  in  the  determination  of  the  length  of  the  path 
and  the  mass  of  air  which  a  ray  of  light  must  traverse  in  passing 
through  the  earth's  atmosphere  at  every  different  angle  of  obliquity. 
The  author  determines  the  numerical  value  of  these  quantities  for 
all  angles  of  incidence  from  0°  to  90°. 

The  fourth  section  contains  an  account  of  the  observations  made 
by  the  author  in  conjunction  with  Professor  Kamtz  in  1832.  These 
were  conducted  in  1832  at  the  top  and  bottom  of  the  Faulhorn,  a 
mountain  of  the  canton  of  Berne  in  Switzerland.  The  lower  station 
was  Brientz,  and  the  intercepted  stratum  of  air  had  6800  English 
feet  of  thickness,  corresponding  in  its  weight  to  about  one-fourth  of 
the  entire  atmosphere.  Frequent  observations  were  simultaneously 
made  with  the  actinometer  and  other  meteorological  instruments  at 
both  stations,  and  the  loss  of  solar  heat  in  passing  through  the  in- 
tervening mass  of  air  was  thus  directly  determined. 

In  the  fifth  section,  the  observations  made  from  sunrise  to  sunset, 
on  one  peculiarly  favourable  day  (the  25th  September,  1832),  are 
carefully  analysed;  and  from  the  absorption  at  various  obliquities, 
the  law  of  extinction  in  the  atmosphere,  within  the  limits  of  obser- 
vation, is  attempted  to  be  deduced. 

The  sixth  and  seventh  sections  include  the  results  of  similar,  but 
less  perfect  observations  in  1832  and  in  1841. 

From  the  facts  and  reasonings  of  this  paper,  the  author  deduces, 
on  the  whole,  the  following  conclusions : — 

1.  The  absorption  of  the  solar  rays  by  the  strata  of  air  to  which 
we  have  immediate  access  is  considerable  in  amount  for  even  mo- 
derate thicknesses. 

2.  The  diurnal  curve  of  solar  intensity  has,  even  in  its  most  nor- 


224  Royal  Society. 

mal  state,  several  inflections  ;  and  its  character  depends  materially 
on  the  elevation  of  the  point  of  observation. 

3.  The  approximations  to  the  value  of  extra- atmospheric  radia- 
tion, on  the  hypothesis  of  a  geometrical  diminution  of  intensity,  are 
inaccurate. 

4.  The  tendency  to  absorption  through  increasing  thicknesses  of 
air  is  a  diminishing  one ;  and  in  point  of  fact,  the  absorption  almost 
certainly  reaches  a  limit  beyond  which  no  further  loss  will  take 
place  by  an  increased  thickness  of  similar  atmospheric  ingredients. 
The  residual  heat,  tested  by  the  absorption  into  a  blue  liquor,  may 
amount  to  between  half  and  a  third  of  that  which  reaches  the  sur- 
face of  the  earth  after  a  vertical  transmission  through  a  clear  at- 
mosphere. 

5.  The  law  of  absorption  in  a  clear  and  dry  atmosphere,  equiva- 
lent to  between  one  and  four  thicknesses  of  the  mass  of  air  traversed 
vertically,  may  be  represented,  within  those  limits,  by  an  intensity 
diminishing  in  a  geometrical  progression,  having  for  its  limit  the 
value  already  mentioned.  Hence  the  amount  of  vertical  transmis- 
sion has  always,  hitherto,  been  greatly  overrated ;  or  the  value  of 
extra-atmospheric  solar  radiation  greatly  underrated. 

6.  The  value  of  extra-atmospheric  solar  radiation,  on  the  hypo- 
thesis of  the  above  law  being  generally  true,  is  73°  of  the  actino- 
meter  marked  B  2.  The  limiting  value  of  the  solar  radiation,  after 
passing  through  an  indefinite  atmospheric  thickness,  is  15°  2'. 

1.  The  absorption,  in  passing  through  a  vertical  atmosphere  of 
760  millimeters  of  mercury,  is  such  as  to  reduce  the  incident  heat 
from  1  to  0-534. 

8.  The  physical  cause  of  this  law  of  absorption  appears  to  be 
the  non-homogeneity  of  the  incident  rays  of  heat,  which,  parting 
with  their  more  absorbable  elements,  become  continually  more  per- 
sistent in  their  character ;  as  Lambert  and  others  have  shown  to 
take  place,  when  plates  of  glass  are  interposed  between  a  source  of 
heat  and  a  thermometer. 

9.  Treating  the  observations  on  Bouguer's  hypothesis  of  a  uniform 
rate  of  extinction  to  the  intensity  of  the  incident  rays,  the  author 
obtains  for  the  value  of  the  vertically  transmitted  shares  of  solar 
heat  in  the  entire  atmosphere, — 

By  the  relative  intensities  at  Brientz  and  the  Faulhorn...  0*6842 
By  the  observations  at  the  Faulhorn  alone, — 

First  method 0*6848 

Second  method 0*7544 

By  the  observations  at  Brientz  alone, — 

First  method 0*7602  ' 

Second  method 0*7827 

June  9. — A  paper  was  read,  entitled,  "  On  the  Specific  Inductive 
Capacities  of  certain  Electric  Substances."  By  William  Snow  Har- 
ris, Esq.,  F.R.S. 

The  author,  pursuing  the  experimental  inquiry  suggested  by  the 
theory  of  Mr.  Faraday  relative  to  the  differences  in  specific  induc- 
tive capacity  exhibited  by  different  dialectric  substances,  instituted 


Action  of  the  Solar  Spectrum  on  Vegetable  Colours.     225 

a  series  of  experiments  for  determining  with  precision  their  compa- 
rative powers  of  insulation,  and  of  sustaining  by  induction  charges  of 
electricity.  The  substances  to  be  examined  were  cast  into  the  form 
of  circular  plates  and  furnished  on  both  their  surfaces  with  circular 
coatings  of  tinfoil  of  a  diameter  equal  to  one-half  that  of  the  plate, 
and  the  electric  intensities  were  measured  by  electrometers  of  the 
same  construction  as  those  which  he  used  in  his  former  experiments, 
and  which  he  has  described  in  his  paper*  already  published  in  the 
Philosophical  Transactions  for  1859.  The  results  are  stated  in  ta- 
bles ;  from  the  last  of  which  it  appears  that  the  inductive  capacities 
of  the  dialectric  bodies  tried,  that  of  air  being  expressed  by  unity, 
are  proportional  to  the  following  numbers : — 

Substances.  Relative  capacities. 

Air 1 

Rosin 1*77 

Pitch  1-8 

Bees' wax  1*86 

Glass  1-9 

Brimstone 1*93 

Shell-lac   1-95 

The  author,  in  conclusion,  offers  some  observations  on  the  expe- 
rimental processes  employed  in  his  investigation  ;  and  points  out 
several  circumstances  which  require  to  be  attended  to  in  order  to 
ensure  success. 

June  16. — The  following  papers  were  read,  viz. — 
1.  "  On  the  Action  of  the  Rays  of  the  Solar  Spectrum  on  Vegetable 
Colours."     By  Sir  John  F.  William  Herschel,  Bart.,  K.H.,  F.R.S. 

The  author,  having  prosecuted  the  inquiry,  the  first  steps  of  which 
he  communicated  in  a  paper  read  to  the  Royal  Society  in  February 
1 84-Ot,  relating  to  the  effects  of  the  solar  spectrum  on  the  colouring 
matter  of  the  Viola  tricolor,  and  on  the  resin  of  guaiacum,  re- 
lates, in  the  present  paper,  the  results  of  an  extensive  series  of  simi- 
lar experiments,  both  on  those  substances,  and  also  on  a  great  number 
of  vegetable  colours,  derived  from  the  petals  of  flowers,  and  the  leaves 
of  various  plants.  In  the  case  of  the  destruction  of  colour  of  the  pre- 
parations of  guaiacum,  which  takes  place  by  the  action  of  heat,  as 
well  as  by  the  less  refrangible  rays  of  light,  he  ascertained  that 
although  the  non-luminous  thermic  rays  produce  an  effect,  in  as  far 
as  they  communicate  heat,  they  are  yet  incapable  of  effecting  that 
peculiar  chemical  change  which  other  rays,  much  less  copiously  en- 
dowed with  heating  power,  produce  in  the  same  experiment.  He 
also  found  that  the  discoloration  produced  by  the  less  refrangible 
rays  is  much  accelerated  by  the  application  of  artificial  terrestrial 
heat,  whether  communicated  by  conduction  or  by  radiation  ;  while, 
on  the  other  hand,  it  is  scarcely  or  not  at  all  promoted  by  the  purely 
thermic  rays  beyond  the  spectrum,  acting  under  precisely  similar  cir- 
cumstances, and  in  an  equal  degree  of  condensation.  The  author 
proceeds  to  describe  the  photographic  effects  produced  on  papers 

[*  Noticed  in  Phil.  Mag.,  Third  Series,  vol.  xv.  p.  320— Edit.] 
[f  An  abstract  of  the  paper  here  referred  to  will  be  found  in  Phil.  Mag., 
Third  Series,  vol.  xvi.  p.  331. — Edit.] 

Phil.  Mag.  S.  3.  Vol.  21.  No.  137.  Sept.  1842.        Q 


226  Royal  Society. 

coloured  by  various  vegetable  juices,  and  afterwards  washed  with 
various  solutions.  The  action  of  solar  light  he  found  to  be  exceed- 
ingly various,  both  as  regards  its  total  intensity  and  the  distribution 
of  the  active  rays  over  the  spectrum.  He  observed,  however,  that 
the  following  peculiarities  obtain  almost  universally  in  the  species 
of  action  exerted  on  vegetable  colours. 

First,  the  action  is  positive ;  that  is  to  say,  light  destroys  colour, 
either  totally,  or  leaving  a  residual  tint,  on  which  it  has  no  further, 
or  a  very  much  slower  action  ;  thus  effecting  a  sort  of  chromatic  ana- 
lysis, in  which  two  distinct  elements  of  colour  are  separated,  by  de- 
stroying the  one  and  leaving  the  other  outstanding.  The  older  the 
paper,  or  the  tincture  with  which  it  is  stained,  the  greater  is  the 
amount  of  this  residual  tint. 

Secondly,  the  action  of  the  spectrum  is  confined,  or  nearly  so,  to 
the  region  of  it  occupied  by  the  luminous  rays,  as  contra-distinguished 
both  from  the  so-called  chemical  rays  beyond  the  violet,  (which  act 
with  chief  energy  on  argentine  compounds,  but  are  here  for  the 
most  part  ineffective,)  on  the  one  hand,  and  on  the  other,  from  the 
thermic  rays  beyond  the  red,  which  appear  to  be  totally  ineffective. 
Indeed,  the  author  has  not  hitherto  met  with  any  instance  of  the 
extension  of  this  description  of  photographic  action  on  vegetable 
colours  beyond,  or  even  quite  up  to  the  extreme  red. 

Besides  these,  the  author  also  observed  that  the  rays  which  are 
effective  in  destroying  a  given  tint,  are,  in  a  great  many  cases,  those 
whose  union  produces  a  colour  complementary  to  the  tint  destroyed, 
or  at  least  one  belonging  to  that  class  of  colours  to  which  such  com- 
plementary tint  may  be  referred.  Yellows  tending  towards  orange, 
for  example,  are  destroyed  with  more  energy  by  the  blue  rays  ;  blues 
by  the  red,  orange  and  yellow  rays ;  purples  and  pinks  by  yellow 
and  green  rays.  These  phenomena  may  be  regarded  as  separating 
the  luminous  rays  by  a  broadly  defined  line  of  chemical  distinction 
from  the  non-luminous  ;  but  whether  they  act  as  such,  or  in  virtue 
of  some  peculiar  chemical  quality  of  the  heat  which  accompanies 
them  as  heat,  is  a  point  which  the  author  considers  his  experiments 
on  guaiacum  as  leaving  rather  equivocal.  In  the  latter  alternative, 
he  observes,  chemists  must  henceforward  recognize,  in  heat  from  dif- 
ferent sources,  differences  not  simply  of  intensity,  but  also  of  quality  ; 
that  is  to  say,  not  merely  as  regards  the  strictly  chemical  changes  it 
is  capable  of  effecting  in  ingredients  subjected  to  its  influence. 

One  of  the  most  remarkable  results  of  this  inquiry  has  been  the 
discovery  of  a  process,  circumstantially  described  by  the  author,  by 
which  paper  washed  over  with  a  solution  of  ammonio-citrate  of  iron, 
dried,  and  then  washed  over  with  a  solution  of  ferro-sesquicyanuret 
of  potassium,  is  rendered  capable  of  receiving  w^th  great  rapidity  a 
positive  photographic  image ;  and  another  in  which  a  picture  nega- 
tively impressed  on  a  paper  washed  with  the  former  of  these  solu- 
tions, but  which  originally  is  faint  and  sometimes  scarcely  percep- 
tible, is  immediately  called  forth  on  being  washed  over  with  a 
neutral  solution  of  gold.  The  picture  does  not  at  once  acquire 
its  full  intensity,  but  darkens  with  great  rapidity  up  to  a  certain 
point,  when  the  resulting  photograph  attains  a  sharpness  and  per- 


Royal  Society.  227 

fection  of  detail  which  nothing  can  surpass.  To  this  process  the 
author  applies  the  name  of  Chrysotype*,  to  recall  to  mind  its  analogy 
with  the  Calotype  process  of  Mr.  Talbot,  to  which  in  its  general 
effect  it  affords  so  close  a  parallel  \. 

2.  "Experimental  Researches  on  the  Elliptic  Polarization  of 
Light."  By  the  Rev.  Baden  Powell,  M.A.,  F.R.S.,  Savilian  Pro- 
fessor of  Geometry  in  the  University  of  Oxford. 

This  paper  contains  an  experimental'investigation  of  the  pheno- 
mena of  elliptic  polarization  resulting  from  the  reflexion  of  polarized 
light  from  metallic  surfaces,  and  the  theory  on  which  they  are  ex- 
plicable ;  the  analytical  results  being  given  in  a  tabular  form,  and 
applied  to  the  cases  of  the  experiments  themselves. 

3.  "  On  the  Influence  of  the  Moon  on  the  Atmospheric  Pressure, 
as  deduced  from  the  Observations  of  the  Barometer  made  at  the 
Magnetic  Observatory  at  St.  Helena."  By  Lieutenant  J.  H.  Le- 
froy,  R.A.,  late  Director  of  that  Observatory.  Communicated  by 
Lieut.-Col.  Sabine,  R.A.,  F.R.S. 

In  order  to  determine  the  dependence  of  the  barometric  pressure 
on  lunar  influence,  the  author  arranges  all  the  two-hourly  observa- 
tions in  each  lunar  month  with  relation  to  the  time  of  the  moon's 
passing  the  meridian;  entering  in  one  column  the  observation  of  each 
day  nearest  to  the  meridian  passage,  whether  before  or  after ;  and  en- 
tering in  separate  columns  those  corresponding  to  two  hours,  four 
hours,  six  hours,  &c,  before  and  also  after  that  observation.  The 
monthly  means  at  every  two  hours  from  the  meridian  passage  are 
then  taken ;  and  again,  the  means  at  the  same  intervals,  for  each 
three  months  from  September  1840  to  December  1841.  From  the 
results  thus  obtained  the  author  states  that  it  appears  that  the  moon's 
passage  over  both  the  inferior  and  superior  meridian  produces  a 
slight  increase  of  pressure ;  a  maximum  in  the  curve  occurring  at 
both  (that  of  the  latter  being  slightly  the  greater),  while  the  minima 
correspond  to  the  moon's  rising  or  setting. 

It  appears  also,  that  the  rise  of  the  tides  will  not  account  for  the 
whole  amount  of  the  increase  of  pressure,  even  admitting  that  it  has 
a  tendency  to  produce  an  effect  of  that  nature.  The  times  of  max- 
ima do  not  correspond  ;  and  there  appears  to  be  no  atmospheric 
establishment.  The  pressure  is  greater  about  the  period  of  new 
moon  than  at  full  moon ;  and  greater  in  the  third  and  fourth  than 
in  the  first  and  second  quarters ;  a  result  which  agrees  with  that 
given  by  Mr.  Howard  for  the  climate  of  London.  The  observations 
of  both  years  agree  in  making  the  pressure  greater  under  the  Peri- 
gee than  under  the  Apogee.  Mr.  Howard  had  found  that  the  mean 
pressure  in  Great  Britain,  which  is  in  the  opposite  hemisphere  from 
St.  Helena,  is  greater  under  the  Apogee  than  under  the  Perigee. 

4.  "  Notices  of  the  Aurora  Australis  from  the  1st  to  the  31st  of 

»  Note  by  the  Author. — A  solution  of  silver  produces  a  like  effect,  and 
with  greater  intensity,  but  much  more  slowly.  Consequently  the  name 
Chrysotype  would  seem  less  appropriate  than  Siderotype. — J.  F.  W.  H. 

[f  Mr.  Talbot's  account  of  his  Calotype  process  appeared  in  Phil.  Mag., 
Third  Series,  vol.  xix.  p.  88, 164 — Edit.] 

Q2 


228  Royal  Irish  Academy. 

March  1841,  made  on  board  H.M.S.  Erebus;  extracted  from  the 
log-book."     By  Captain  James  Clark  Ross,  R.N.,  F.R.S. 

5.  "An  Appendix  to  a  paper  on  the  Nervous  Ganglia  of  the  Uterus, 
with  a  further  Account  of  the  Nervous  Structures  of  that  Organ." 
By  Robert  Lee,  M.D.,  F.R.S. 

After  premising  a  short  history  of  the  opinions  of  Galen,  Dr. 
William  Hunter,  Mr.  John  Hunter,  Professor  Tiedemann,  Professor 
Lobstein,  and  Professor  Osiander,  relative  to  the  existence,  course, 
and  enlargement  of  the  nerves  of  the  uterus,  the  author  adverts  to 
his  own  researches  on  this  subject,  which  commenced  with  his  dis- 
covery, in  April  1838,  of  the  trunk  of  a  large  nerve  accompanying 
the  uterine  vein,  and  of  the  great  nervous  plexus  with  which  it  was 
continuous.  Of  this  discovery  he  gave  an  account  to  the  Royal 
Society  in  a  paper  read  on  the  12th  of  December  of  the  same  year. 
In  a  subsequent  paper,  he  described  some  large  nervous  ganglia* 
situated  at  the  neck  of  the  uterus ;  and  in  the  present  appendix  he 
describes  other  nervous  structures  of  still  greater  size  which  pre- 
sented themselves  to  him,  on  a  still  more  complete  dissection  which 
lie  made  of  a  gravid  uterus  at  the  full  period  of  gestation.  It  ap- 
pears from  the  results  of  these  dissections  that  the  human  uterus 
possesses  a  great  and  extensive  system  of  nerves,  which  enlarge  du- 
ring pregnancy,  along  with  the  coats,  blood-vessels,  and  absorbents 
of  that  organ,  and  which  after  parturition  resume  their  original  con- 
dition. It  is  chiefly  through  the  influence  conveyed  by  these  nerves 
that  the  uterus  is  rendered  capable  of  performing  its  various  func- 
tions, and  by  which  sympathies  are  established  between  it  and  other 
parts  of  the  system. 

6.  "  Magnetic-term  Observations  of  the  Declination,  Inclination 
and  Total  Intensity,  made  at  the  Magnetic  Observatory  at  Prague, 
for  February,  March,  and  April  1842."  By  C.  Kreil,  Director  of 
the  Prague  Observatory.  Communicated  by  S.  Hunter  Christie,  Esq-, 
M.A.,  Sec.  R.S. 

7.  "  Magnetic  and  Meteorological  Observations  for  February 
•1842,  taken  at  the  Magnetic  Observatory  at  Madras."  Presented 
by  the  Honourable  Court  of  Directors  of  the  East  India  Company. 
Communicated  by  the  Council  of  the  Royal  Society. 

8.  "Magnetic  and  Meteorological  Observations  from  May  1841 
'to  March  1842,  made  at  the  Observatory  established  by  the  Rajah 
<of  Travancore,  at  Trevandrum,  transmitted  to  the  Royal  Society  by 
^command  of  His  Highness  the  Rajah."  By  John  Caldecott,  Esq., 
E.R.S.,  Director  of  the  Observatory  at  Trevandrum. 

ROYAL  IRISH  ACADEMY. 

[Continued  from  p.  68.] 

May  24,  1841. — Professor  MacCullagh  read  a  supplement  to  his 
paper  "  On  the  dynamical  Theory  of  Crystalline  Reflexion  and  Re- 
fraction." 

In  .his  former  paper  on  that  subject  (see  Proceedings,  9th  Dec.  1 839, 

*  :See  Phil.  Mac., Third  Series,  vol.xvi.,  p.  590 ;  and  vol.  xix.  p.  487.— 
Edit.] 


Prof.  M'CulIagh  on  Crystalline  Reflexion  anil  Refraction.  229 

Phil.  Mag.  S.  3,  vol.  xvi.  p.  229)  the  author  had  given  the  general  prin- 
ciples for  solving  all  questions  relative  to  the  propagation  of  light  in 
a  given  medium,  or  its  reflexion  and  refraction  at  the  separating  sur- 
face of  two  media ;  but  he  had  applied  them  only  to  the  common  case 
of  waves,  which  suffer  no  diminution  of  intensity  in  their  progress, 
and  in  which  the  vibration  may  be  represented  by  the  sine  or  cosine 
of  an  arc  multiplied  by  a  constant  quantity.  Some  months  after  that 
paper  was  read,  it  occurred  to  him  that  he  might  obtain  new  and 
important  results  by  substituting  in  his  differential  equations  of  mo- 
tion a  more  general  expression  for  the  integral,  that  is  (as  usual  in 
such  problems),  by  making  the  displacements  proportional  to  the 
sine  or  cosine  of  an  arc,  multiplied  by  a  negative  exponential,  of 
which  the  exponent  should  be  a  linear  function  of  the  coordinates. 
Such  vibrations  would  become  very  rapidly  insensible,  and  would 
therefore  be  fitted  to  represent  the  disturbance  which,  in  the  case 
of  total  reflexion,  takes  place  immediately  behind  the  reflecting  sur- 
face ;  and  the  law3  of  this  disturbance  being  thus  discovered,  the 
laws  of  polarization  in  the  totally  reflected  light  would  also  become 
known,  by  means  of  the  general  formulae  which  the  author  had  esta- 
blished for  all  cases  of  reflexion  at  the  common  surface  of  two  media. 

The  present  supplement  is  the  fruit  of  these  considerations.  It 
contains  the  complete  theory  of  the  new  kind  of  vibrations,  not  only 
in  ordinary  media,  but  in  doubly  refracting  crystals ;  and  also  the 
complete  discussion  of  the  laws  of  total  reflexion  at  the  first  or 
second  surface  of  a  crystal,  including,  as  a  particular  case,  the  well- 
known  empirical  formulas  of  Fresnel  for  total  reflexion  at  the  surface 
of  an  ordinary  medium. 

The  existence  of  vibrations  represented  by  an  expression  contain- 
ing a  negative  exponential  as  a  factor,  had  been  recognized  by  other 
writers,  and  was  indeed  sufficiently  indicated  by  the  phaenomenon  of 
total  reflexion ;  but  it  was  impossible  to  obtain  the  laws  of  such  vi- 
brations, so  long  as  the  general  equations  for  the  propagation  of  light 
were  unknown. 

The  method  of  deducing  these  equations  was  given  in  the  abs- 
tract of  the  author's  former  paper  (see  Proceedings,  as  above)  ;  but 
as  they  were  not  there  stated,  it  may  be  well  to  transcribe  them 
here.     If  then  we  put 

X  =  —i  —  ^l,     Y  =  ^  —  ^1,     Z=^  —  tm    .   '  .  (\) 

dz      dy  dx      dz'  dy      dx 

and  suppose  the  axes  of  coordinates  to  be  the  principal  axes  of  the 
crystal,  the  equations  in  question  may  be  thus  written : — 


(2) 


dta~ 

dZ 
dy 

dz 

diri_ 

»dX 

dz 

0dZ 
dx 

dt* 

dx 

^dX 
dy 

230  Royal  Irish  Academy. 

and  if  we  further  put 

t—^Hl  —  dJl,     M=lii— Hi,     P  —  ih.—dJHl  (3.) 

dz       dy'  dx       dz'  dy        dx' 

they  will  take  the  following  simple  form : — 

^ll  =  -  a«  X,      ?5i  =  -  fi«  Y,      £Ii  =  -  c2  Z, .     .     (4.) 
rf*«  d*2  if*  '  v    y 

in  which  it  is  remarkable  that  the  auxiliary  quantities  £„  ij„  £,  are 
exactly,  for  an  ordinary  medium,  the  components  of  the  displace- 
ment in  the  theory  of  Fresnel.  In  a  doubly  refracting  crystal,  the 
resultant  of  £p  tj,,  £,  is  perpendicular  to  the  ray,  and  comprised  in  a 
plane  passing  through  the  ray  and  the  wave  normal.  Its  amplitude, 
or  greatest  magnitude,  is  proportional  to  the  amplitude  of  the  vibra- 
tion itself,  multiplied  by  the  velocity  of  the  ray. 

The  conditions  to  be  fulfilled  at  the  separating  surface  of  two 
media  were  given  in  the  abstract  already  referred  to.  From  these 
it  follows,  that  the  resultant  of  the  quantities  £„  t)lt  £,,  projected  on 
that  surface,  is  the  same  in  both  media ;  but  the  part  perpendicular 
to  the  surface  is  not  the  same ;  whereas  the  quantities  £,  ij,  £  are 
identical  in  both.  These  assertions,  analytically  expressed,  would 
give  five  equations,  though  four  are  sufficient ;  but  it  can  be  shown 
that  any  one  of  the  equations  is  implied  in  the  other  four,  not  only 
in  the  case  of  common,  but  of  total  reflexion ;  which  is  a  very  re- 
markable circumstance,  and  a  very  strong  confirmation  of  the  theory. 

The  laws  of  double  refraction,  discovered  by  Fresnel,  but  not  legi- 
timately deduced  from  a  consistent  hypothesis,  either  by  himself  or 
any  intermediate  writer,  may  be  very  easily  obtained,  as  the  author 
has  already  shown,  from  equations  (2.),  by  assuming 

£  =  p  cos  a  sin  f ,  ij  =  p  cos  (3  sin  <p,  K—p  cos  y  sin  <p,  .  (5.) 
where  <p  =  —  (Ix  +  my  +  nz  —  st); 

A 

but  the  new  laws,  which  are  the  object  of  the  present  supplement, 
are  to  be  obtained  from  the  same  equations  by  making 

£  =  e  (p  cos  a  sin  tp  +  q  cos  a'  cos  <p)  ~\ 

y  =  e  (p  cos  /3  sin  <p  -f  q  cos  |3'  cos  p)  >• (6.) 

£  =  e  (p  cos  y  sin  <p  +  q  cos  y'  cos  tp)  J 
where  <p  has  the  same  signification  as  before,  and 

£  _  e-  —  (/*  +  9  y  +  h  z) 

the  vibrations  being  now  elliptical,  whereas  in  the  former  case  they 
were  rectilinear.  In  these  elliptic  vibrations  the  motion  depends  not 
only  on  the  distance  of  the  vibrating  particle  from  the  plane  whose 
equation  is 

lx  +  my  +  nz  =  0, (7.) 

but  also  on  its  distance^from  the  plane  expressed  by  the  equation 

fx  +  gy  +  hz  =  0; (8.) 


Prof.  M'Cullagh  on  Crystalline  Reflexion  and  Refraction.  231 

and  if  the  constants  in  the  equation  of  each  plane  denote  the  cosines 
of  the  angles  which  it  makes  with  the  coordinate  planes,  we  shall 
have  A  for  the  length  of  the  wave,  and  s  for  the  velocity  of  propaga- 
tion ;  while  the  rapidity  with  which  the  motion  is  extinguished,  in 
receding  from  the  second  plane,  will  depend  upon  the  constant  r. 
The  constants  p  and  q  may  be  any  two  conjugate  semidiameters  of 
the  ellipse  in  which  the  vibration  is  performed  ;  the  former  making, 
with  the  axes  of  coordinates,  the  angles  a,  (3,  y,  the  latter  the 
angles  a',  |3',  y'. 

As  vibrations  of  this  kind  cannot  exist  in  any  medium,  unless 
they  are  maintained  by  total  reflexion  at  its  surface,  we  shall  sup- 
pose, in  order  to  contemplate  their  laws  in  their  utmost  generality, 
that  a  crystal  is  in  contact  with  a  fluid  of  greater  refractive  power 
than  itself,  and  that  a  ray  is  incident  at  their  common  surface,  at 
such  an  angle  as  to  produce  total  reflexion.  The  question  then  is, 
the  angle  of  incidence  being  given,  to  determine  the  laws  of  the  dis- 
turbance within  the  crystal. 

The  author  finds  that  the  refraction  is  still  double,  and  that  two 
distinct  and  separable  systems  of  vibration  are  transmitted  into  the 
crystal.  He  shows  that  the  surface  of  the  crystal  itself  (the  origin 
of  coordinates  being  upon  it  at  the  point  of  incidence)  must  coincide 
with  the  plane  expressed  by  equation  (8.),  a  circumstance  which 
determines  the  three  constants  /,  g,  h.  The  plane  expressed  by 
(7.)  is  parallel  to  the  plane  of  the  refracted  wave;  and  a  normal, 
drawn  to  it  through  the  origin,  lies  in  the  plane  of  incidence,  making 
with  a  perpendicular  to  the  face  of  the  crystal  an  angle  w  which  may 
be  called  the  angle  of  refraction,  so  that  if  i  be  the  angle  of  inci- 
dence, we  have 

sin  w  =  s  sin  i, 

the  velocity  of  propagation  in  the  fluid  being  regarded  as  unity. 

To  each  refracted  wave,  or  system  of  vibration,  corresponds  a  par- 
ticular system  of  values  for  r,  s,w.  These  the  author  shows  how  to 
determine  by  means  of  the  index-surface  (the  reciprocal  of  Fresnel's 
wave-surface)  which  he  has  employed  on  other  occasions  (Transac- 
tions of  the  Academy,  vol.  xvii.  and  xviii.),  and  the  rule  which  he 
gives  for  this  purpose  affords  a  remarkable  example  of  the  use  of  the 
imaginary  roots  of  equations,  without  the  theory  of  which,  indeed,  it 
would  have  been  difficult  to  prove,  in  the  present  instance,  that  there 
are  two,  and  only  two,  refracted  waves.  Taking  a  new  system  of 
coordinates  x',  y',  z' ,  of  which  z'  is  perpendicular  to  the  surface  of 
the  crystal,  and  y'  to  the  plane  of  incidence,  while  x'  lies  in  the  in- 
tersection of  these  two  planes,  put  y'  =  0  in  the  equation  of  the 
index- surface  referred  to  those  coordinates,  the  origin  being  at  its 
centre  ;  we  shall  then  have  an  equation  of  the  fourth  degree  between 
x'  and  z',  which  will  be  the  equation  of  the  section  made  in  the  index- 
surface  by  the  plane  of  incidence.  In  this  equation  put  x'  =  sin  i, 
and  then  solve  it  for  z'.  When  i  exceeds  a  certain  angle  i',  the  four 
values  of  z'  will  be  imaginary,  and  if  they  be  denoted  by 

u±v  V  —  1,  m'  +  v'  */  —  \, 


232  Royal  Irish  Academy. 

each  pair  will  correspond  to  a  refracted  system,  and  we  shall  have, 

for  the  first, 

sin  i  sin  w  ,n  x 

tanwxs ,         s  =  — — r,         r  =  st>;     .     .     .     .     (9.) 

u  sine 

and  for  the  second, 

.       sini  .      sin  w'  ,        ,   ,  /in  \ 

tanw'  =  — r,         s'  = ,         r"  =  s'v'.  .     .     .     (10.) 

u'  sin  i 

When  i  lies  between  i'  and  a  certain  smaller  angle  i",  two  of  the 
roots  will  be  real,  and  two  imaginary.  The  real  roots  correspond 
to  waves  which  follow  the  law  of  Fresnel ;  the  imaginary  roots  give 
a  single  wave,  following  the  other  laws  just  mentioned. 

Lastly,  when  i  is  less  than  i",  all  the  roots  are  real,  the  refraction 
is  entirely  regulated  by  Fresnel's  law,  and  the  reflexion  by  the  laws 
already  discovered  and  published  by  the  author. 

If  the  crystal  be  uniaxal,  and  all  the  values  of  z'  imaginary,  the 
ordinary  wave  normal  will  coincide  with  the  axis  of  x' ;  whilst  the 
extraordinary  wave  normal  and  the  axis  of  z'  will  be  conjugate  dia- 
meters of  the  ellipse  in  which  the  index-surface  is  cut  by  the  plane 
of  incidence. 

When  a  =  b  =  c,  the  crystal  becomes  an  ordinary  medium ;  there 
is  then  only  single  refraction,  and  the  refracted  wave  is  always  per- 
pendicular to  the  axis  of  x' . 

With  regard  to  the  ellipse  in  which  the  vibrations  are  performed, 
it  may  be  worth  while  to  observe,  that  if  it  be  projected  perpendi- 
cularly on  the  plane  of  incidence,  the  projected  diameters  which  are 
parallel  to  the  surface  of  the  crystal  and  to  the  wave  plane  will,  in 
all  cases,  be  conjugate  to  each  other,  and  their  respective  lengths 
will  be  in  the  proportion  of  r  to  unity.  The  vibrations,  it  is  obvious, 
are  not  performed  in  the  plane  of  the  wave,  though  they  take  place 
without  changing  the  density  of  the  aether. 

The  new  laws  here  announced  are,  properly  speaking,  laws  of 
double  refraction,  and  are  necessary  to  complete  our  knowledge  of 
that  subject.  Between  them  and  the  laws  of  Fresnel  a  curious  ana- 
logy exists,  founded  on  the  change  of  real  into  imaginary  constants. 

The  laws  of  the  total  reflexion,  which  accompanies  the  new  kind 
of  refraction,  need  not  to  be  dwelt  upon  in  this  abstract,  as  nothing 
is  now  more  easy  than  to  form  the  equations  which  contain  them. 
In  fact,  the  difficulties  which  formerly  surrounded  the  problem  of  re- 
flexion, even  in  the  simplest  cases,  have  completely  disappeared, 
since  the  author  made  known  the  conditions  which  must  be  fulfilled 
at  the  separating  surface  of  two  media. 

In  what  precedes,  it  has  been  supposed  that  the  reflexion  and  re- 
fraction take  place  at  the  first  surface  of  the  crystal,  because  this  is 
the  more  difficult  and  complicated  of  the  two  cases  into  which  the 
question  resolves  itself.  But  it  will  usually  happen  in  practice  that 
a  ray  which  has  entered  the  crystal  will  suffer  total  reflexion  at  the 
second  surface,  while  the  new  kind  of  vibration  is  propagated  into 
the  air  without.  The  refracted  wave  will  then  be  always  perpendi- 
cular to  the  axis  of  x{ ;  the  fcwo  reflected  rays,  within  the  crystal, 


Intelligence  and  Miscellaneous  Articles.  233 

will  be  plane-polarized,  according  to  the  common  law,  but  they  will 
each  undergo  a  change  of  phase ;  and  the  vis  viva  of  the  two  rays 
together  will  be  equal  to  that  of  the  incident  ray,  the  vis  viva  being 
measured  by  the  square  of  the  amplitude  multiplied  by  the  propor- 
tional mass. 

In  conclusion,  the  author  states  a  mathematical  hypothesis,  by 
which  both  the  laws  of  dispersion,  and  those  of  the  elliptic  polariza- 
tion of  rock  crystal,  may  be  connected  with  the  laws  already  deve- 
loped. 


XLI.   Intelligence  and  Miscellaneous  Articles. 

ON  CURCUMINE.      BY  M.  VOGEL,  JUN. 

TO  obtain  the  colouring  principle  of  turmeric  root,  the  author 
treated  it,  reduced  to  powder,  repeatedly  with  boiling  water,  till  it 
nearly  ceased  to  be  coloured  by  it.  The  dried  residue,  thus  deprived 
by  water  of  its  mucilaginous,  gummy,  and  a  part  of  its  extractive 
matter,  was  repeatedly  boiled  in  portions  of  alcohol  of  specific  gra- 
vity 0*8  ;  this  dissolved  the  greater  part  of  the  colouring  matter,  but 
it  is  not  possible  to  extract  it  totally,  for  the  turmeric  powder  al- 
ways remains  coloured;  the  alcoholic  solution  is  to  be  filtered  when 
cold,  and  is  of  a  deep  brownish-red  colour.  A  portion  of  the  alco- 
hol is  to  be  separated  by  distillation,  and  the  residue  is  to  be  evapo- 
rated to  dryness  in  a  porcelain  capsule.  A  brown  viscid  mass  re- 
mains, which  retains  some  brown  extractive  matter  and  traces  of 
chloride  of  calcium,  which  is  one  of  the  salts  that  the  root  contains. 
To  separate  these  two  substances,  M.  Pelletier's  plan  was  adopted ; 
this  consists  in  treating  the  residue  with  boiling  aether,  which  be- 
comes of  a  brownish-yellow  colour.  The  extractive  matter,  which 
resists  the  action  of  the  aether,  is  of  a  black  colour,  and  attracts 
moisture  from  the  air  on  account  of  the  chloride  of  calcium  which 
it  contains.  The  decanted  aether  ought  to  be  slowly  evaporated, 
and  after  cooling,  brownish-red  fragments  remain,  which  readily 
fuse,  and  may  be  poured  into  stone  moulds  or  on  glass  plates.  In 
this  state  the  curcumine,  when  heated  to  redness  on  platina  foil, 
does  not  leave  the  smallest  residue  of  inorganic  substances. 

Attempts  were  made  to  volatilize  the  oil  which  the  odour  of  the 
curcumine  evinced  that  it  still  retained,  by  repeatedly  fusing  it ;  but 
as  this  method  did  not  succeed  perfectly,  another  was  tried,  which 
led  to  a  more  satisfactory  result. 

The  residue  obtained  by  evaporating  the  aethereal  solution  was 
dissolved  in  alcohol,  and  on  the  addition  of  an  alcoholic  solution  of 
acetate  of  lead,  a  red  precipitate  was  immediately  formed  ;  the  salt 
of  lead  was  added  as  long  as  precipitation  occurred.  When  this 
precipitate  is  washed  and  dried,  a  reddish-yellow  powder  remains, 
which  consists  of  the  yellow  colouring  matter  and  oxide  of  lead,  the 
proportion  of  the  latter  varying  from  43-67  to  56-33  per  cent.  To 
separate  the  lead,  the  powder  is  to  be  diffused  in  water  and  treated 
with  hydrosulphuric  acid  gas ;  when  the  action  of  this  is  complete, 


234-  Intelligence  and  Miscellaneous  Articles, 

the  powder,  which  has  become  of  a  deep  brown  colour,  is  to  be 
washed  and  dried  and  treated  with  boiling  aether,  which  dissolves 
the  curcumine  and  leaves  the  sulphuret  of  lead. 

By  evaporating  the  aether  slowly,  the  curcumine  is  deposited  in  thin 
laminae,  which  are  transparent  and  inodorous ;  when  reduced  to  a 
fine  powder,  curcumine  is  of  a  beautiful  yellow  colour,  which  is  more 
intense  as  the  powder  is  finer ;  in  small  laminae  it  is  of  cinnamon 
colour,  but  when  held  up  to  the  light  it  is  of  a  deep  red  colour. 

By  the  process  above  described,  about  half  an  ounce  of  curcumine 
was  obtained  from  a  pound  of  the  root ;  attempts  were  made,  but  in 
vain,  to  sublime  and  crystallize  it.  At  104°  Fahr.  it  fuses,  and  even 
at  common  temperatures  the  fine  powder  agglutinates;  it  burns 
with  a  bright  flame  accompanied  with  much  soot ;  by  exposure  to 
the  sun's  rays  it  soon  loses  its  intense  colour,  and  becomes  gradually 
of  a  yellowish- white  ;  as  curcumine  is  insoluble  in  water,  but  very 
soluble  in  alcohol  and  in  aether,  it  appears  to  resemble  the  resins. 

M.  Chevreul  had  already  stated  that  curcumine  is  composed  of  oxy- 
gen, carbon  and  hydrogen,  and  M.  Vogel  proved  that  it  contained 
no  azote,  by  fusing  it  in  a  tube  with  six  times  its  weight  of  hydrate 
of  potash,  no  trace  of  ammonia  being  obtained. 

The  mean  of  four  combustions  of  curcumine,  prepared  as  above 
described,  yielded 

Carbon  ....    69'501 
Hydrogen  . .      7*460 

Oxygen 23039— 100' 

Journal  de  Pharm.  et  de  Chim.,  Juillet  1842. 


ON  THE  ACTION  OF  ACIDS  ON  CURCUMINE.      BY  M.  VOGEL,  JUN. 

Dilute  acids  do  not  dissolve  curcumine,  but  the  concentrated  do. 
When  concentrated  sulphuric  acid  is  poured  upon  powdered  curcu- 
mine it  is  dissolved,  and  a  crimson  solution  is  obtained ;  the  red 
colour  immediately  disappears  on  the  addition  of  water,  and  green- 
ish-yellow fiocculi  are  deposited,  which  appear  to  be  pure  curcumine ; 
and  hydrochloric  and  phosphoric  acids  act  in  a  similar  manner,  but 
concentrated  acetic  acid  dissolves  it  without  effecting  any  change  in 
its  colour. 

The  action  of  nitric  acid  differs  from  the  above.  One  part  of 
curcumine  was  mixed,  in  a  porcelain  capsule,  with  two  parts  of 
concentrated  nitric  acid,  previously  diluted  with  an  equal  volume 
of  water ;  at  common  temperatures  no  change  appeared  to  take 
place,  but  when  heated  in  a  sand-bath  rapid  action  occurred,  the 
liquid  rose  in  bubbles,  so  that  it  was  requisite  to  remove  the  vessel 
from  the  fire  till  the  violence  of  the  action  ceased ;  after  this  the 
mixture  was  gently  heated  till  it  ceased  to  evolve  any  gas ;  by  this 
action  the  curcumine  is  separated  into  a  resinous  mass,  which  is  de- 
posited in  yellow  fragments,  and  a  yellow  substance,  soluble  in  wa- 
ter. The  resinous  substance,  when  repeatedly  washed  with  hot 
water,  and  afterwards  dried,  may  be  easily  reduced  to  a  fine  powder, 
which  is  yellow,  and  differs  much  from  curcumine  on  account  of  its 


Intelligence  and  Miscellaneous  Articles.  235 

peculiar  odour  and  elementary  composition.  The  yellow  substance, 
soluble  in  water,  crystallizes  from  a  concentrated  solution  in  trans- 
parent needles ;  the  quantity  formed  is  however  so  small,  and  it 
deliquesces  so  readily  in  the  air,  that  its  chemical  constitution  has 
not  been  hitherto  sufficiently  examined. 

The  above -related  experiments  on  the  action  of  acids  on  curcu- 
mine  readily  explain  how  turmeric  paper  becomes  of  a  brown  colour 
by  the  action  of  concentrated  acids,  as  well  as  by  that  of  alkalies. 
The  concentrated  acids  dissolve  the  curcumine  and  form  a  brown 
solution  with  it. — Ibid. 

[There  is,  however,  this  difference  between  the  action  of  con- 
centrated acids  and  that  of  alkaline  solutions  upon  turmeric  paper  : 
water  immediately  removes  the  colour  occasioned  by  the  former,  but 
not  that  produced  by  the  latter. — Edit.] 


ACTION  OF  ALKALINE  SUBSTANCES  ON  CURCUMINE. 

Curcumine  forms  compounds  with  the  alkalies,  which  are  very  so- 
luble in  water.  When  powdered  curcumine  is  treated  with  caustic 
potash,  a  brown  mass  results  which  is  very  soluble  in  water.  The 
curcumine  is  completely  precipitated  from  this  alkaline  solution  by 
diluted  acids.  Dilute  sulphuric  acid  occasioned  a  precipitate  in  the 
alkaline  solution,  which,  when  sufficiently  washed,  had  the  proper- 
ties of  pure  curcumine. 

According  to  the  observations  of  M.  Kartner,  it  is  not  the  alkalies 
and  alkaline  earths  only  which  change  the  yellow  colour  of  cur- 
cumine to  brown,  but  the  salts  of  lead,  uranium,  boracic  acid  and 
borates  occasion  the  same  change  in  a  greater  or  less  degree. 

The  shades  of  brown  produced  on  turmeric  paper  by  the  alkalies 
and  alkaline  earths  do  not  materially  differ  from  each  othef  ;  they 
depend  on  the  concentration  of  the  alkaline  solutions  employed. 
All  weak  acids  restore  the  original  yellow  colour  of  turmeric  paper 
browned  by  the  alkalies :  this  happens  simply  because  the  acid  com- 
bines with  the  alkali,  and  thus  decomposes  the  brown  compound  of 
the  alkali  and  curcumine.  Turmeric  paper,  browned  by  a  salt  of 
lead,  has  its  colour  very  readily  restored  by  dilute  acids ;  but  when 
altered  by  the  salts  of  uranium  the  colour  is  almost  black,  and  the 
yellow  colour  is  not  restored  until  the  paper  has  been  immersed  in 
tolerably  concentrated  acid  for  nearly  a  quarter  of  an  hour. 

A  solution  of  boracic  acid  in  alcohol  alters  turmeric  paper  to  an 
intense  orange  colour,  which  is  not  removed  by  the  action  of  any 
other  acid  ;  but  when  touched  with  ammonia,  it  assumes  for  a  short 
time  a  fine  blue  colour,  which  soon  disappears  by  the  volatilization 
of  the  ammonia.  This  blue  tint  is  also  more  or  less  shown  by  im- 
mersing paper  browned  by  boracic  acid  in  solutions  of  alkaline  sub- 
stances. 

A  solution  of  borax  renders  turmeric  paper  blackish-gray ;  the 
neutral  borates  of  potash  or  ammonia  impart  to  it  a  less  intense  gray 
colour. — Ibid. 


236  Intelligence  and  Miscellaneous  Articles. 

INSOLUBLE    SALTS    OF   THE    ALKALINE    EARTHS    DISSOLVED  BY 
HYDROCHLORATE  OF  AMMONIA  AND  CHLORIDE  OF  SODIUM. 

M.  H.  Wackenroder  states  that  sulphate  of  barytes  is  quite  inso- 
luble, but  that  the  sulphates  of  lime  and  strontia  are  soluble  in  so- 
lution of  chloride  of  sodium  ;  the  latter,  though  fslowly,  yet  com- 
pletely, and  it  is  entirely  precipitable  from  solution  by  dilute 
sulphuric  acid.  Sulphate  of  lime  dissolves  very  readily  in  solution 
of  chloride  of  sodium,  and  cannot  be  precipitated  by  dilute  sulphuric 
acid. — Ibid. 


PRODUCTION  OF  FORMIC  ACID  IN  OIL  OF  TURPENTINE. 

The  acid  reaction  of  the  oil  of  turpentine  of  commerce  is  derived 
from  formic  acid,  the  presence  of  which  is  readily  detected  in  the 
water  employed  in  its  rectification. 

According  to  M.  Weppen,  the  formation  of  this  acid  can  be  ex- 
plained only  by  the  oxidation  of  the  oil  by  contact  with  the  air. 
The  action  may  be  very  simple  : 

1  atom  of  oil  of  turpentine  ....    =5C8H  +  10O  = 

2    formic  acid =4C4H+    60 

1  ....      carbonic  acid =  1  C  20 

2    water =         4  H  +    20 

It  appeared  to  M.  Weppen  a  subject  of  interest  to  inquire  if  these 
changes  really  occurred,  or  whether  other  products  were  not  also 
formed  during  oxidation. 

As  oil  of  turpentine  oxidizes  slowly  by  exposure  to  the  air,  he 
endeavoured  to  effect  it  by  distillation  with  chromate  of  lead  and  dilute, 
sulphuric  acid.  Soon  after  ebullition  had  commenced,  the  chromate 
of  lead  was  reduced,  and  acidulous  water  distilled  with  the  oil  of 
turpentine,  in  which  the  presence  of  formic  acid  was  discoverable ; 
there  was  evolved,  at  the  same  time,  carbonic  acid  sufficient  to  ren- 
der lime-water  very  turbid.  A  question  however  arises,  whether 
this  carbonic  acid  is  really  derived  from  the  oxidation  of  the  oil  of 
turpentine,  or  is  a  secondary  product  of  the  formic  acid. — Ibid. 


PRECIPITATION  OF  CERTAIN  SALTS  BY  EXCESS  OF  ACIDS. 
BY  M.  WACKENRODER. 

It  is  an  important  circumstance  in  analysis,  that  certain  salts, 
especially  sulphates  and  oxalates,  are  precipitated  by  an  excess  of 
acid,  if  they  are  dissolved  in  other  acids,  and  especially  in  nitric  or 
hydrochloric  acid.  If,  for  example,  protosulphate  of  mercury  be 
dissolved  in  diluted  nitric  acid,  this  salt  may  be  almost  perfectly 
separated  by  the  addition  of  dilute  sulphuric  acid.  Nitric  acid, 
though  with  difficulty,  dissolves  sulphate  of  lead  completely  ;  but  if 
dilute  sulphuric  acid  be  added  to  the  solution,  the  sulphate  of  lead  is 
precipitated. 

If  a  great  excess  of  nitric  acid  or  hydrochloric  acid  holding  lead 
in  solution  have  not  the  excess  got  rid  of  either  by  saturation  or 


hitelligerice  and  Miscellaneous  Articles.  237 

evaporation,  a  small  quantity  of  oxide  of  lead  may  escape  conversion 
into  sulphuret  by  hydrosulphuric  acid  ;  and  th^  circumstance  may 
lead  to  considerable  errors. 

If  sulphuret  of  ammonium  be  added  to  a  dilute  solution  of  lead, 
sulphuret  of  lead  is  formed,  which  completely  and  readily  redissolves 
in  moderately  strong  nitric  acid  and  in  hydrochloric  acid  :  a  current 
of  hydrosulphuric  acid  gas  may  be  passed  for  a  long  time  in  these 
solutions,  especially  in  that  of  hydrochloric  acid,  without  any  effect; 
but  when  the  solution  is  diluted  with  water  black  sulphuret  of  lead 
is  precipitated,  and  after  the  addition  of  a  sufficient  quantity  of  wa- 
ter the  precipitation  is  complete. 

If  oxalic  acid  be  added  to  a  solution  of  chloride  of  strontium  acidu- 
lated with  a  sufficient  quantity  of  hydrochloric  acid,  it  does  not  be- 
come turbid ;  but  this  effect  is  produced  by  the  audition  of  a  small 
portion  of  lime. — Ibid. 


SOLUBILITY  OF  SALTS  IN   PERNITRATE  OF  MERCURY. 

M.  Wackenroder  finds  that  the  chloride,  bromide,  iodide,  cyanide, 
and  sulpho-cyanide  of  silver  are  soluble  in  pernitrate  of  mercury, 
and  that  the  ferrocyanide,  sulphuret,  and  seleniuret  of  silver  are  in- 
soluble in  the  mercurial  salt.  These  solutions  are  of  a  peculiar  and 
uncommon  nature.  For  example,  neither  nitric  acid  nor  nitrate  of 
silver  precipitates  anything  from  the  solution  of  cyanide  of  silver  in 
pernitrate  of  mercury ;  but  a  sufficient  quantity  of  hydrocyanic  or 
hydrochloric  acid,  or  metallic  chlorides,  precipitate  from  it  cyanide 
or  chloride  of  silver.  On  the  contrary,  hydrochloric  acid,  chloride 
of  sodium  or  hydrochlorate  of  ammonia,  readily  precipitate  chloride 
of  silver  from  this  solution  ;  an  excess  of  nitrate  of  silver  also  pre- 
cipitates this  salt  completely,  which  nitric  acid  does  not  precipitate. 
The  chloride,  bromide  and  iodide  of  mercury  also  dissolve  readily  in 
pernitrate  of  mercury.  Chloride  of  mercury  can  be  separated  from 
these  solutions  by  a  great  excess  only  of  chloride  of  sodium. — Ibid. 

ON  LAUROSTEARINE.  BY  M.  MARSSON. 
M.  Bonastre  found  bay-berries  to  contain  volatile  oil,  resin,  gum, 
a  fluid  fatty  matter  and  a  solid  fatty  matter,  which  last  he  called  stea- 
rine,  and  a  peculiar  crystallizable  substance  which  he  named  laurine. 
As  the  characters  assigned  to  this  last  substance  resemble  those  of 
the  stearoptens,  its  true  nature  appears  to  remain  unascertained. 
By  the  recommendation  of  M.  Liebig,  the  investigation  was  under- 
taken by  M.  Marsson,  who  discovered  a  fatty  substance  differing 
from  those  previously  known,  and  which  he  has  distinguished  by  the 
name  of  laurostearine.  It  was  obtained  by  treating  bay-berries  re- 
duced to  powder,  three  or  four  times  with  boiling  alcohol,  filtering 
it  as  quickly  as  possible,  washing  the  substance  deposited  by  cooling 
with  cold  alcohol,  purifying  it  at  first  by  fusion  in  a  salt-water 
bath,  and  filtering  while  hot,  in  order  to  separate  an  uncrystallizable 
resinous  matter,  and  afterwards  by  repeated  crystallizations  from 
alcohol. 


238  Intelligence  and  Miscellaneous  Articles. 

The  properties  of  laurostearine  are,  that  when  purified  by  alcohol 
it  is  in  the  form  of»  small  white  brilliant  silky  light  needles,  which 
are  frequently  grouped  in  the  form  of  stars.  It  is  very  difficultly 
soluble  in  cold  alcohol,  but  readily  soluble  in  strong  boiling  alcohol, 
and  is  deposited  almost  entirely  in  crystals  as  the  solution  cools. 
It  is  very  soluble  in  aether,  and  by  spontaneous  evaporation'  cry- 
stallizes, as  it  does  from  the  alcoholic  solution.  It  fuses  at  about 
112°  Fahr.,  and  on  cooling  becomes  amass  resembling  stearine,  pre- 
senting no  traces  of  a  crystalline  texture,  and  is  brittle  and  friable. 
Solution  of  potash  saponifies  it  pretty  readily,  and  forms  a  perfectly 
bright  soapy  solution  :  the  soap  separated  by  chloride  of  sodium  is 
hard,  and  yields  by  decomposition  with  acids  a  fatty  acid,  the  lauro- 
stearic  acid.  By  dry  distillation  it  yields  acroleine,  and  a  solid 
fatty  body,  crystallizable  from  aether.  It  is  formed  of 
1  atom  laurostearic  acid  =  C24  H46  O3 
1  atom  glycerine =  C3  H4  O 

1  atom  laurostearine   . .    =  C27  Hb0  O4 

Ibid* 


ON  LAUROSTEARIC  ACID.      BY  M.  MARSSON. 

This  acid  is  obtained  in  the  usual  mode,  by  the  addition  of  tartaric 
acid  to  a  hot  solution.  Soda-soap  prepared  with  pure  laurostearine 
has  the  appearance  of  a  colourless  oil,  which  on  cooling  becomes  a 
solid  crystalline  transparent  mass ;  it  is  very  soluble  in  strong  al- 
cohol, and  still  more  so  in  aether,  but  it  does  not  separate  from  either 
of  these  solvents  in  the  form  of  crystals.  Its  fusing-point  is  lower 
than  that  of  the  laurostearine  itself,  being  about  107°  Fahr. 

The  alcoholic  solution  has  a  strong  acid  reaction.  The  acid  se- 
parated in  the  mode  above  described  is  a  hydrate ;  its  formula 
is  =  C24  H48  O4,  and  that  of  the  anhydrous  acid,  combined  with 
bases  in  salts,  is  =  C24  H46  O3.  Laurostearic  acid,  therefore,  con- 
tains, in  the  state  of  hydrate,  an  atom  of  water,  which  in  salts  is 
replaced  by  an  equivalent  of  base. 

Bay-berries  contain,  besides,  a  considerable  quantity  of  fluid  green 
fatty  matter  and  resin,  but  the  last-mentioned  does  not  possess  any 
peculiar  acid  properties. — Ibid. 


ON  THE  PRESENCE  OF  ANTIMONY  IN  ARSENIOUS  ACID. 
Mi  A.  Wiggers  attempted  some  time  since  to  preserve  transpa- 
rent fragments  of  arsenious  acid  under  hydrochloric  acid.  He  did 
not  succeed  ;  the  arsenious  acid  became  gradually  cloudy  and  opake, 
but  the  examination  of  the  hydrochloric  acid  proved  that  it  con- 
tained a  considerable  quantity  of  oxide  of  antimony,  Sb203.  Seve- 
ral cases  may  occur  in  which  it  is  advantageous  to  be  aware  of 
this  admixture,  and  in  this  point  of  view  the  statement  of  the 
facts  is  not  unimportant.  A  large  portion  of  oxide  of  antimony 
sublimes  with   arsenious  acid ;   the  hydrochloric   acid   completely 

*  See  p.  167  of  the  present  Number. 


A  New  Metal — Meteorological  Observations.         239 

dissolves  this  impure  arsenious  acid,  and  yields  a  solution  from 
which  water  throws  down  a  white  precipitate*  sulphuretted  hy- 
drogen an  orange  one  of  sulphuret  of  antimony,  and  then  a  yellow 
one  of  sulphuret  of  arsenic.  Nitric  acid,  when  heated,  dissolves  the 
mixture,  leaving  a  residue  of  oxide  of  antimony  containing  arsenic 
acid,  which  is  readily  dissolved  by  hydrochloric  acid  and  by  tartaric 
acid;  and  it  forms  solutions  with  these  acids,  which  possess  all  the 
reactions  of  oxide  of  antimony.  M.  Wiggers  found  oxide  of  anti- 
mony only  in  the  vitreous  arsenious  acid  from  Andreasberg  in  the 
Hartz. — Ibid.  

DISCOVERY  OF  A  NEW  METAL. 

"  In  Part  Seventh  of  my  Journal,  which  you  will  receive  next  week, 
you  will  find  a  notice  of  the  discovery  of  a  new  metal ;  it  has  been 
named  Didym ;  it  always  accompanies  Lanthanium,  from  which  un- 
fortunately it  has  not  yet  been  separated.  All  the  researches  on 
Lanthanium,  as  well  as  those  on  Cerium,  are  erroneous." — Extract 
of  a  letter  from  Prof.  Poggendorff  to  W.  Francis. 


METEOROLOGICAL  OBSERVATIONS  FOR  JULY  1842. 

Cliiswick. — July  1 .  Heavy  rain  :  fine.  2,  3.  Very  fine.  4.  Densely  overcast. 
5.  Dry  and  windy :  showery  :  clear  and  fine.  6.  Very  fine.  7.  Overcast :  rain. 
8.  Cloudy:  heavy  rain  at  night.  9 — 11.  Fine.  12 — 14.  Cloudy  and  fine. 
15.  Fine:  dry  haze.  16.  Dry  and  clear.  17.  Slight  haze.  18.  Sultry.  19. 
Slight  rain.  20.  Fine:  showery.  21.  Densely  overcast.  22,23.  Very  fine. 
24.  Cloudless  and  hot.  25,  26.  Very  fine.  27.  Slight  rain  in  the  morning  : 
lightly  overcast  and  fine.  28.  Thunder-storm  early  in  the  morning,  most  violent 
between  five  and  six  a.m.  :  sultry  :  cloudy  and  fine.  29.  Densely  clouded  :  clear 
at  night.     30.   Cloudy  :  fine.     31.  Cloudy  and  fine  :  clear  at  night. 

Boston. — July  1.  Rain  :  rain  early  a.m.  2.  Fine :  stormy,  with  rain,  thunder 
and  lightning  p.m.  3.  Fine :  rain  r.M.  4.  Cloudy.  5.  Stormy.  6.  Windy. 
7.  Fine.  8.  Fine:  rain  p.m.  9 — 12.  Fine.  13.  Cloudy:  three  o'clock  ther- 
mometer 76°.  14—16.  Fine.  17.  Cloudy.  18.  Fine.  19.  Cloudy.  20,  21. 
Cloudy  :  rain  early  a.m.  22.  Cloudy  :  rain  p.m.  23.  Cloudy.  24.  Fine :  twelve 
o'clock  thermometer  78°.  25.  Cloudy.  26.  Fine.  27.  Fine:  rain  p.m. 
28.  Fine.     29.  Cloudy:  rain  early  a.m.     30.  Windy.     31.  Cloudy. 

Sandwick  Manse,  Orkney.— July  1,  2.  Cloudy.  3.  Cloudy:  clear.  4.  Cloudy  : 
rain.  5.  Cloudy :  showers.  6.  Cloudy.  7.  Clear:  cloudy.  8.  Rain:  fine.  9.  Bright: 
drops.  10.  Bright.  11.  Cloudy  :  rain.  12.  Bright  and  warm.  13.  Damp: 
showers.  14.  Showers.  15.  Cloudy :  drizzle.  16.  Clear.  17.  Clear:  cloudy. 
18.  Bright:  cloudy.  19.  Clear:  cloudy.  20.  Clear:  fog.  21—23.  Cloudy. 
24.  Cloudy  :  damp.  25.  Cloudy.  26,  27.  Bright.  28.  Showers.  29.  Cloudy. 
SO,  31.  Cloudy:  damp. 

Applegarlh  Manse,  Dumfries-shire. — July  1.  Showers.  2.  Wet  nearly  all  day. 
3,4.  Showery.  5.  Rain  and  wind.  6.  Fair  and  fine.  7 — 11.  Heavy  showers. 
12.  Fair  and  fine.  13.  Showery.  14.  Fair  and  fine.  15.  Very  fine.  16.  Very 
fine:  thunder.  17.  Very  fine,  but  cloudy.  18.  Showers.  19 — 21.  Fair  and 
fine.  22 — 24.  Very  fine.  25.  Very  fine  :  sultry.  26.  Very  fine  :  cloudy.  27. 
Cool  and  cloudy.  28.  Cool  but  fine.  29.  Cloudy  and  threatening.  SO,  31. 
Very  fine. 

Sun  shone  out  30  days.     Rain  fell  12  days.      Thunder  1. 

Wind  North-north-east  1  day.  North-east  2  days.  East  4  days.  South-east 
1  day.  South-south-east  1  day.  South  4  days.  South-west  1  day.  West-south- 
west 2  days.  West  9  days.  West-north-west  1  day.  North-west  3  days.  North- 
north-west  2  days. 

Calm  1 3  days.  Moderate  8  days.  Brisk  6  days.  Strong  breeze  3  days.  Boiste- 
rous 1  day. 


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THE 

LONDON,  EDINBURGH  and  DUBLIN 

PHILOSOPHICAL  MAGAZINE 

AND 

JOURNAL   OF   SCIENCE. 


[THIRD  SERIES.] 


OCTOBER   1842. 


XLII.     Contributions  to  the  Minute  Anatomy  of  Animals.   By 
George  Gulliver,  F.R.S.,  fyc.  fyc. — No.  IV.* 

On  the  Structure  of  Fibrinous  Exudations  or  False  Membranes. 

\  S  mentioned  in  the  last  Number  of  the  Philosophical 
**•  Magazine,  p.  171,  in  false  membranes,  resulting  from 
inflammation,  the  structure  is  frequently  identical  with  that  of 
fibrine  which  has  coagulated  within  or  out  of  the  body  simply 
from  rest.  In  friable  exudations,  as  I  have  noticed  in  Ger- 
ber's  Anatomy,  p.  29-30,  fig.  234,  the  corpuscles  approach 
pretty  nearly  in  number  and  appearance  to  those  of  pus,  ex- 
cept that  the  former  are  commonly  more  loosein  texture  than 
the  4atter.  In  these  exudations  too  the  fibrils  are  now  and 
then  not  visible,  though  they  may  often  be  seen  clearly  enough, 
and  the  minute  molecules  are  generally  very  abundant,  yet 
occasionally  scanty,  and  sometimes  altogether  absent,  or  at 
least  not  recognizable- 

The  figures  in  Gerber's  Anatomy  (244-251)  are  tolerably 
good  representations  of  the  fibrils  and  corpuscles  which  may 
be  commonly  seen  in  clots  of  fibrine.  The  fault  of  some  of 
those  drawings  is  that  the  fibrils  are  depicted  too  forcibly,  and 
without  that  softness  which  they  present  when  viewed  in  a 
clear  transmitted  light.  Indeed,  these  fibrils  often  form  a 
network  so  extremely  delicate  that  it  must  be  a  matter  of 
some  difficulty  to  get  it  struck  off  satisfactorily,  even  if  the 
drawings  are  made  with  accuracy ;  and  the  same  remark  is 
applicable  to  the  more  straight  and  parallel  arrangement 
which  these  fibrils  often  assume. 

The  structure  of  false  membranes  will  now  be  illustrated 

*  Communicated  by  the  Author,  August  26, 1842.  No.  III.  will  be  found 
in  our  last  Number,  p.  168. 

Phil.  Mag.  S.  3.  Vol.  21.  No.  138.  Oct.  1842.         R 


242 


Mr.  Gulliver's  Contributions  to  the 


by  examples.     All  the  figures  are  magnified  about  800  dia- 
meters. 

Case  1. — A  soldier,  aged  22,  72nd  Regiment,  was  admitted 
into  hospital  with  pulmonary  consumption,  on  the  25th  of 
January,  and  died  February  4th,  1842.  Thirty-six  hours  pre- 
vious to  death  he  had  pneuma- thorax,  the  .air  having  escaped 
through  an  opening  leading  from  a  superficial  vomica  to  the 
cavity  of  the  pleura.  The  lungs  contained  several  vomicae 
filled  with  what  is  commonly  called  softened  tubercle,  and  lined 
with  the  very  common  kind  of  friable  and  whitish  false  mem- 
brane. The  surface  of  the  pulmonary  pleura  at  a  distance 
from  the  opening  was  covered  with  a  rather  thin  and  tough 
false  membrane,  and  on  the  pleura  nearer  to  the  opening  was 
a  more  soft  and  friable  exudation. 


Fig.  1. 


Fig.  2. 


Fig.  1.  The  structure  of  the  toughish  false  membrane  just 
mentioned,  made  up  of  fibrils  similar  to  those  in  clots  of  fibrine 
either  coagulated  within  or  out  of  the  body.  At  A'a  portion 
of  the  free  surface  is  shown,  and  at  B  a  portion  of  the  attached 
or  pulmonary  surface.  Several  very  minute  molecules  per- 
vade the  false  membrane ;  at  B  there  is  an  obscure  appear- 
ance of  corpuscles  among  the  fibrils,  and  with  the  aid  of  acetic 
acid  these  corpuscles  were  clearly  exposed. 

Fig.  2.  The  softer  exudation  from  the  same  pleura.  In 
the  upper  part  of  the  figure  the  corpuscles  are  held  together 
by  an  amorphous  clot;  just  below  several  of  them  are  floating 
free  in  the  serum,  and  at  the  bottom  of  the  figure  their  nuclei 
are  clearly  exposed  by  acetic  acid.  There  were  no  minute 
molecules  either  free  or  in  the  clot,  though  some  of  them  were 
observed  in  and  on  a  few  of  the  corpuscles.  Compare  this 
with  the  friable  exudation,  fi  g.  5,  in  which  themolecules 
were  remarkably  abundant. 


Minute  Anatomy  of  Animals. — No.  IV. 
Fig.  3.  Fig.  4. 


243 


Fig.  3.  Structure  of  the  friable  false  membrane  lining  a 
vomica  of  the  same  lung.  In  the  upper  part  of  the  figure  the 
corpuscles  are  connected  by  a  clot  which  is  pervaded  by  granu- 
lar matter.  Lower  down  are  several  free  corpuscles,  a  few  of 
which  are  perhaps  altered  epithelial  cells,  together  with  smaller 
objects,  some  of  which  may  be  free  nuclei  or  nucleoli.  At 
the  bottom  of  the  figure  the  effect  of  acetic  acid  on  the  cor- 
puscles is  shown  ;  it  did  not  produce  any  ropiness  or  preci- 
pitate in  the  matter.  The  pulpy  matter  contained  in  the 
same  vomica  was  composed  of  corpuscles  like  those  in  the 
figure,  but  with  a  larger  proportion  of  granular  matter. 

Case  2. — A  man,  aged  41,  had  an  old  dropsy  of  the  belly,  of 
which  he  died  five  days  after  tapping.  The  intestines  were 
connected  together  by  coagulated  lymph,  which  in  some 
places  extended  in  the  form  of  a  thin  whitish  and  semitrans- 
parent  membrane  from  one  convolution  of  the  large  intestine 
to  another,  being  in  parts  very  thin  and  pellucid,  and  thicker, 
more  opake,  and  white  at  intervals. 

Fig.  4.  Structure  of  the  false  membrane  last  mentioned. 
A,  corpuscles  and  very  minute  molecules  in  a  network  of  de- 
licate fibrils  at  the  edge  of  a  fragment  of  the  exudation.  B 
and  C,  from  a  transparent  pellicle-like  part ;  at  B  the  fibrils 
present  a  parallel  arrangement,  and  some  of  them  appear 
granulated ;  but  they  are  commonly  smooth,  semitransparent, 
and  apparently  cylindrical.  C,  some  isolated  molecules  of 
extreme  delicacy  and  minuteness;  they  were  rather  fainter 
than  here  shown.  D  D,  from  thicker  parts  of  the  exudation 
in  which  no  distinct  structure  is  apparent.  All  the  objects 
represented  in  this  figure  were  occasionally  seen  in  different 
parts  of  the  same  fragment  of  the  false  membrane,  and  some- 
times even  in  one  field  of  vision.  Compare  the  fibrils  and 
corpuscles  with  those  which  I  have  formerly  depicted  in  a 

R  2 


244 


Mr.,  GuWiver's  Contributions  to  the 


false  membrane,  (Gerber's  Anat.,  fig.  272),  and  the  parallel 
arrangement  of  the  fibrils  with  the  same  appearance  in  fibrine 
obtained  from  blood  out  of  the  body  (I.  c.  fig.  246). 

Case  3. — A  child  18  days  old  died  of  inflammation  of  the 
peritoneum,  on  the  surface  of  which  was  some  friable  coagu- 
lated lymph. 

Fig.  5.  Fia.  6. 


Fig.  5.  The  exudation  just  mentioned.  There  are  some 
corpuscles,  and  an  abundance  of  minute  molecules.  One  of 
the  corpuscles  appears  to  be  made  up  of  objects  like  the  pri- 
mitive discs  of  Dr.  Barry.  Compare  this  friable  exudation 
with  that,  fig.  2,  in  which  the  molecules  were  absent. 

Structure  of  Fibrinous  Exudations  in  Birds. 

It  would  be  interesting  to  examine  the  organic  germs  in 
the  fibrine  of  animals  with  blood-discs  differing  widely  from 
those  of  man  ;  and,  as  remarked  by  Dr.  Carpenter  in  his 
valuable  work  on  Human  Physiology,  p.  471,  observations  of 
this  kind  should  be  multiplied,  in  order  to  test  the  accuracy 
of  Dr.  Barry's  views  respecting  the  origin  of  the  tissues  and 
of  pus-globules  from  the  blood-discs. 

The  fibrine  obtained  by  washing  from  the  blood  of  birds 
contains  a  multitude  of  particles,  which  are  figured  in  the 
Philosophical  Magazine  for  August  1842,  like  the  nuclei  of 
the  blood- discs.  I  had  recently  an  opportunity  of  examining 
some  large  amber-coloured  and  nearly  transparent  clots  of 
fibrine  from  the  peritoneum  of  a  silver  pheasant. 

Fig.  6.  A,  corpuscles  in  the  exudation  from  the  bird  just 
mentioned.  The  connecting  fibrine  is  very  minutely  granu- 
lated, and  the  granules  are  so  arranged  in  some  parts  as  to 
present  a  very  faint  appearance  of  fibrils;  but  some  of  these 
seemed  to  be  quite  smooth,  and  they  are  somewhat  too  di- 
stinctly represented  in  the  engraving.  B,  filaments  about 
7(y<ji)(jtn  °f  an  mcn  'n  diameter,  which  as  they  are  always 


Minute  Anatomy  of  Animals. — No.  IV.  245 

most  abundant  when  putrefaction  is  just  commenced,  may  be 
infusory  productions.  They  occur  in  fibrine  from  the  healthy 
blood  of  man  and  other  animals,  as  well  as  in  fibrinous  ex- 
udations resulting  from  inflammation.  In  my  first  observa- 
tions, some  of  the  filaments  seemed  as  if  jointed,  but  this 
appearance  was  not  seen  afterwards.  Mr.  Dalrymple,  who 
examined  them  at  my  request,  remarked  that  they  appeared 
like  fine  tubes  containing  round  particles,  and  that  the  fila- 
ments were  similar  in  form  to  some  of  the  Vibrionia  of  Ehren- 
berg.     But  we  could  never  see  any  motion  in  the  filaments. 

As  I  propose  on  a  future  occasion  to  give  a  short  historical 
notice  of  the  observations  of  authors  on  the  structure  of  fibrine, 
I  shall  merely  allude  here  to  this  branch  of  the  subject.  The 
fibrinous  products  of  inflammation  have  commonly  been  de- 
scribed as  exudations  from  the  blood.  Thus  J.  Hunter,  who 
mentions  the  toughness  and  elasticity  of  coagulating  lymph, 
as  well  as  its  fibrous  and  laminated  appearance,  says  that  the 
swelling  in  inflammation  is  owing  to  the  extravasation  of  this 
lymph  and  some  serum.  Blumenbach's  views  are  of  the  same 
kind.  Dr.  Hodgkin  speaks  of  the  products  of  inflammation 
of  the  serous  membranes  as  effusions ;  and  Dr.  Alison  of 
"  inflammatory  effusions,  especially  that  of  pus."  Dr.  Davy 
particularly  describes  the  viscidity  of  coagulated  lymph  as  it 
passes  from  the  fluid  to  the  solid  state,  in  explanation  of  the 
formation  of  the  fibres  and  bands  of  the  common  adhesions 
of  the  lungs ;  this  property  of  fibrine  I  think  has  not  been 
noticed  by  any  other  author,  though  it  is  important,  and  may 
most  easily  be  demonstrated.  M.  Magendie*  has  given  an 
admirable  account,  from  microscopic  observation,  of  the  cel- 
lular, laminated,  and  filamentous  structure  of  fibrine,  which 
he  says  is  to  be  found  again  in  the  coagulum  that  obliterates 
blood-vessels,  as  well  as  in  the  formation  of  adhesions  and 
false  membranes ;  and  Dr.  Addison,  in  an  interesting  paper 
lately  published  (Prov.  Med.  and  Surg.  Journal,  August  20, 
1842),  concludes  from  his  observations,  that  "all  abnormal 
products  are  effusions  and  not  secretions." 

Mr.  Gerber  (Gen.  Anat.,  figs.  16-18)  has  delineated  what 
he  terms  the  first,  second,  and  complete  stages  of  fibrillation 
in  the  progress  of  organization  in  the  fibrine  composing  co- 
agulable  lymph;  but  he  does  not  say  how  much  his  drawings 
are  magnified,  though  in  some  of  them  a  very  low  power  must 
have  been  employed.  Others  are  sufficiently  enlarged  to  show 
the  cells  from  which  he  says  the  fibres  are  formed  ;  and  this 
is  precisely  the  point  in  which  my  observations  are  at  issue 

*  See  Mr.  Ancell's  Lectures  on  the  Blood,  Lancet  1839-40,  vol.  i. 
p.  459;  and  those  of  M.  Magendie  in  the  same  journal,  1838-39,  vol.  i. 
p.  255. 


246  M.  Dufrenoy's  Description  of  Greenovite. 

with  the  views  now  generally  entertained  concerning  the  ori- 
gin of  fibres. 

"  All  the  organic  tissues,"  says  Dr.  Schwann,  "  however 
different  they  may  be,  have  one  common  principle  of  develop- 
ment as  their  basis,  viz.  the  formation  of  cells ;  that  is  to  say, 
nature  never  unites  molecules  immediately  into  a  fibre,  a  tube, 
and  so  forth,  but  she  always  in  the  first  instance  forms  a  round 
cell,  or  changes,  when  it  is  requisite,  the  cells  into  various 
primary  tissues  as  they  present  themselves  in  the  adult  state." 
(Wagner's  Physiology  by  Willis,  p.  222.) 

How  is  the  origin  of  the  fibrils  which  I  have  depicted  in  so 
many  varieties  of  fibrine  to  be  reconciled  with  this  doctrine  ? 
And  what  is  the  proof  that  these  fibrils  may  not  be  the  pri- 
mordial fibres  of  animal  textures?  I  could  never  see  any 
satisfactory  evidence  that  the  fibrils  of  fibrine  are  changed 
cells;  and  indeed  in  many  cases  the  fibrils  are  formed  so 
quickly  after  coagulation,  that  their  production,  according  to 
the  views  of  the  eminent  physiologist  just  quoted,  would  hardly 
seem  possible-  Nor  have  I  been  able  to  see  that  these  fibrils 
arise  from  the  interior  of  the  blood-discs,  like  certain  fibres 
delineated  in  the  last  interesting  researches  of  Dr.  Barry. 

I  have  to  express  my  acknowledgements  to  Dr.  Dumbreck, 
Surgeon  72nd  Regiment,  and  to  Dr.  Boyd,  Resident  Physi- 
cian to  the  Marylebone  Infirmary,  for  their  kindness  in  afford- 
ing me  opportunities  of  examining  the  cases  just  mentioned; 
and  to  Mr.  Siddall  for  calling  my  attention  to  the  state  of  the 
blood  in  the  cases  noticed  in  the  last  Number  of  the  Philoso- 
phical Magazine. 


XLIII.    Description  of  Greenovite.    By  M.  Dufrenoy*.  * 

ly/T  DUFRENOY  states  that  this  mineral,  so  called  in 
•  honour  of  G.  B.  Greenough,  Esq.,  is  a  titaniate  of 
manganese,  and  except  crichtonite,  which  is  a  titaniate  of  iron, 
is  the  only  one  hitherto  described.  It  was  discovered  by  M. 
Bertrand-de-Lom  in  the  manganese  deposit  of  Saint  Marcel, 
in  Piedmont;  it  occurs  in  small  rose-coloured  veins  which 
run  irregularly  in  the  mass,  and  is  accompanied  by  quartz, 
epidoteand  manganesian  garnets.     It  was  supposed  originally 

Fig.  1 .  Fig.  2. 

o 


y         p 

b7 

f — r^~—^/r 

T 

/'  M 

.A 

h :/ 

/\ 

>^*' 

/K     '       •** 

/' t^-r— —     ^-\n>/ 

T^-—Lih--  V^m/ 

/^\ 

:X''7 

^*~-<^ 

*  From  the  dnnafes  drs  Mines,  vol.  xvii. 


M.  Dufrenoy's  Description  of  Greenovite.  247 

to  be  silicate  of  manganese,  and  is  placed  as  such  in  several 
collections  in  Paris. 

Greenovite  occurs  in  crystals  and  in  small  amorphous  cry- 
stalline masses ;  it  is  of  a  deep  rose  colour,  and  its  specific 
gravity  is  3*44.  Its  hardness  is  greater  than  that  of  fluor 
spar  or  phosphate  of  lime,  but  it  does  not  scratch  glass  ;  the 
crystals  are  splendent,  especially  the  faces  M  and  T ;  the  ter- 
minal faces  are  often  dull  and  tarnished. 

The  primary  form  of  the  crystal  is  represented  by  fig.  1, 
but  other  faces  have  been  observed,  as  shown  in  fig.  2. 

The  measured  and  partly  calculated  angles  areas  follows: — 


P  on  M  =  87° 

10' 

s 

on  T  =  83° 

56' 

P  ...  T  =  85 

50 

s 

...  P  =  153 

25 

M  ...  T  =  110 

35 

s' 

...  T  =  106 

30 

x   ...  M  =  119 

20 

s' 

...  x   —   146 

20 

x  ...   T  =  118 

10 

n 

...  T  =  110 

13 

x   ...  P  m   140 

6 

56" 

n 

...  P  =  155 

37 

s    ...  M  =  107 

50 

n' 

...  P  =  112 

V 

This  mineral  is  not  acted  upon  by  acids,  and  is  not  fusible 
perse  by  the  blow-pipe ;  microcosmic salt  denotes  the  presence 
of  titanium,  and  with  soda  it  shows  manganese. 

To  analyse  this  mineral,  M.  Cacarrie  fused  it  with  five 
times  its  weight  of  bisulphate  of  potash ;  the  residue  when 
cold  dissolved  slowly  in  water,  but  almost  entirely  ;  the  very 
small  quantity  which  remained  undissolved  contained  traces 
of  silica,  evidently  derived  from  quartz  mixed  with  the  green- 
ovite; the  rest  was  titanic  acid.  The  solution  was  treated 
with  hydrosulphuric  acid,  and  then  supersaturated  with  am- 
monia to  separate  the  lime.  The  residue,  composed  of  tita- 
nic acid  and  sulphuret  of  manganese,  was  digested  in  sul- 
phurous acid,  which  dissolved  the  sulphuret.  The  titanic 
acid  unacted  upon  was  collected,  and  there  was  also  obtained 
by  ebullition  a  trace  of  it  from  the  solution  of  manganese;  an 
accident  prevented  the  quantity  of  lime  from  being  determined, 
but  it  could  not  have  amounted  to  one  per  cent.  The  pro- 
portions of  the  other  constituents  were  ascertained  by  M.  Ca- 
carrie to  be 

Titanic  acid 745 

Oxide  of  manganese...  24*8 

Lime •  99'3 

[The  crystal  of  this  substance  appears,  from  the  author's 
statement,  to  be  a  doubly  oblique  prism,  but  from  the  sym- 
metrical "nature  of  the  faces,  and  the  near  approximation  of 
the  angles,  it  may  possibly  turn  out  to  be  an  oblique  rhombic 
prism.  We  have  not  however  seen  this  mineral. — Edit. 
Phil.  Mag.] 


[     248     j 

XLIV.  New  Definition  of  the  Voltaic  Circuity  with  Formula? 
for  ascertaining  its  Power  under  different  circumstances. 
By  Alfred  Smee,  F.R.S.* 

Theory  of  the  Voltaic  Circuit. 

IN  conducting  my  experiments  on  the  reduction  of  alloys, 
certain  phaenomena  and  peculiarities  were  noticed  that 
have  so  important  a  bearing  on  the  theory,  or  rather  the 
rationale  of  the  voltaic  current,  that  it  becomes  my  duty 
at  once  to  draw  up  the  curtain  and  expose  the  conclusions 
to  which  they  lead,  as  a  knowledge  of  them  will  give  to  the 
operator  great  advantages,  and  enable  him,  by  rightly  un- 
derstanding the  force  with  which  he  is  working,  to  conduct 
his  various  processes  to  the  best  possible  advantage. 

In  these  experiments  I  noticed  that  in  various  mixed  solu- 
tions the  quantity  of  voltaic  force  passing  was  not  at  all  de- 
pendent on  the  nature  of  the  negative  element,  but  upon  the 
ease  with  which  the  hydrogen  was  removed  from  it.  Thus  in 
a  solution  of  sulphate  of  zinc  very  slightly  acidulated  the  hy- 
drogen could  not  be  evolved  from  smooth  copper,  but  would 
rather  reduce  the  sulphate  of  zinc  when  connected  with  a 
small  battery.  The  substitution  of  smooth  platinum  in  no 
way  added  to  the  power,  but  the  employment  of  platinized 
platinum  caused  an  abundant  evolution  of  gas,  even  to  the  re- 
moval of  the  zinc  already  reduced  on  the  smooth  platinum. 
Any  metal  having  but  little  affinity  for  hydrogen  caused  a  si- 
milar result;  thus,  iron  caused  gas  to  be  evolved  and  increased 
the  force  passing,  when  smooth  platinum  would  not  have  the 
effect,  and  even  zinc  itself  caused  a  little  gas  to  be  evolved, 
because  the  adhesion  of  the  gas  to  it  is  slighter  than  the  ad- 
hesion to  smooth  platinum. 

In  the  same  way  I  observed  that  nitric  acid  allowed  far 
more  electricity  to  pass  than  sulphate  of  copper;  and  that 
again,  than  dilute  sulphuric  acid,  simply  from  the  facility  with 
which  hydrogen  reduces  these  substances  being  greater  than 
the  facility  of  its  evolution.  I  moreover  noticed  in  other 
cases  that  the  hydrogen  would  rather  be  evolved  than  re- 
duce a  metallic  salt, — as  sulphate  of  zinc ; — and  in  every  case 
that  the  facility  of  its  removal  affected  the  amount  of  power 
passing,  quite  independently  of  the  nature  of  the  negative 
plate. 

Now  these  facts  appeared  to  me  a  positive  proof  of  there 
being  no  such  thing  as  a  negative  plate  contributing  to  the 

*  Reprinted,  with  additions  and  corrections  by  the  author,  from  a  pam- 
phlet extracted,  for  private  circulation,  from  his  "Elements  of  Electro-me- 
tallurgy." 


Mr.  Smee's  New  Definition  of  the  Voltaic  Circuit.     249 

production  of  power,  and  that  this  latter  is  of  no  value,  further 
than  as  a  means  for  the  removal  of  the  second  element  of  the 
intervening  compound  fluid.  On  the  other  hand,  the  mul- 
titude of  experiments  by  Faraday  all  show  that  the  chemical 
action  between  one  element  of  a  compound  fluid  and  some 
conducting  body  appears  to  be  the  source  of  the  power, 
or  rather  that  the  power  is  always  directly  proportionate 
to  this  chemical  action.  Putting  these  two  series  of  facts 
together,  an  idea  presented  itself  to  my  mind  explanatory 
of  the  nature  of  the  voltaic  force,  for  if  the  force  from  the 
experiments  of  Faraday  is  proved  to  depend  on  chemical 
action,  and  the  negative  pole  from  my  own  experiments  is 
proved  to  be  useless,  except  as  affording  the  means  for  the  re- 
moval of  the  second  element  of  the  compound  fluid,  then  it 
follows  as  a  natural  consequence,  that  if  the  chemical  affinity 
of  any  substance  for  one  element  of  a  compound  fluid  is 
greater  than  the  resistance  offered  to  the  evolution  of  the 
second,  force  is  produced.  Now  it  immediately  occurred  to 
me  that  some  metals  might  be  made  to  reduce  from  a  solution 
of  one  of  their  own  salts,  metal  of  the  same  description,  by 
placing  the  metal  partly  in  a  solution  for  one  element  of  which 
it  has  great  affinity  and  in  which  it  is  easily  dissolved,  and 
partly  in  a  solution  of  one  of  its  salts.  This  was  actually 
found  to  take  place  in  various  cases,  by  following  the  facts 
that  were  made  out  respecting  the  ease  with  which  hydrogen 
reduces  various  salts. 

■  Zinc  reduces  zinc  by  taking  a  piece  of  the  metal  and  doubling 
it,  one  half  is  then  to  be  amalgamated  and  placed  in  dilute 
muriatic  acid,  and  the  unamalgamated  into  a  strong  solu- 
tion of  chloride  of  zinc,  made  as  neutral  as  possible,  when 
the  affinity  of  the  zinc  for  the  oxygen  and  the  quick  removal 
of  the  oxide  by  miiriatic  acid  is  sufficiently  great  to  cause 
zinc  to  be  reduced  at  the  other  end  of  the  same  piece  of  metal. 
The  use  of  platinum,  palladium,  silver,  copper,  or  any  other 
metal  appears  not  to  increase  the  action  in  the  least,  which 
experiment  shows  most  powerfully  the  utter  fallacy  of  the  con- 
tact theory,  or  in  other  words,  that  the  voltaic  force  is  in  any 
degree  dependent  on  the  opposition  of  one  substance  to  another. 
In  this  experiment,  according  to  the  advocates  of  this  now 
untenable  doctrine,  the  force  should  have  set  from  the  amal- 
gamated zinc  to  the  mercury,  the  two  metals,  according  to 
those  electricians,  having  from  simply  looking  at  each  other 
the  property  of  evolving  power, — but  we  find  that  the  che- 
mical affinity  determined  the  course  of  the  current. 

Copper  may  by  very  simple  means  be  made  to  reduce  cop- 
per with  truly  great  rapidity ;  for  if  a  test  tube  be  half  filled 
with  sulphate  of  copper,  and  then  muriatic  acid  be  poured 


250       Mr.  Smee's  New  Dejinition  of  the  Voltaic  Circuit, 

gently  at  the  top,  so  that  the  two  fluids  do  not  mix  to  any 
great  extent,  and  a  copper  wire  be  then  placed  throughout 
the  whole  length  of  the  tube,  it  will  speedily  show  signs  of 
action.  The  copper  in  the  acid  will  rapidly  dissolve,  whilst 
copper  will  be  as  freely  deposited  at  the  lower  part  of  the 
vessel.  Now  copper  will  undergo  no  action  alone,  either  in 
muriatic  acid  or  sulphate  of  copper.  This  experiment  may 
be  varied  by  the  use  of  different  acids  or  even  some  salts  at 
the  upper  part  of  the  vessel,  for  although  muriatic  acid  shows 
this  experiment  most  strongly,  dilute  sulphuric  acid  or  mu- 
riate of  ammonia  will  produce  the  same  result. 

Silver  reduces  silver  by  placing  one  end  of  a  silver  wire  in 
a  porous  tube  containing  nitrate  of  silver,  the  other  in  dilute 
sulphuric  acid,  though  the  metal  placed  in  either  separately 
is  not  affected. 

Lead  reduces  lead  by  immersing  one  end  of  a  piece  of  lead 
in  a  solution  of  the  tris-nitrate  of  lead,  the  other  in  dilute 
nitric  acid. 

Tin  reduces  tin  by  placing  one  portion  of  a  piece  of  metal 
in  muriate  of  tin,  the  other  in  muriatic  acid. 

Gold  even  reduces  gold  by  immersing  one  end  of  a  gold 
wire  in  the  chloride,  the  other  in  dilute  muriatic  acid,  the  two 
solutions  being  separated  as  in  all  the  former  cases  by  a  po- 
rous diaphragm. 

There  is  a  beautiful  experiment  detailed  by  Mr.  Grove, 
which  is  analogous  to  those  last  described,  though  he  attri- 
buted the  results  to  a  different  cause*.  His  experiment  is  to 
place  two  pieces  of  gold  wire  in  muriatic  and  nitric  acid,  sepa- 
rated by  a  porous  diaphragm,  when  no  action  will  take  place 
on  either,  but  on  being  connected,  that  in  muriatic  acid  will 
rapidly  be  dissolved,  and  the  nitric  acid  will  at  the  same  time 
be  decomposed  by  the  hydrogen  transferred  to  the  other  part 
of  the  wire. 

From  the  various  experiments  which  I  have  examined, 
added  to  the  extensive  researches  of  Faraday  on  the  chemical 
portion  of  the  voltaic  pile,  the  voltaic  phaenomena  may  be  de- 
fined to  be  certain  effects  produced  by  the  chemical  action  of 
a  body  on  one  element  of  a  compound,  and  manifested  be- 
tween this  point  of  action  and  the  evolution  of  the  second 
element.  The  voltaic  phaenomena  might  in  other  words  also 
be  defined  to  be  peculiar  properties  evinced  between  the  che- 
mical action  of  a  body  on  one  element  of  a  compound,  and 
the  evolution  of  the  second  element,  the  point  of  abstraction 
and  subsequent  combination  of  the  first  element  being  called 
the  positive  pole  j  the  point  of  evolution  or  removal  of  the 
second  element  of  the  compound  body,  the  negative  pole. 
[*  See  Phi!.  Mag.,  Third  Series,  vol.  xiv.  p.  388.— Edit.] 


with  Formula:  for  ascertaining  its  power.  25 1 

Hence  it  might  be  called  circular  chemical  action,  because 
the  phenomenon  always  evinces  itself  as  a  circle. 

These  definitions  suit  equally  every  possible  case,  and  there 
is  but  one  point  included  in  those  definitions  which  is  uncer- 
tain, though  as  they  now  stand,  whichever  way  that  doubtful 
case  be  taken,  they  equally  apply.  The  difficulty,  and  the 
only  one,  that  I  know  concerning  the  production  of  the  voltaic 
force,  is  an  uncertainty  whether  the  force  is  produced  by  the 
analysis  of  the  compound  body,  or  the  synthesis  of  the  newly- 
formed  salt.  This  is  a  point  concerning  which,  perhaps,  we 
shall  ever  be  ignorant,  yet  analogy  would  rather  lead  us  to 
suppose  that  the  combination  rather  than  the  analysis  is  the 
source  of  the  voltaic  force.  These  definitions  show  why  we 
cannot  obtain  the  force  from  the  union  of  two  elements ;  in- 
deed, we  can  never  hope  to  obtain  voltaic  power  from  ordinary 
combustion;  for  though  the  energy  of  the  combination  of  oxy- 
gen with  carbon  is  immense,  there  is  no  second  element,  and 
therefore  no  intermediate  point  at  which  the  effects  can  be 
manifested.  For  the  same  reason  no  force  can  be  obtained 
from  the  union  of  liquid  sulphur  or  bromine  with  metals. 

The  intensity  of  chemical  action  being  always  proportionate 
to  the  voltaic  power,  and  being  the  only  source  of  power  in 
the  pile,  it  follows  that  (I)  the  intensity  or  the  power  the  vol- 
taic fluid  possesses  of  overcoming  obstacles  is  equal  to  (F), 
the  affinity  which  regulates  the  chemical  action.  But  as  we 
find  that  this  power  is  lessened  under  different  circumstances, 
I  =  F  —  O ;  O  standing  for  the  whole  of  the  obstacles  af- 
forded to  its  passage. 

Let  us  take  at  once  a  circle  and  examine  its  properties. 
We  find  that  the  intensity  of  the  action  (I)  is  equal  to  the 
affinity  (F)  of  the  body  used  to 
separate  one  element  of  the  com-  Fig.  1 . 

pound  fluid  (in  the  galvanic  bat- 
tery this  is  produced  by  the  zinc 
and  oxygen)  lessened  by  the  me- 
chanical resistances  afforded  by 
the  removal  of  the  newly-formed 
compound  (a)  by  the  obstruction 
offered  to  the  passage  of  the 
force  by  the  compound  solution  (r),by  the  imperfection  of  the 
conducting  power  of  the  solid  parts  of  the  circuit  (c),  and 
lastly,  by  the  obstacle  which  is  afforded  to  the  removal  of  the 
second  element  of  the  compound  fluid  (e) ;  thus  we  have  al- 
gebraically I  =  F  —  a  +  c  +  r  +  e.  This  circle  is  supposed  to 
consist  of  but  a  single  atom  of  fluid,  exposed  at  one  time 
to  the  action  of  the  body  combining  with  one  of  its  elements, 


252      Mr.  Smee's  New  Definition  of  the  Voltaic  Circuit, 

and  all  the  resistances  are  supposed  to  be  constant.  In  some 
cases  we  might  be  desirous  of  ascertaining  the  values  of  the 
other  parts  of  the  circle ;  thus  if  we  desired  to  find  the  affinity 
(F)  F  =  I  +  a  +  c  +  r  +  e, — the  conducting  power  of  the  con- 
necting part  of  the  arrangement  (c)c=  F  —  l  +  a  +  r  +  e.  The 
removal  of  the  newly  found  compound  (a)  a=F  —  L+c  +  r  +  e, 
the  resistance  offered  by  the  compound  fluid  (r)  r  =  F 
—  l  +  a+c  +  e,  the  resistance  to  the  removal  of  the  second 
element  of  the  compound  e  =  F— I  +  a  +  c  +  r. 

Sometimes  this  circle  is  exceedingly  small,  the  (r)  consist- 
ing of  but  one  atom  of  the  compound,  and  (c)  but  of  a 
single  atom  of  the  body  combining  with  one  element.  This 
might  be  properly  called  an  atomic  circle,  a  good  specimen  of 
which  has  heretofore  been  called  local  action. 

We  must  now  consider  the  different  parts  of  the  circle  in 
detail ;  and  now  a  question  naturally  arises  whether  the  inter- 
vening compound  may  consist  of  any  number  of  elements,  or 
whether  it  is  essential  that  the  compound  should  be  made  up  of 
only  two  elements.  From  a  consideration  of  the  voluminous 
experiments  of  our  great  authority  Faraday,  it  would  appear 
probable  that  the  second  hypothesis  is  correct,  although  it 
is  just  possible  that  if  the  body  consists  of  more  than  two  ele- 
ments, that  the  impediment  to  the  evolution  of  the  other  ele- 
ments (e)  or  the  resistance  of  the  fluid  part  (r)  become  so  enor- 
mously increased  as  to  stop  any  (F)  or  series  of  (F)  that  we 
have  ever  applied.  Another  question  also  arises,  as  to  whether 
compound  must  necessarily  be  a  fluid  which  requires  the  same 
consideration  as  the  first  question. 

(F)  the  chemical  affinity  of  a  body  for  one  element  of  a  com- 
pound is  immensely  strong  where  zinc  is  employed,  the  at- 
traction of  that  metal  for  oxygen  being  most  powerful ;  but 
if  we  substitute  iron,  tin,  lead,  copper,  or  gold,  for  the  zinc, 
the  attraction  being  feeble,  the  value  of  (F)  would  be  reduced 
in  various  proportions,  in  some  cases  almost  to  zero. 

(a)  the  removal  of  the  newly-formed  compound  affords  but 
little  resistance  when  the  new  salt  is  soluble  in  the  fluid  and  a 
sufficiency  is  supplied  for  that  purpose.  In  batteries  gene- 
rally the  removal  of  sulphate  of  zinc  affords  but  little  obstacle, 
being  quickly  dissolved  by  water  ;  (a)  in  some  cases  is  the 
removal  of  the  first  element  of  the  compound  by  evolution, 
thus  in  the  voltameter  oxygen  is  evolved.  In  these  cases  (a)  is 
very  large,  and  offers  great  obstacles  to  the  passage  of  the  cur- 
rent. The  removal  of  the  first  element  is  sometimes  accom- 
plished by  decomposition ;  thus  oxygen  may  be  removed  by 
hydriodic  acid,  by  the  decomposition  of  which  body  (a)  is  di- 


with  Formula  for  ascertaining  its  power,  253 

minished  and  the  current  of  one  battery  will  pass  through  it. 
The  observations  made  with  regard  to  the  reduction  of  alloys 
in  the  case  of  e  apply  equally  to  (a),  for  the  first  element  will  al- 
ways be  removed  in  the  manner  which  affords  least  resistance. 

(r)  varies  very  much  from  the  extent  of  the  interposed  fluid, 
and  its  conducting  power  being  very  different  in  each  case.  It 
varies  much  in  different  batteries.  Sometimes  r  is  a  very  com- 
plex quantity,  as  when  two  or  more  solutions  of  different  con- 
ducting power  are  used  between  the  combination  of  one  ele- 
ment of  a  compound  and  the  evolution  of  the  second.  In 
Daniell's  battery,  for  instance,  it  is  made  up  of  three  parts, 
not  only  the  resistance  offered  by  dilute  sulphuric  acid  and 
solution  of  sulphate  of  copper,  but  also  a  resistance  offered 
by  the  interposed  diaphragm.  It  might  be  made  up  of  a  far 
greater  number  of  parts,  for  different  parts  may  be  of  differ- 
ent temperatures,  which  alone  (if  the  temperature  interferes 
with  the  conducting  power)  would  cause  r  to  be  complex. 
(r)  becomes  enormously  increased  when  the  force  is  compelled 
to  travel  round  a  corner. 

(c)  the  resistance  of  the  connecting  part  of  the  arrange- 
ment is  generally  in  batteries  very  slight,  because  we  select 
metals  which  conduct  pretty  freely  ;  (c)  may  be  very  complex 
by  being  made  of  a  variety  of  conducting  substances;  thus,  if 
the  connexions  are  made  of  wires  of  different  kinds  of  metal, 
a  different  resistance  is  offered  by  each,  (c)  in  every  battery, 
is  generally  made  up  of  three  parts,  the  conducting  power  of 
the  positive  and  negative  plates,  and  the  intervening  connect- 
ing wires. 

(e)  the  resistance  to  the  removal  of  the  second  element  *,  is 
generally  very  great,  affording  a  considerable  obstacle  in  all 
cases,  but  the  differences  in  this  respect  are  very  remarkable. 
Ordinarily  (e)  is  a  simple  quantity,  but  becomes  complex  when 
the  hydrogen  is  removed  in  a  variety  of  ways  at  the  same  mo- 
ment. It  becomes  a  curious  question  to  ascertain  whether 
(e)  might  ever  be  made  a  plus  quantity.  If  the  force  pro- 
ceeds from  analyis,  then  the  use  of  any  body  having  great 
affinity  for  the  second  element  might  cause  the  current  to  be 
increased.  If  from  synthesis,  and  this  is  most  probable,  if 
not  absolutely  certain,  (e)  can  never  be  a  plus  quantity,  but 
always  a  minus.  In  the  removal  of  the  second  element  by 
decomposition  of  another  compound  body,  it  is  by  no  means 
uncommon  for  a  voltaic  circuit  to  be  formed.     In  Grove's 

*  The  term  second  here  may  require  explanation,  for  it  is  only  used  in 
contradistinction  to  the  term  first,  which  is  applied  to  that  element  which 
by  combination  forms  F.  Either  element  of  a  compound  may  be  first  or 
second,  according  as  it  may  happen  to  assist  in  the  propagation  of  the  force. 


254     Mr  4  Smee's  Nexv  Definition  of  the  Voltaic  Circuit, 

battery  the  hydrogen  acts  upon  nitric  acid,  forming  water, 
and  setting  deutoxide  of  nitrogen,  &c.  free ;  but  in  this  case 
the  intermediate  part  between  the  combination  of  the  first 
element  and  the  removal  of  the  second,  is  only  the  atom  of 
hydrogen ;  it  therefore  follows  that  this  action  must  be  re- 
garded as  nothing  but  a  series  of  little  local  batteries,  or  atomic 
circles,  having  nothing  to  do  with  the  great  battery  which  we 
make  available  for  our  purposes. 

It  is  absolutely  essential,  according  to  our  definition  of  the 
voltaic  force,  that  to  be  enabled  to  apply  this  principle  for  any 
purpose,  however  small  a  quantity  of  the  force  may  be  re- 
quired, that  either  (c)  or  (r)  should  possess  a  capability  of 
being  so  far  prolonged  as  to  enable  us,  with  the  imperfect 
powers  that  nature  has  furnished  us,  to  handle  or  deal  with 
these  intervening  portions  of  the  circuit. 

In  the  principal  batteries  now  in  use,  their  relative  powers 
and  attributes  may  be  fully  understood  by  considering  each  of 
the  above  properties  in  their  construction. 

F.         a.  c.             r.                 e. 

Grove large  small  small  medium  little. 

Daniell  large  small  small  most  much. 

Smee  large  small  small  small  much. 

Smooth  platinum  large  small  small  small  enormous. 

Thus  the  four  batteries  may  be  considered  equal  in  the 
properties  of  the  F,  a,  c,  the  differences  being  only  in  (r)  and 
(e).  In  Grove's  the  (e)  is  so  small  as  not  only  to  compensate 
a  slight  increase  in  the  (r)  over  mine,  as  usually  constructed, 
but  to  give  a  great  advantage  to  his  form  of  battery.  In 
DanielFs  the  (e)  is  perhaps  rather  smaller  than  in  mine,  but 
that  is  more  than  counterbalanced  by  (r)  being  larger  in 
Daniell's  than  in  mine.  The  effect  of  these  properties  are, 
that  F  in  Grove's  is  diminished  but  little,  F  in  mine  more,  in 
Daniell's  more  still;  and  in  the  smooth  platinum  battery  by 
far  the  most.  Thus  is  explained  the  decomposition  of  dilute 
sulphuric  acid  between  platinum  plates,  by  one  cell  of  Grove's 
battery,  and  the  same  result  not  being  obtained  by  the  others. 
This  equation  is  not  only  valuable  for  batteries,  but  applies  to 
every  single  case  where  any  substance  acts  upon  a  compound 
fluid  in  such  a  way  as  first  to  decompose  it,  then  to  combine 
with  one  of  its  elements,  and  set  free  in  some  way  the  other. 
Thus,  if  potassium  be  cast  into  dilute  muriatic  acid,  (F)  is  im- 
mensely large,  potassium  having  a  violent  affinity  for  oxy- 
gen; («)  is  exceedingly  small,  potash  being  readily  soluble  in 
water;  (r)  is  almost  nothing,  only  one  atom  of  fluid  being 
traversed  by  the  force;  (c)  is  practically  nothing  from  the 


with  Formula:  for  ascertaining  its  poxver.  255 

same  cause;  (e)  is  very  small.  The  result  of  such  a  state  of 
things  necessarily  causes  a  vast  intensity  of  action,  and  an  ex- 
plosion is  the  result. 

Good  specimens  of  contrasts  in  the  magnitude  in  the  se- 
veral parts  of  the  circuit  are  to  be  seen  in  the  relative  power 
of  (F),  as  obtained  by  zinc  and  silver;  in  the  relative  resist- 
ance of  (a)  in  the  solubility  of  sulphate  of  lead  and  sulphate 
of  zinc ;  in  the  resistance  of  (r)  in  the  conducting  power  of 
pure  water  and  muriatic  acid;  of  the  resistance  of  (c)  in  a 
leaden  wire  a  hundred  miles  long,  and  a  short  silver  one;  in 
the  resistance  of  (e)  in  the  evolution  of  hydrogen  from  smooth 
platinum,  and  its  removal  by  nitric  acid. 

The  relative  degrees  of  action  evinced  by  zinc,  tin,  iron, 
and  lead  upon  sulphate  of  copper  are  easily  explained;  (F) 
differs  from  being  larger,  (a)  in  being  smaller  when  zinc  is 
employed,  whilst  (c),  (r),  (e)  in  each  case  remain  nearly  the 
same ;  (a)  indeed  is  so  large  when  lead  is  employed  as  soon 
to  put  a  stop  to  the  action. 

How  intelligible  is  the  want  of  action  of  dilute  sulphuric  acid 
on  amalgamated  zinc,  if  examined  by  our  equation  for  (c) !  the 
adhesion  of  the  second  element,  hydrogen,  being  increased 
enormously,  counterbalances  (F),  the  affinity  of  zinc  for  the 
first  element,  or  oxygen,  and  no  action  takes  place.  Amalga- 
mated zinc  is  rapidly  dissolved  if  placed  in  a  solution  of  salts 
of  copper  or  silver,  for  (e)  in  that  case  is  depressed,  the  hy- 
drogen rapidly  reducing  the  copper.  Nitric  acid  in  the  same 
way  does  not  respect  the  amalgamation  of  the  zinc,  for  (e)  in 
that  case  is  also  diminished  by  the  removal  of  hydrogen  from 
the  decomposition  of  the  acid.  As  the  adhesion  of  hydrogen 
to  plumbago  is  very  great,  it  occurred  to  me  that  the  simple 
application  of  black-lead  to  zinc  would,  by  preventing  the 
evolution  of  hydrogen,  increase  (e),  and  therefore  stop  the 
local  action ;  but  although  the  experiment  fully  succeeded, 
the  plumbago  so  quickly  came  off,  that  I  have  not  at  present 
made  any  practical  application  of  the  experiment. 

The  above  cases,  with  all  their  analogies,  are  not  the  only 
ones  to  which  the  equation  applies,  for  it  will  account  per- 
fectly for  the  action  of  bodies  on  each  other. 

In  cases  of  single  elective  affinity,  as  the  action  of  sulphuric 
acid  on  nitrate  of  barytes,  a  compound  is  decomposed,  one 
element  enters  into  another  combination,  the  other  is  set  free ; 
a  voltaic  circuit  is  therefore  produced,  the  parts  of  which  are 
thus  made:  (c)  Sulphuric  acidl(F) 

o)/Bar>'tes .       j  (a) 

v  '  \Nitric  acid     (e) 
In  cases  of  double  elective  affinity,  as  the  action  of  sulphate 


256       M  r.  Smee's  New  Definition  of  the  Voltaic  Circuit, 

of  ammonia  on  nitrate  of  barytes,  a  similar  circuit  is  formed 
thus:—  ^) 

(F) /"Sulphuric  acid     Ammonia  ~\,  .* 
(a)   |_Barytes  Nitric  acidj  v' 

In  both  these  cases,  however,  we  have  not  the  means  of  in- 
creasing the  (r)  and  (c)  to  a  tangible  size  (at  least  I  have  never 
been  able  to  do  it),  and  at  present  these  actions  have  been 
restricted  to  the  formation  of  atomic  circles. 

There  are  some  cases  where  we  can  extend  the  intermediate 
parts  (c)  and  (r),  and  then  our  definition  of  the  voltaic  force 
with  the  formula  arising  from  it  enables  us  to  form  most  ex- 
traordinary voltaic  circles,  which  indeed  we  never  could  have 
formed  before,  unless  we  happened  to  light  upon  them  by 
chance :  thus  proto-sulphate  of  iron,  placed  on  one  side  of  a 
diaphragm,  and  nitrate  of  silver  on  the  other,  will  give  a  cur- 
rent when  connected  with  a  platinum  wire,  and  a  beautiful 
deposit  of  silver  will  be  reduced  on  the  platinum  wire,  on  the 
nitrate  of  silver  side  of  the  circuit. 

In  the  same  manner  circuits  may  be  formed  of  proto-sul- 
phate of  iron  and  chloride  of  gold — of  proto-nitrate  of  mer- 
cury and  chloride  of  gold — of  oxalic  acid  and  chloride  of 
gold,  &c.  In  all  of  which  cases  the  metal  is  freely  reduced 
on  that  part  of  the  platinum  wire  inserted  in  the  metallic  salt. 
The  reason  why  a  galvanic  circuit  is  formed  in  these  cases  is 
sufficiently  obvious ;  water  is  the  electrolyte  or  compound 
decomposed,  proto-sulphate  of  iron  is  the  substance  combining 
with  one  element,  and  the  metallic  salt  affords  a  means  for  the 
removal  of  the  second  element  or  hydrogen,  and  as  we  have 
the  power  of  extending  the  compound  (r)  and  connecting 
parts  (c),  not  only  an  atomic  circuit,  but  a  working  battery 
may  be  made.  At  the  diaphragm  or  the  point  of  juncture  of 
the  two  liquids,  indeed,  an  atomic  or  local  battery  is  formed 
independently  of  the  general  or  working  battery.  A  second 
local  battery  is  formed  at  the  point  of  decomposition  of  the 
metallic  salt  by  the  hydrogen.  The  following  are  the  parts 
of  the  circuit  in  the  above  cases. 

~ _) 

(F)f  Proto-sulphate  of  iron       Platinum  wire 
f(a)  \_Oxygen  Hydrogen  {e)f 

*  The  (e)  in  this  case  does  not  form  a  secondary  voltaic  circle,  but  is 
the  union  of  two  primitive  elements. 

f  (a)  is  the  removal  of  the  per-sulphate  of  iron  by  solution  ;  (e)  is  the 
removal  of  the  hydrogen  by  the  decomposition  of  the  metallic  salt. 


with  Formula  for  ascertaining  its  power.  257 

It  would  be  extremely  interesting  to  find  every  case  of  de- 
composition of  a  compound  fluid  obedient  to  the  equation,  and 
indeed  there  is  every  appearance  of  that  being  the  fact. 

The  impossibility  of  giving  a  negative  tendency  to  a  metal 
when  hydrogen  is  removed  from  its  surface  is  also  perfectly 
accounted  for  by  our  equation ;  for  hydrogen,  as  has  been  al- 
ready shown,  protects  the  metal ;  so  when  a  facility  is  offered 
for  its  removal,  not  only  is  the  direct  protection  removed,  but 
by  diminishing  the  value  of  [e),  (F)  the  natural  affinity  of  the 
metal  for  one  element  of  the  fluid,  having  but  little  resistance 
opposed  to  it,  begins  to  act,  and  the  metal  is  therefore  dissolved. 

The  superior  action  of  a  rough  metal  in  contrast  with  a 
smooth  one,  is  explainable  on  the  equation  most  satisfactorily, 
for  in  the  first  case  the  affinity  (F)  is  but  feebly  opposed  by  the 
resistance  to  the  evolution  of  the  hydrogen  (e)t  whilst  in  the 
latter  case  (F)  is  so  strongly  opposed  by  (e)  that  no  action  can 
take  place.  Zinc  shavings,  which  always  have  one  side  bright 
and  the  other  rough,  show  this  phenomenon  clearly.  Polished 
zinc  or  iron  also  show  this  effect  in  a  striking  manner. 

Hitherto  we  have  considered  (F,  a,  c,r,e)  in  every  case  to 
be  constant,  but  in  many  instances  they  are  subjected  to  con- 
tinual variation.  I  do  not,  indeed,  happen  to  recollect  an  in- 
stance of  (F)  varying  to  any  amount,  but  (a)  varies  frequently ; 
in  the  gradual  saturation  of  a  fluid  it  progressively  increases, 
so  much  so,  as  at  last  to  equal  (F).  This  accounts  for  zinc 
ceasing  to  be  dissolved  on  the  saturation  of  the  fluid  by  sul- 
phate of  zinc,  although  still  intensely  acid,  (c)  generally  re- 
mains constant,  (r)  is  very  unsteady,  for  as  in  all  voltaic  ar- 
rangements the  fluid  is  always  undergoing  change,  it  is  there- 
fore sure  to  be  altered  in  its  conducting  power,  (e)  is  sub- 
ject to  great  variations  from  alteration  of  the  liquid  and  other 
causes. 

In  every  case  of  a  single  battery  we  have  seen  that  the  in- 
tensity is  equal  to  chemical  affinity,  minus  the  resistances  to 
that  affinity.  In  a  compound  battery  the  expression  is  equally 
simple,  for  the  intensity  is  equal  to  the  sum  of  the  affinities, 
minus  the  sum  of  the  resistances.     In  a  series  of  batteries  all 


of  the  same  nature,  V  =  F-a+c+r  +  fx».  Sometimes  (») 
is  very  complex.  For  example,  if  a  compound  battery  be 
made  up  of  a  Grove's,  a  DanielPs,  and  my  own,  the  values  of 
(I)  must  be  considered  separately,  and  their  sum  taken. 

The  diagram  exhibits  well  the  arrangement  and  properties 
of  the  compound  battery. 

A  good  example  of  the  effect  of  (n)  is  seen  in  the  water 
battery,  where  (I)  is  exceedingly  small  from  the  resistances 

Phil.  Mag.  S.  3.  Vol.  21.  No.  1 38.  Oct.  1842.        S 


258     Mr.  Smee's  New  Definition  of  the  Voltaic  Circuit, 

of  (a)  and  (r)  being  large,  but  becomes  amplified  to  such  a 

Fig.  2. 


degree  by  («)  as  to  possess  prodigious  force;  indeed  as  it 
possesses  a  capability  of  being  amplified  infinitely  by  an  infinite 
series  completely  insulated,  a  battery  might  be  constructed 
powerful  enough  for  the  force  to  pass  from  one  electrode, 
placed  in  the  Thames  at  London  Bridge,  and  the  other  in  some 
river  in  Australia,  though  the  resistances  of  (r)  and  (c)  in  this 
case,  from  their  extreme  length,  would  be  very  great.  In 
every  water  battery,  as  (a)  instead  of  being  constant  gradually 
increases,  the  power  gradually  declines  at  length  to  nothing. 
The  curious  and  wonderfully-multiplying  powers  of  (w), 
whereby  the  intensity  can  be  increased,  precludes  our  saying 
that  the  galvanic  power  is  unable  to  effect  any  particular  ob- 
ject; for,  after  all,  it  might  turn  out  that  (n)  was  not  magni- 
fied sufficiently  to  attain  that  end. 

If  we  desire  to  find  the  number  of  batteries  in  any  arrange- 
ment, it  could  be  easily  ascertained  by  the  following  equation  : 

n  = =. 

F  —  a  +  c  +  r  +  e 
When  we  are  turning  our  power  to  some  application  it  is 
very  convenient  to  consider  the  purpose  for  which  it  is  applied 
as  a  resistance,  and  call  it  R.  If  we  have  a  series  of  them 
alike  it  would  be  R  x  m,  m  standing  for  the  number  composing 
the  series.  If,  however,  the  series  is  not  alike,  it  would  be 
R  +  R'  -f  R".  The  intensity  of  the  current  after  having  passed 
this  resistance  would  be  also  equal  to  the  sum  of  the  intensities, 

minus  the  sum  of  the  resistances,  l"  =  F— a+c-i-r  +  exn  —  R;«. 
The  R  is  frequently  very  complex,  as  in  the  reduction  of  me- 
tals in  a  decomposition  trough,  where  it  is  made  up  of  as  many 
parts  as  a  voltaic  battery. 

Having  amply  discussed  the  power  of  the  force  to  overcome 
obstacles,  we  are  led  to  determine  the  time  in  which  any  given 
number  of  equivalents  of  voltaic  power  can  be  obtained. 
Hitherto  we  have  considered  the  circuit  to  be  made  up  of  a  sin- 
gle atom  of  the  body  combining  with  one  element  of  the  com- 
pound, and  if  the  affinity  exceeds  but  ever  such  a  trifle  its 


with  Formula:  for  ascertaining  its  power.  259 

obstacles,  then  in  time  any  amount  of  work  would  be  per- 
formed provided  the  current  remained  constant.  A  current 
can  easily  be  conceived  so  feeble  as  to  take  millions  of  years 
to  reduce  a  pound  of  copper.  If  the  entire  circuit  of  single 
atoms  be  increased  at  every  part,  in  fact  if  the  mathematical 
voltaic  circle  be  increased  to  the  size  of  a  tunnel,  then  (W),  the 
amount  of  work  performed  in  a  given  time,  would  be  equal  to  the 
intensity  of  the  battery,  minus  the  resistance  of  our  working 
apparatus,  multiplied  by  the  number  of  parts  of  the  tunnel 

(A)  thus:  W=T^nr!.xA. 

This  equation,  however,  gives  us  the  total  amount  of  che- 
mical actions  in  the  whole  series  of  batteries  and  decomposi- 
tion troughs,  or,  in  other  words,  the  sum  of  the  actions  evinced 
in  each;  we  generally,  however,  are  desirous  of  estimating 
the  amount  done  in  one  particular  cell,  in  which  case  we  di- 
vide our  equation  by  the  number  of  cells  and  troughs  (n)  thus : 

n 
Sometimes  this  equation  is  rendered  extremely  complex  by 
an  increase  of  the  circuit  at  one  side  but  not  at  another ;  in 
fact,  the  tunnel  is  cut  away  on  one  side,  and  this  is  a  case  that 
is  perpetually  occurring  in  practice.  In  this  case  it  is  not 
impossible  but  that  the  force  is  only  derived  from  those  parts 
of  the  circuit  which  are  complete :  in  that  case  the  equation 

T— R x A p    * 

would  be  W"  =  " ,  p  standing  for  the  incomplete 

parts.  In  this  view  of  the  question  we  are  supported  by  the 
analogy  of  water  running  through  a  pipe  of  given  dimensions 
from  a  cistern  ;  for  however 
large  this  cistern  be,  pro- 
vided there  be  no  more 
pressure,  the  water  running 
through  the  pipe  would  be 
the  same.  So  far  as  the 
voltaic  fluid  is  concerned  I 
feel  certain,  from  numerous 
observations,  that  beyond  a 
certain  point  the  increase  of  a  battery  does  not  cause  a  greater 
amount  of  electricity  to  pass  through  a  given  resistance ;  and, 
perhaps,  in  those  cases,  where  the  enlargement  of  a  battery  in- 
creases the  voltaic  force,  the  battery  in  the  former  instance 
was  deficient  in  size  in  relation  to  the  size  of  the  resisting 
part  R,  the  tunnel,  in  fact,  having  been  defective  originally  in 
that  part.  It  is  possible  that  the  expression  for  this  con- 
dition might  be  altered ;  for  R,  the  resistance  to  the  single 

S2 


260     Mr.  Smee's  New  Definition  of  the  Voltaic  Circuit, 

voltaic  circle,  might  possibly  vary  in  some  new  manner,  for 
which  further  experiments  are  wanted.  In  that  case  it  would  be 

I'A— 151  • 

"W"  = '    the  old  English  1&  standing  for  the  new 

resistance  afforded  to  the  whole  current.  The  tunnel  might  be 
cut  away  at  any  other  part  besides  (R),  thus  it  might  be  de- 
ficient at  (F),  (a),  (c),  (r),  or  (e) ;  but  the  student  will  readily 
perceive  the  expressions  for  these  cases. 

The  algebraic  formula  for  (W)  is  replete  with  interest,  for  it 
accurately  defines  the  value  of  (W)  in  determining  the  so-called 
power  of  any  battery.  The  power  of  a  battery  is  the  inten- 
sity multiplied  by  the  quantity,  in  other  words,  I'  x  A  ;  but  our 
equations  show  that  W  is  not  equal  to  I  A  but  to  I  A  — R  A, 
and  from  that  we  deduce  that  I  A  =  W  +  R  A  ;  therefore  it  is 
impossible  by  Faraday's  voltameter  to  ascertain  the  value  of 
I'  A  at  once,  and  it  is  necessary  first  to  find  the  value  of  A. 
The  immense  mass  of  experiments  in  which  the  voltameter 
has  been  assumed  to  be  equal  to  I'  A,  must  now  be  discarded 
as  inaccurate,  and  no  deductions  drawn  from  them ;  but  all 
future  experimenters,  by  attending  to  these  equations,  may 
make  the  results  obtained  by  the  voltameter  absolutely 
correct. 

The  symbol  (A)  I  have  before  noticed  stands  for  the  value 
of  atoms  of  the  compound  fluid  exposed  to  the  action  of  a  body 
removing  one  of  its  elements.  It  sometimes  becomes  an  incon- 
stant quantity,  as  in  the  cases  where  non-conducting  substances 
incase  the  poles  of  the  battery.  A  is  tolerably  constant  in  Da- 
nielPs  and  in  Grove's  battery,  most  so  in  the  former.  It  is  less 
constant  in  mine,  and  very  inconstant  in  most  smooth  metal 
batteries.  A  is  analogous  to  what  experimenters  formerly  very 
properly  called  the  quantity  of  a  battery.  The  contact  theorists 
indeed  would  fain  make  us  believe  that  there  is  no  such  thing  as 
either  quantity  or  intensity,  but  they  have  erroneously  multi- 
plied intensity  (I')  with  quantity  (A),  and  called  it  electromotive 
power,  and  then  denied  the  existence  of  the  several  parts  of  that 
power,  which  is  nothing  but  the  I'  A  of  my  equation  with  the  (c) 
and  (r)  abstracted  from  the  (I'),  and  considered  separately. 
This  is  the  point  on  which  Ohm  and  his  followers  have 
perplexed  all  English  philosophers ;  still,  notwithstanding  this 
mystification,  to  Ohm  is  due  the  hearty  thanks  of  every  elec- 
trician for  showing  that  voltaic  force  is  diminished  by  resist- 
ances, and  doubtless  his  doctrine  of  resistance  is  a  most  im- 
portant and  lasting  discovery.  Ohm's  equation,  in  the  complex 
mannerin  which  he  has  given  it,  presents  fewest  difficulties  when 
applied  to  solid  connecting  resistances ;  thus  those  who  used  bat- 
teries with  connected  wires  could  appreciate  it  in  many  cases,  but 


•with  Formula  for  ascertaining  its  power.  26 1 

thosewhowere  engaged  in  experimentseither  in  the  construction 
of  the  voltaic  battery  itself  or  in  complex  resistances,  found  it 
perfectly  inapplicable.    By  the  equation  for  (W)  we  find  that 

W 

A  =  -p — p-  which  I  have  already  mentioned  must  be  deter- 
mined before  we  can  'find  the  value  of  I'  A,  or  what  is  properly 
called  the  power  of  any  battery. 

Sometimes  W  is  very  small,  as  in  De  Luc's  columns,  where 
the  total  amount  of  chemical  action,  although  in)  is  frequently 
500  to  1000,  is  so  small,  that  experimenters  have  even  denied 
its  existence ;  but  when  we  consider  that  these  very  persons 
assert,  that  as  soon  as  chemical  action  does  become  decidedly 
manifest,  the  action  ceases,  how  strongly  do  they  favour  our 
views !  for,  according  to  our  equation,  we  expect  (a)  to  be 
gradually  increased  till  all  action  would  be  stopped.  W,  in- 
deed, according  to  our  equation,  might  be  so  small,  as  not  to 
be  cognizable  to  our  senses  for  weeks,  months,  years,  or  cen- 
turies ;  and  yet  (I)  multiplied  by  a  very  large  (n)  would  show 
enormous  intensity  or  power  of  overcoming  resistances. 

The  present  modifications  of  the  theory  of  galvanism  are 
perfectly  consonant  with  every  practical  direction  given  in  the 
preceding  pages,  and  the  only  difference  in  the  theory  will 
be  found  irt  the  uncertainty  expressed  upon  the  contact  and 
chemical  action  theories.  Indeed,  in  page  54<  of  my  work, 
as  already  cited,  the  result  is  almost  given  in  words  though 
not  in  letters.  By  removing  the  slight  difficulties  which  ap- 
peared to  envelope  the  latter  theory,  by  showing  the  necessity 
for  a  negative  pole  to  cause  power  is  unfounded,  the  beautiful 
doctrine  of  Faraday  is  placed  on  the  surest  foundation,  and 
the  extraordinary  and  dogmatical  paradox  of  a  power  without 
a  cause  is  proved  to  be  a  fanciful  chimaera. 

With  regard  to  the  connexion  of  the  voltaic  power  with 
that  of  electricity  produced  from  other  sources,  perhaps  it 
might  be  expected  I  should  say  a  few  words.  In  the  voltaic 
battery  (I)  is  small,  but  may  be  increased  to  any  size  by  (n), 
and  as  we  have  the  power  of  increasing  (A)  also  unlimitedly, 
we  can  perform  any  amount  of  work  per  second,  indeed  we 
might  throw  down  hundreds  of  tons  of  copper  per  second,  if 
we  were  disposed  to  make  our  circuit  large  enough.  In 
frictional  electricity  (I)  is  enormous,  but  (A)  is  depressed  to  its 
utmost  limit,  so  that  not  having  a  perfect  command  over  (A) 
to  increase  it  indefinitely,  we  cannot  at  present  obtain  what 
work  we  please  in  a  given  time.  In  animal  electricity  (I)  is 
great,  (A)  is  moderately  large.  In  thermo-electricity  (I)  is 
depressed,  perhaps  increasingly,  so  that  although  (A)  and  (n) 
may  be  multiplied  indefinitely,  yet,  practically,  we  should  never 
be  able  thoroughly  to  overcome  the  smallness  of  (I).     In  that 


262      Mr.  Smee's  New  Definition  of  the  Voltaic  Circuit. 

mighty  operation  of  Nature  which  has  just  occurred,  where  the 
noise  accompanying  the  discharge  of  the  electricity  over  the 
metropolis  was  so  awful  as  to  alarm  not  only  delicate  females, 
but  the  stoutest  hearts  of  men,  and  even  the  heretofore  un- 
terrified  nervous  system  of  infants — in  that  terrific  storm, 
when  every  living  creature  trembled,  and  Nature  seemed  al- 
most alarmed  at  her  own  operations,  how  vast  was  (I)  !  how 
large  (A) !  Could  I  therefore  but  have  imprisoned  that 
collection  of  force  which  in  discharging  itself  committed  such 
devastation  on  houses,  churches,  and  trees,  and,  having  en- 
cased it,  been  able  to  have  let  it  loose  as  it  might  have  been 
required;  then  indeed  would  all  batteries  have  been  henceforth 
discarded  as  playthings  for  children — philosophical  toys  to  be 
admired,  still  despised,  for  (I  A)  being  unlimitedly  great,  we 
could  obtain  what  work  we  pleased  in  any  given  time,  at  no 
expense. 

The  estimate  of  the  parts  of  (I)  in  other  cases  where  force 
is  produced,  i.  e.  an  electricity  not  proved  to  be  derived  from 
chemical  action,  I  do  not  deem  it  my  business  now  to  consider, 
but  great  difficulties  would  attend  its  accurate  investigation, 
as  it  is  almost  impossible  to  magnify  the  size  of  the  circle  in 
these  cases,  in  such  a  way  as  to  make  the  action  in  each  part 
cognizable  by  our  senses.  It  is  however  quite  evident,  that  as 
in  the  voltaic  and  thermo  circuits  (I)  may  be  magnified  to 
any  extent  by  (n),  that  the  power  of  (1)  in  every  case  might 
be  brought  to  the  same  standard  in  the  power  overcoming  the 
resistances  R',  R",  R'",  &c. 

The  obstacles  to  the  completion  of  the  voltaic  circuit  (O), 
are  made  up  as  we  have  seen  of  several  parts,  a,  e,  r,  c,  but, 
although  they  differ  in  kind,  still  as  they  have  similar  resisting 
properties,  a  perfect  table  might  be  made,  referring  them  to 
one  given  standard,  showing  the  separate  value  of  each.  The 
principle  on  which  it  should  be  constructed,  is  the  law  of  the 
completion  of  the  voltaic  current,  detailed  when  treating  of 
the  reduction  of  alloys ;  and  as  soon  as  we  have  this  table 
accurately  and  numerically  drawn  up,  the  principles  of  the 
passage  of  the  voltaic  circuit,  which  formerly  puzzled  the  most 
enlightened  experimenters,  will  be  rendered  certain,  and  the 
difficulties  will  be  also  reduced  to  the  facility  and  certainty 
of  common  arithmetic.  Having  obtained  perfect  tables  of 
(O)  and  its  several  parts,  we  can  readily  obtain  the  relative 
value  of  (I),  derived  from  various  sources,  by  finding  out 
what  extent  of  (O)  neutralizes  each  individual  (I),  and  the 
value  of  (I),  or  the  force  of  any  battery,  will  be  determined 
with  equal  facility.  Complete  tables  of  (O)  and  (I)  now  be- 
come the  greatest  desiderata,  not  only  to  electro-metallurgists, 
but  to  all  who  use  the  voltaic  battery. 


Prof.  Kelland  on  the  Theory  of  Molecular  Action,    263 

I  now  bid  adieu  to  my  theory  of  galvanism  and  my  formulae 
and  to  those  who  have  neither  time  nor  inclination  to  dive 
into  these  mysteries,  I  would  say, — remember,  in  all  operations 
that  the  sum  of  the  resistances  does  not  exceed  the  sum  of  the 
intensities ;  and  that  in  increasing  the  circuit,  every  part  is 
equally  enlarged : — to  those  who  have  devoted  themselves  to 
these  properties — remember  they  will  be  useless  if  not  brought 
into  active  operation ;  thus,  if  any  difficulty  occurs  in  your 
voltaic  circuit,  refer  it  at  once  to  its  proper  head,  and  the 
operator  may  be  sure  that  a  continual  practice  and  habit  of 
using  these  formulas  will  enable  him  to  conduct  his  proceedings 
with  a  certainty  never  obtainable  by  blind  experiment. 

In  concluding  these  formulae,  I  herewith  leave  theory  and 
rationale  altogether,  for  having  completed  the  principles,  as 
far  as  I  am  capable,  of  everything  relating  to  electro-metal- 
lurgy, I  shall  enter  at  once  into  the  applications  of  the  science 
for  the  direct  purposes  of  the  arts ;  and  although  everything 
that  will  be  contained  in  the  subsequent  parts  of  this  work  has 
already  been  .comprised  in  the  parts  already  finished,  yet  there 
are  many  little  practical  difficulties  to  be  surmounted — many 
little  circumstances  to  be  pointed  out  which  the  operator  is 
likely  to  overlook  or  forget  in  conducting  his  operations,  and 
these  are  the  circumstances  to  which  the  concluding  pages 
will  more  especially  be  devoted.  Henceforth  the  work  will 
be  entirely  practical,  as  heretofore  it  has  been  exclusively 
theoretical.  There  is  a  reproach  attached  to  the  very  word, 
theory ;  the  sense  in  which  it  is  employed  means  rather  ratio- 
nale than  theory,  for  whilst  it  has  been  my  constant  endea- 
vour to  shun  theories  without  facts,  I  have  tried  and  tried 
hard  to  generalize  all  extensive  series  of  facts,  and  to  give  the 
rationale  of  every  circumstance  which  is  likely  to  occur  to  the 
operator. 

XLV.  Reply  to  some  Objections  against  the  Theory  of  Mo- 
lecular Action  according  to  Newton's  Law.  By  the  Rev.  P. 
Kelland,  M.A.,  F.R.SS.  L.  $  E.,  F.C.F.S.,  $c,  Professor 
of  Mathematics  in  the  University  of  Edinburgh,  late  Fellow 
and  Tutor  of  Queen's  College,  Cambridge. 
[Continued  from  p.  208.] 

MR.  EARNSHAWS  first  argument  is,  "  Dispersion  in 
a  refracting  medium  cannot  be  accounted  for  on  the  finite- 
interval  theory,  unless  there  be  also  dispersion  in  vacuo.  Now 
as  there  is  no  dispersion  in  vacuo,  I  infer  generally,  that  the 
finite-interval  theory  cannot  account  for  dispersion"  (pres.  vol. 
p.  47). 

The  difficulty  which  is  here  brought  forward  is  the  same 


264;     Prof.  Kelland's  Reply  to  some  Objections  against  the 

that  has  so  often  been  started ;  it  in  fact  goes  to  the  foundation 
of  the  Jinite-interval  theory.  If  that  theory  be  supposed  to 
consist  in  the  hypothesis,  that  the  vibrations  of  the  particles 
of  aether  within  a  medium  are  unaffected  by  the  presence  of 
the  particles  of  matter  in  any  shape,  I  shall  not  undertake  to 
be  its  advocate.  I  will  simply  refer  to  M.  Cauchy's  Memoir 
(Prague),  p.  188.  But  it  is  evident  that  Mr.  Earnshaw 
admits  into  that  theory  the  indirect  action  of  the  particles  of 
matter ;  for  he  says,  "  I  have  not  taken  account  of  the  direct 
action  of  matter  upon  the  aether ;  but  as  my  results  are  inde- 
pendent of  arrangement,  it  is  obvious  that  the  indirect  effect 
of  matter  is  included  in  them.  Consequently  the  indirect 
effect  of  matter  never  can  assist  us  in  accounting  either  for  the 
transversality  of  vibrations  or  for  dispersion"  (p.  48).  lam 
obliged  to  ask  Mr.  Earnshaw  what  he  conceives  to  be  the  di- 
rect effect  of  matter.  The  phrase  was,  I  think,  originated  by 
myself,  and  was  meant  to  express  the  attractions  or  repulsions 
of  the  quiescent  particles  of  matter  on  those  of  aether.  If  this 
be  the  sense  in  which  Mr.  Earnshaw  uses  the  phrase,  then  I 
must  understand  from  the  above  quotation  that  he  has  not  es- 
timated the  direct  action  of  the  particles  of  matter,  simply 
because  he  has  assumed  that  those  particles  vibrate,  or  rather 
perhaps,  because  he  has  assumed  that  they  vibrate  respectively 
in  precisely  the  same  manner  as  the  particles  of  aether  would 
do  if  they  filled  the  same  place.  If  this  be  the  case,  indeed, 
whatever  Mr.  Earnshaw  assumes,  the  expressions  for  the  ve- 
locity of  transmission  must  contain  a  term  due  to  the  action  of 
the  particles  of  matter.  Let  us  even  take  the  extreme  case  of 
supposing  that  these  particles  are  at  rest,  and  that  their  attrac- 
tions or  repulsions  produce  no  effect :  still  is  there  an  indirect 
effect  due  to  them,  which  although  not  easily  calculated,  is 
clearly  of  the  utmost  importance.  I  allude  to  the  effect  due 
to  the  want  qf  action  of  particles  of  aether  in  the  portions  of 
space  occupied  by  the  material  particles.  Neither  this,  nor 
the  pressure  of  the  particles  of  matter  on  the  adjacent  particles 
of  aether  tending  to  stop  their  motion,  does  Mr.  Earnshaw  say 
one  word  about;  and  yet  he  asserts  "  that  the  indirect  effect 
of  matter  is  included  in  his  equations."  How  is  it  included  ? 
If  it  be  replied,  that  the  equations  in  p.  47  are  supposed  to 
contain  terms  dependent  on  the  particles  of  matter,  then  is  it 
evident  that  Mr.  Earnshaw's  argument  is  an  antithesis  to  his 
premises;  the  latter  being  the  expressions  for  the  velocity  of 
transmission  in  vacuo  and  in  a  refracting  medium  are  different 
in  form,  the  former,  therefore  the  velocities  themselves  must 
have  the  same  form.  Now  as  I  am  not  willing  to  accuse  Mr. 
Earnshaw  of  any  such  reasoning,  I  am  anxious  to  imagine  on 


Theory  of  Molecular  Action  according  to  Newton's  Law,  265 

what  his  argument  it  based.     I  can  only  conceive  it  to  be  the 
assumption  that  the  equation 

can  in  no  case  render  y  dependent  on  A.  That  Mr.  Earn- 
shaw  admits  it  does  not  in  vacuo,  is  evident  from  the  fact  that 
he  believes  the  equations  he  has  deduced  to  be  correct  in  that 
case.  He  says,  Phil.  Mag.,  May,  p.  373,  "  these,  then,  are  the 
equations  of  transmission  of  common  light  through  any  transpa- 
rent medium  whatever."  If  I  am  right  in  my  conjecture,  then, 
I  reply  that  Mr.  Earnshaw  is  not  at  liberty  to  base  so  sweep- 
ing an  argument  as  he  brings  forward  on  any  assumption 
whatever,  much  less  on  one  so  little  likely  to  be  correct.  I  re- 
peat, that  I  am  unwilling  to  suppose  that  Mr.  Earnshaw  has 
made  use  of  any  false  reasoning,  but  I  am  convinced  that  any 
one  who  shall  peruse  his  paper  will  agree  with  me  in  affirming, 
that  with  so  few  words  devoted  to  explaining  the  influence  of 
the  particles  of  matter  it  is  utterly  impossible  for  any  one  to 
know  what  Mr.  Earnshaw  does  mean.  I  am  the  more  anxious 
to  express  this  fully,  that  I  may  not  be  accused  of  misinter- 
preting the  argument,  and  I  trust  it  will  have  the  effect  of 
eliciting  a  more  full  and  satisfactory  statement. 

On  the  next  remark  of  Mr.  Earnshaw  I  shall  not  dwell.  It 
has  reference  to  the  promised  proof  by  Mr.  O'Brien,  that  "the 
hypothesis  of  finite  intervals  cannot  be  correct,"  and  to  the 
adoption  of  the  hypothesis  of  the  direct  action  of  the  particles 
of  matter.  I  shall  only  observe,  that  so  far  as  I  can  see,  the 
application  of  this  hypothesis  is  insufficient,  unless  it  be  ad- 
mitted that  the  particles  of  "  matter  are  compound,  consisting 
of  many  different  atoms,"  all  of  which  vibrate  along  with  the 
particles  of  aether.  If  you  allow  the  same  assumptions  to  the 
finite-interval  theory,  it  will  account  for  the  same  facts  by  a 
formula  very  much  of  the  same  kind.  It  is  by  this  means  that 
I  accounted  for  dispersion  in  my  'Theory  of  Heat,'  p.  152. 
The  equations  of  motion  of  two  sets  of  vibrating  particles  were 
first  obtained  by  me  in  the  Transactions  of  the  Cambridge 
Philosophical  Society,  p.  237  et  seq. 

The  next  matter  to  which  I  will  direct  attention  has  more 
pointed  reference  to  myself.  Mr.  Earnshaw,  in  a  paper  printed 
in  the  Philosophical  Magazine  for  April,  points  out  the  pro- 
cess which  I  had  adopted  in  my  first  Memoir  on  Dispersion, 
and  adds,  "  the  remaining  four  lines  are  used  as  a  test  of  the 
truth  of  the  undulatory  theory^'  (P«  308).  Where,  and  by 
whom,  he  does  not  state.  For  my  own  part,  I  disclaim  any 
such  unphilosophical  opinion.     What  I  hold  is  this :  "  that 


266    Prof.  Kelland's  Reply  to  some  Objections  against  the 

a  theory  which  has  succeeded  so  well  in  accounting  for  a  great 
variety  of  intricate  and  delicate  phenomena"  (Earnshaw,  p. 
304),  is  strengthened  by  the  removal  of  any  obstacle,  and  con- 
sequently by  bringing  under  it  the  explanation  of  the  pheno- 
menon of  dispersion.     But  has  the  phenomenon  been  ex- 
plained ?  I  answer,  most  assuredly.  It  is  done  as  satisfactorily 
as  almost  any  one  phenomenon  in  nature  is  explained.     Its 
doubtful  nature,  the  "uncertainty  J"  which  I  mentioned  in  my 
'Theory  of  Heat'  as  attached  to  it,  is  referable,  not  to  the  kindof 
explanation,  but  to  its  detail.  Nay,  even  Mr.  Earnshaw  himself 
appears  to  look  for  a  complete  explanation  to  the  very  quarter 
at  which  he  aims  his  objections.  Unless  Mr.  Earnshaw  adopts 
the  hypothesis  that  the  particles  of  matter  are  at  rest,  there  is 
no  difference  whatever  between  the  hypothesis  of  Mr.  O'Brien, 
which  he  designates  as  a  "  more  promising  one,"  and  my  own. 
Are  my  equations  then  incorrect,  and  why  ?     I  see  them  open 
at  p.  248  of  vol.  vi.of  the  Transactions  of  the  Camb.  Phil.  Soc, 
they   are   certainly   not   of  exactly  the   same  form  as  Mr. 
O'Brien's ;  but  his  are  only  approximations.     1  do  not  say 
that  even  then  they  are  identical,  the  difference  probably  will 
be  removed  by  supposing  B  and  B  equal  in  the  latter.     So  far 
as  I  am  concerned  with  the  numerical  verification  of  the  for- 
mulas for  dispersion  (which  occupies  between  five  and  six 
pages  in  my  Memoir),  I  may  state  that  it  is  essential  to  show 
that  our  results  are  in  the  form  which  the  phenomena  require 
they  should  be  :  and  having  premised  this,  I  will  gladly  answer 
the  questions  which  Mr.  Earnshaw  puts  me  in  p.  49. 

"  Am  I  to  understand  him  to  say,  that  his  formule  are  of 
necessity  capable  of  producing  correct  results  even  if  the  data 
employed  be  erroneous  ?"  Yes :  but  the  data  are  not  erro- 
neous. 

"  May  I  then  ask,  what  is  the  nature  of  the  connexion  of 
these  formule  with  theory  ?  and  in  what  degree  is  his  theory 
supported  and  strengthened  by  coincidences  obtained  from 
such  formule?"  The  numerical  verifications  were  used,  as 
is  stated  at  the  place,  as  a  test  of  the  general  accuracy  of  the 
deductions.  Let  me  quote  my  own  words.  "  Results  more 
nearly  agreeing  might  doubtless  be  obtained  by  proceeding  to 

one  place  further  in  the  expansion  of  sin  — °,  but  the  above 

will  suffice  to  establish  the  general  accuracy  of  the  formula" 
(p.  174).  "  If,  however,  it  were  requisite  to  determine  accu- 
rately the  values  of/>,  a , . . . .  of  course  the  plan  to  be  adopted 
would  be  that  of  introducing  seven  constants,  and  determining 
their  values  from  the  seven  given  equations"  (pp.  172-3). 
"  I  wish  to  ask,  then,  how  the  results  could  have  any  power 


Theory  of  Molecular  Action  according  to  Newton's  Law.  267 

at  all  in  confirming  the  theory,  if  the  formulae  were  of  necessity 
capable  of  producing  correct  results  from  correct  or  incorrect 
data  indifferently?" 

In  answering  this  question,  I  must  premise  that  I  fear  I  do 
not  rightly  understand  what  Mr.  Earnshaw  means  by  "  from 
correct  or  incorrect  data  indifferently."  Perhaps  I  shall  make 
the  matter  more  clear  by  putting  an  hypothetical  case.  The 
formula  being  general,  admitting  as  many  arbitrary  constants 
as  you  please,  is  sufficient  to  satisfy  any  numerical  results  con- 
tinuous and  not  inconsistent  with  each  other.  This  I  presume 
will  be  allowed.  Suppose,  then,  the  results  had  been  exactly 
the  converse  of  what  they  are :  suppose  /n  to  have  increased 
with  A.  The  formula,  then,  could  probably  never  have  been 
made  apparently  applicable;  and,  although  sufficient,  would 
assuredly  have  been  held  as  not  at  all  probably  true.  By  re- 
versing the  process,  and  showing  that  a  formula  not  only  sa- 
tisfies the  requisite  demand,  but  does  so  in  the  most  simple 
manner,  we  certainly  add  weight  to  its  authority,  and  strengthen 
the  process  on  which  it  is  founded. 

I  proceed  now  to  the  consideration  of  the  other  objections 
which  Mr.  Earnshaw  has  adduced,  for  the  most  part  to  my 
own  results,  in  the  same  paper.  They  all  originate  in  one 
and  the  same  error  which  Mr.  Earnshaw  has  fallen  into  in 
deducing  his  equations  at  p.  47.  I  dare  say  Mr.  Earnshaw 
has  himself  discovered  the  oversight  ere  now,  and,  but  that  he 
has  wielded  the  erroneous  results  to  which  it  led  him  in  dealing 
blows  most  at  my  conclusions,  I  should  have  left  it  to  himself 
to  supply  the  correction :  but  as  Mr.  Earnshaw  has  set  his 
conclusions  in  opposition  to  the  truth  of  my  deductions,  and 
those,  too,  of  the  most  important  kind,  I  cannot  delegate  the 
power  of  replying  to  his  own  convictions.  The  error  I  allude  to 
is  this.  Mr.  Earnshaw  says,  "  We  are  now  at  liberty,  without 
affecting  the  generality  of  our  investigations,  to  suppose  that 
the  axes  of  symmetry  were  the  coordinate  axes  employed  in  my 
former  paper ;  in  which  case  D  =  E  =  F  =  0,"  &c.  (p.  47). 
Now  it  is  not  at  all  true  that  because  the  axes  are  axes  of 
symmetry  therefore  D  =  E  =  F  =  0.  The  method  which 
Mr.  Earnshaw  has  employed  in  his  former  paper  (Phil.  Mag. 
May,  p.  373)  to  obtain  his  equations,  is  more  similar  to  that 
which  M.  Cauchy  uses  to  obtain  the  same  equations  in  his 
recent  publications,  than  to  his  original  method.  In  his  Nou- 
veaux  Exercises,  p.  4,  for  instance,  he  makes 

as  Mr.  Earnshaw  does,  without  giving  explicitly  the  value  of  F. 


268     Prof.  Kelland's  Reply  to  some  Objections  against  the 

But  in  his  Memoire  sur  la  Dispersion  de  la  Lumiere  (Prague), 
he  gives  the  value  of  F  as 

^  f2mfr  .  2   &rcos&\   .     n\ 

S  \—f— cos z3 cos y sin •  — 2 —  J"  ^p"    * 

Had  Mr.  Earnshaw  seen  this  last  value,  he  would  hardly  have 
conceived  that  it  could  be  made  zero  by  the  symmetry  of  the 
axes  :  he  would  have  been  convinced  that  the  relative  values 
of  /3,  y,  and  8,  i,  e.  the  relative  directions  of  transmission  and 
of  the  axes,  alone  could  effect  that  object.  The  fact  is,  that  if 
any  one  of  the  axes  of  coordinates  coincide  with  that  of  trans- 
mission, the  three  quantities  do  vanish ;  in  other  cases  they 
do  not.  Mr.  Earnshaw's  oversight  consists,  then,  in  assigning 
to  an  axis  of  symmetry  a  property  which  belongs  only  to  the 
axis  of  transmission.  It  is  remarkable  that  Mr.  Earnshaw  did 
not  inquire  into  the  cause  of  difference  between  his  equations 
and  mine,  for  in  form  they  are  identical.  [See  Phil.  Mag., 
May,  1837,  p.  388,  and  various  other  places.]  I  say  it  is  re- 
markable, for  Mr.  Earnshaw  perceived  that  the  cause  of  differ- 
ence lay  in  the  dependence  or  want  of  dependence  of  the  equa- 
tions of  motion  on  the  direction  of  transmission.  All  the 
argument  he  offers  in  support  of  his  view  is  contained  in  the 
following  words: — "Again,  by  referring  to  my  former  com- 
munication, it  will  be  seen  that  the  equations  of  motion  do  not 
depend  upon  the  position  of  the  front  of  the  waves  traversing 
the  medium"  (p.  47).  And  this  is  in  reality  all  the  reasoning 
on  which  he  founds  his  remarks  subversive  of  so  many  of  my 
conclusions.  One  word  will  serve  to  answer  it.  Mr.  Earn- 
shaw's  former  communication  did  not  contain  the  equations  of 
motion  on  which  his  arguments  are  founded.  These  are  to 
be  found  only  in  the  latter  communication,  and  in  a  form 
which  does  depend  on  the  position  of  the  front  of  the  wave. 
Having  then  shown  that  Mr.  Earnshaw's  argument  is  founded 
in  a  mistake,  I  will  adopt  his  language  (p.  48),  modified  to 
suit  my  own  purpose : — 

I  consider  it  therefore  as  proved  incontestably,  that  according 
to  the  finite-interval  theory  there  is  a  connexion  between  the 
directions  of  the  vibrations  and  the  law  of  molecular  force.  Hence, 
then,  I  have  established  the  transversality  of  vibrations  on  that 
theory  on  a  basis  which  defies  opposition. 

Having  thus  shown  that  an  error  lies  at  the  foundation  of 
all  Mr.  Earnshaw's  objections,  it  might  be  deemed  unneces- 
sary to  refute  them  in  detail :  yet  since  they  are  so  plainly  and 
prominently  brought  forward  as  opposed  to  my  conclusions,  I 
owe  it  to  myself  briefly  to  do  so.     They  are, — 

1.  "The  vibrations  have  no  necessary  reference  to  the  di- 


Theory  of  Molecular  Action  according  to  Newton's  Law.   269 

rection  of  transmission."     This  is  assumed  by  Mr.  Earnshaw 
when  he  omits  D,  E,  and  F,  and  hence  all  his  objections. 

2.  "  There  can  be  no  connexion  between  the  directions  of 
the  vibrations  and  the  law  of  molecular  force."  It  has  been 
proved  by  me  in  the  Transactions  of  the  Cambridge  Philoso- 
phical Society,  vol.  vi.  p.  180,  and  Philosophical  Magazine, 
May,  1837,  p.  841,  that  if  the  law  of  force  in  a  medium  of 
symmetry  be  that  of  the  inverse  square  of  the  distance,  the 
vibrations  must  be  altogether  transversal  or  altogether  normal. 
I  call  on  Mr.  Earnshaw  to  point  out  an  error  in  my  reasoning. 

3.  But  Mr.  Earnshaw  has  attempted  to  impugn,  not  in- 
deed my  reasoning,  but  my  inference.  He  says  (p.  49,  last 
line),  "  since  v  v'  v"  are  the  velocities  of  the  wave,  and  not  of 
the  particles,  the  inference  should  have  been,  that  there  is  one 
direction  in  which  waves  cannot  be  transmitted',  or,  in  other 
words,  that  the  cether  is  opa/ce  in  one  direction."  Mr.  Earn- 
shaw ought,  I  repeat,  to  have  attempted  to  show  that  there  is 
some  error  in  the  argument,  for  he  must  know  that  such  an 
inference  as  he  draws  tends  to  throw  discredit  (if  legitimate) 
upon  any  reasoning  from  which  it  is  made  to  follow.  The 
hypothesis  is  that  the  aether  is  equally  affected  in  all  directions, 
the  conclusion,  that  it  is  opake  in  one. 

The  inference,  however,  cannot  follow  from  my  equations, 
for  Mr.  Earnshaw  will  see,  if  he  turns  to  my  Memoir,  that  o' 
is  the  velocity  of  a  normal  vibration  which  is  assumed  to  exist. 
Since  then  (I  argue)  the  normal  vibration  has  not  a  possible 
velocity  of  transmission,  it  does  not  exist.  In  fact,  if  there  be 
a  normal  motion  at  all  it  must  be  a  transmissory  one,  due 
to  exponential  in  place  of  circular  functions.  On  this  last  fact 
I  have  based  my  Theory  of  Heat  (Preface,  p.  8,  and  Me- 
moirs, Sec, passim).  Since  Mr.  Earnshaw  quotes  Mr.  O'Brien, 
I  will  refer  him  to  the  same  quarter  to  be  set  right,  for  his 
conclusions  are  equally  controverted  by  Mr.  Earnshaw's  ob- 
jections. 

4.  "  But  I  am  unable  to  discover  on  what  ground  it  is  stated 
that  y'  is  impossible,"  &c.  Had  Mr.  Earnshaw  read  through 
the  page  he  refers  to  he  would  have  found  the  reason  :  all  that 
he  suggests  is  there  plainly  discussed,  the  inference  that  the 
cether  is  opa/ce  in  one  direction  only  excepted. 

5.  Mr.  Earnshaw  concludes  with  a  suggestion  that  the  in- 
ference ought  rather  to  have  reference  to  the  instability  of  the 
medium  according  to  the  Newtonian  law.  How  he  connects 
the  impossibility  of  transmission  of  an  assumed  vibration  with 
instability  it  is  easy  to  see,  and  that  it  arises  from  the  assump- 
tion of  the  want  of  dependence  of  the  equations  of  motion  on 
the  direction  of  transmission.    But  I  shall  not  dwell  on  this 


270  Mr.  W.  H.  Balmain  on  the  Formation  of  Compounds  of 

subject  here.  It  has  already  been  amply  dealt  with  at  the 
commencement  of  my  reply  :  I  will  only  add,  when  it  is  con- 
cluded from  the  hypothesis  of  a  cubical  arrangement  of  the 
particles,  acting  by  forces  which  vary  according  to  the  New- 
tonian law,  that  the  direction  of  one  side  of  the  cube  is  stable 
and  of  one  unstable  (Earnshaw  on  the  Nature  of  Molecular 
Forces,  Art.  15),  ought  we  not  to  ask,  Is  it  the  hypothesis,  or 
the  reasoning  based  on  it  which  is  erroneous  ?  Must  it  not  of 
necessity  be  the  latter  ? 

We  have  now  done  with  the  objections  to  the  statical  pos- 
sibility of  the  law.  It  remains  to  reply  to  the  two  objections 
to  its  dynamical  applicability.  It  is  fit  that  a  matter  so  im- 
portant as  the  rejection  of  a  law  which  explains  so  many  phe- 
nomena (see  Gauss,  in  the  last  No.  of  the  Scientific  Memoirs), 
which  has  so  strong  an  d  priori  probability,  and  which  is  the 
proved  law  of  material  action,  should  rest  on  none  but  the 
most  unexceptionable  evidence.  Whatever  may  become  of 
the  question  ultimately,  I  trust  that  by  rigidly  examining  that 
evidence  which  has  been  afforded  and  showing  its  inadequacy, 
I  shall  be  considered  as  actuated  by  no  captious  or  unphilo- 
sophical  spirit.  My  next  communication  will  be  a  reply  to 
M.  Cauchy,  whose  arguments  being  based  on  a  refined  ana- 
lysis, can  scarcely  be  answered  without  the  use  of  similar 
means. 

[To  be  continued.] 

XL  VI.  Observations  on  the  Formation  of  Compounds  of  Boron 
and  Silicon  with  Nitrogen  and  certain  Metals.  By  W.  H. 
Balmain,  Esq.,  Lecturer  on  Chemistry  in  the  Mechanics' 
Institution,  Liverpool*. 

/CONSIDERING  the  strong  affinity  existing  between  hy- 
^  drogen  and  nitrogen,  and  between  carbon  and  nitrogen, 
together  with  the  circumstances  under  which  they  will  com- 
bine, and  their  chemical  relations  to  boron  and  silicon,  I  was 
led  to  imagine  that  the  two  latter  elements  must  have  a  very 
strong  affinity  for  nitrogen,  and  concluded  that  they  might 
be  caused  to  combine  with  it  by  double  decomposition ;  and, 
bearing  in  mind  the  strong  affinities  of  ammonia  and  cyano- 
gen, it  appeared  probable  that  the  compounds,  if  obtained, 
would  play  an  important  part  as  chemical  agents ;  and  I  had 
hopes  that  some  of  the  bodies  at  present  supposed  to  be  ele- 
mentary might  prove  to  be  compounds  of  nitrogen  with  these 
or  other  elements.  Some  experiments  instituted  to  establish 
these  points  have  been  in  a  measure  successful,  but  as  they 
form  only  a  small  part  of  the  great  number  which  will  at  once 
*  Communicated  by  Dr.  Kane. 


Baron  and  Silicon  with  Nitrogen.  271 

suggest  themselves  to  the  mind  of  the  chemist,  and  as  my  time 
is  of  necessity  devoted  to  other  objects  and  my  means  very 
limited,  I  beg  leave  to  lay  the  few  facts  which  I  have  been 
able  to  ascertain  before  the  working  chemists  of  the  day  through 
the  medium  of  the  Philosophical  Magazine. 

Silica  and  boracic  acid  undergo  no  change  when  heated 
in  ammoniacal  gas  by  means  of  the  oxyhydrogen  flame  nearly 
to  the  point  at  which  platina  melts,  but  when  heated  to  that 
temperature  with  cyanide  of  potassium  instead  of  ammonia, 
apparent  action  ensues.  Boracic  acid  and  cyanide  of  potas- 
sium, in  the  proportion  of  two  atoms  of  the  former  to  three 
of  the  latter,  were  placed  in  a  covered  porcelain  crucible,  that 
inclosed  in  a  larger  Hessian  crucible,  and  the  space  between 
being  filled  with  small  pieces  of  charcoal,  the  whole  was  heated 
to  whiteness  in  a  wind  furnace.  The  result  was  a  white  porous 
substance,  which  was  found  not  only  at  the  bottom  of  the  cru- 
cible, but  also  lining  the  sides  and  the  top,  having  been  carried 
there  by  spurious  sublimation.  The  relative  quantities  given 
above  were  used  in  order  that  the  carbon  of  the  cyanide  might 
be  exactly  in  the  right  proportion  for  taking  all  the  oxygen  from 
the  boracic  acid  and  forming  carbonic  oxide  only,  and  when 
by  accident  an  excess  of  boracic  acid  or  cyanide  was  employed 
it  appeared  to  remain  as  an  impurity  in  the  white  solid;  but 
these  points  were  not  closely  examined,  because  the  white  solid, 
which  was  homogeneous  and  evidently  a  distinct  and  stable 
compound,  was  a  more  interesting  object  of  study.  The  fol- 
lowing is  the  best  process  for  preparing  it : — Take  seven  parts 
of  finely  powdered  anhydrous  boracic  acid  and  twenty  parts 
of  cyanide  of  potassium  free  from  water,  and  as  far  as  possible 
from  cyanide  of  potass  and  iron  ;  and  having  lined  a  Hessian 
crucible  with  a  paste  of  powdered  charcoal  and  gum,  and 
heated  it  until  all  water  has  passed  away,  place  the  mixture 
in  the  crucible,  cover  it  by  inverting  and  luting  a  smaller  cru- 
cible over  it,  and  heat  it  to  whiteness  for  an  hour :  it  is  ad- 
visable to  use  a  crucible  as  a  cover,  that  there  may  be  suffi- 
cient room  for  spurious  sublimation,  and  the  vent-hole  should 
be  bored  in  the  bottom  of  this  crucible  and  not  in  the  luting 
at  the  side;  and  further,  to  avoid  the  penetration  of  oxygen 
to  the  materials,  it  is  well  to  line  the  upper  crucible  in  like 
manner  with  the  lower.  The  result  found  in  both  crucibles, 
when  washed  and  dried,  will  be  the  white  solid  in  a  state 
of  purity.  It  is  a  light  porous  solid  which  readily  falls  to 
powder,  and  when  compressed,  presents  that  peculiar  sur- 
face which  is  observable  in  some  of  the  precipitated  cyanu- 
rets,  and  in  a  slight  degree  in  chloride  of  silver,  and  in 
some  iodides,  &c. ;  it  is  infusible,  insoluble,  even  when 
heated,  in  water,  in  solution  of  potass,  hydrochloric  acid,  sul- 


272     Mr.  W.  H.  Balmain  on  the  Formation  of  Compounds  of 

phuric  acid  (strong  and  diluted),  nitric  acid,  and  solution  of 
chlorine ;  it  is  not  altered  upon  exposure  to  air,  nor  does  it 
affect  the  most  delicate  turmeric  paper  when  left  upon  it  in  a 
moist  state.  Passing  over  for  the  present  the  remarkable  sta- 
bility of  this  compound,  these  characters  are  important  as 
proving  the  absence  of  boracic  acid  and  cyanide  of  potassium 
(with  some  results  it  was  found  necessary  to  wash  away  the 
excess  of  cyanide  of  potassium;  but  this  does  not  interfere 
with  the  nature  of  the  white  solid,  and  was  not  necessary 
when  the  boracic  acid  and  cyanide  of  potassium  were  quite 
pure  and  free  from  water,  and  their  proportions  very  carefully 
adjusted).  Heated  with  hydrate  of  potass  or  soda  it  yields 
ammonia  abundantly ;  in  the  deoxidizing  flame  of  the  blow- 
pipe it  is  not  altered,  nor  does  it  communicate  any  colour  to 
the  flame,  but  in  the  oxidizing  flame  it  gives  a  strong  green 
colour,  and  gradually  fuses,  yielding  a  perfect  bead,  which  is 
transparent,  hot  and  cold,  and  when  placed  with  a  drop 
of  water  upon  test  papers,  turned  tumeric  brown,  and  red 
litmus  blue.  When  the  outside  flame  impinges  upon  a 
large  surface  of  the  substance  in  powder,  as  when  a  glass  tube 
soiled  with  it  is  held  at  the  extreme  point  of  the  flame,  it  pre- 
sents a  beautiful  green  phosphorescence,  owing  no  doubt  to 
the  gradual  formation  of  boracic  acid  at  the  surface,  and  if 
it  be  removed  to  the  inner  flame,  the  centre  will  incandesce, 
while  the  outer  edges,  where  it  meets  with  the  oxygen  of  the 
air,  will  still  yield  the  elegant  green.  When  thrown  upon 
fused  chlorate  of  potass  it  deflagrates  with  a  soft  green 
light,  and  it  will  also  deflagrate  with  nitrate  of  potass. 
It  is  not  altered  by  being  gently  heated  with  potassium  or 
sodium,  nor  when  heated  before  the  blowpipe  on  charcoal, 
with  lead,  zinc,  &c.  Chlorine  has  no  action  upon  it  at  a  low 
red  heat,  and  iodine,  sulphur  and  corrosive  sublimate  may  be 
sublimed  from  it  without  decomposing  it.  It  is  not  decom- 
posed by  hydrogen  at  a  red  heat,  but  below  that  temperature 
is  decomposed  with  the  evolution  of  ammonia  by  the  vapour 
of  water,  or  by  any  substance  which  will  yield  water,  as 
hydrate  of  potass,  hydrate  of  lime,  common  clay,  hydrated 
phosphoric  acid,  and  the  rhombic  phosphate.  It  is  not  de- 
composed by  hydrochloric  acid  at  a  low  red  heat,  and  I  think 
it  is  not  altered  by  hydrofluoric  acid,  for  a  small  portion  of  it 
was  mixed  with  a  large  quantity  of  fluorspar,  with  more  than 
sufficient  sulphuric  acid  to  make  it  all  into  hydrofluoric  acid, 
and  heated  as  long  as  fumes  passed  offj  when,  after  the  sul- 
phate of  lime  had  been  washed  away  with  dilute  nitric  acid,  it 
still  yielded  ammonia  with  hydrate  of  lime. 

From  some  of  these  facts  it  appears  that  the  compound  con- 
tains boron,  nitrogen,  and  potassium,  and  I  suppose  that  the 


Boron  and  Silicon  with  Nitrogen.  21 S 

nitrogen  and  boron  are  united,  and  that  the  compound  so 
formed  is  combined  by  a  very  strong  affinity  with  potassium. 
My  inability  to  obtain  a  better  balance  than  such  as  I  could 
construct  myself  of  wood  and  paper,  or  suitable  apparatus  for 
an  analysis,  prevents  me  from  speaking  at  all  positively  as  to 
the  proportion  of  the  elements ;  but  some  analyses  and  decom- 
positions seem  to  point  out  the  proportion  K3  N3  B2  as  the 
correct  one,  from  which  it  would  appear  that  during  its  pre- 
paration there  is  no  loss  either  of  potassium  or  of  nitrogen; 
nothing  passing  off  but  carbonic  oxide : 

(2  B  Oa  and  3  (N  C2  +  K)  =  N3  B2  K3  and  6  C  O). 

This  theory  very  nearly  agrees  with  several  estimations  of 
the  quantity  of  ammonia  and  boracic  acid  found  when  the 
compound  is  decomposed  by  the  hydrates  of  lime  and  potass, 
and  is  corroborated  by  there  being  no  gas  but  ammonia  dis- 
engaged, and  no  boron  deposited  during  the  decomposition  : 

(N3  B2  K3  and  9  H  O  =  2  B  Os  +  3  K  O  and  3  N  H3). 

However,  it  may  be  that  there  are  only  two  atoms  of  potas- 
sium, since  the  compound  can  only  be  obtained  at  such  a  tem- 
perature as  would  volatilize  potassium ;  from  which  it  would 
appear  that  potassium  was  set  free  during  its  formation ;  and 
moreover,  during  the  decomposition  by  hydrate  of  potass  or 
lime,  a  new  compound  is  formed  which  may' possibly  contain 
the  original  compound  with  oxygen,  being  somewhat  analo- 
gous to  cyanate  of  potass,  in  which  case  the  oxygen,  set  free 
from  the  hydrogen  which  has  to  form  ammonia,  might  be 
theoretically  disposed  of  without  the  supposition  that  there 
are  three  atoms  of  potassium  (N3  B2  K2  and  9  H  O  =  2  B  03 
+  2  KO  and  3  N  H3  and  O,  which  would  go  to  undecomposed 
substance);  but  at  the  same  time,  this  new  compound  may 
contain  oxygen  and  have  derived  it,  not  from  the  decomposed 
water,  but  from  the  air  in  the  vessel.  It  is  formed  when  the 
"boronitruret  of  potassium"  is  fused  with  potass,  and  an  excess 
of  acid  added  to  the  solution  of  the  result ;  at  first  it  appears 
as  a  milkiness  in  the  liquid,  but  by  continued  ebullition,  col- 
lects into  a  distinct  precipitate,which  when  dry  is  a  remarkably 
coherent  thready  solid. 

When  heated  before  the  blowpipe  it  gives  a  strong  green 
flame  without  melting ;  it  yields  ammonia  abundantly  with  hy- 
drate of  lime  and  carbonate  of  potass  (a  mixture  which  I  used 
instead  of  hydrate  of  potass),  and  in  other  respects  behaves 
like  the  "  boronitruret  of  potassium,"  excepting  that  it  yields 
no  phosphorescence,  and  when  slowly  oxidized  forms  a  very 
fusible  bead,  which  during  its  oxidation  throws  out  small  ve- 
sicles owing  to  the  escape  of  gas.     The  substance  operated 

Phil.  Mae.  S.  3.  Vol.  2 1 .  No.  1 38.  Oct.  184-2.        T       * 


274  Mr.  W.  H.  Balmain  on  the  Formation  of  Compounds  of 

upon  was  obtained  chiefly  from  an  incomplete  analysis  of  the 
"  boronitruret  of  potassium,"  by  heating  it  with  hydrate  of 
lime;  the  result  being  diffused  through  water,  a  stream  of 
carbonic  acid  passed  through  it,  and  the  whole  boiled,  borate 
of  potass  was  in  solution  and  carbonate  of  lime  precipitated, 
which,  being  acted  upon  by  muriatic  acid,  yielded  an  imper- 
fectly transparent  liquid,  and  from  this  the  thready  substance 
was  deposited  on  long-continued  ebullition. 

All  attempts  to  decompose  the  "  boronitruret  of  potassium," 
so  as  to  isolate  the  theoretical  "  boride  of  nitrogen,"  have 
hitherto  been  unsuccessful ;  each  experiment  adding  its  testi- 
mony to  the  remarkable  stability  of  the  compound.  It  can- 
not be  done  by  means  of  oxidizing  agents,  for  both  the  potas- 
sium and  the  boron  take  oxygen  at  the  same  time,  and  either 
boracic  acid  and  potass  are  formed,  or  else  the  thready  substance 
alluded  to  above,  as  appeared  to  be  the  case  when  peroxide 
of  manganese  with  boracic  or  sulphuric  acid  was  used  as  the 
oxidizing  agent,  since,  after  diluting  and  acting  upon  the  re- 
sidue with  a  solution  of  oxalic  and  sulphuric  acids  to  remove 
boracic  acid  and  any  remaining  peroxide  of  manganese,  a 
white  solid  was  left  which  had  the  same  appearance  and,  before 
the  blowpipe,  the  same  characters  as  that  substance. 

Finding  that  cyanogen  passed  over  a  mixture  of  boracic 
acid  and  charcoal  heated  to  redness  gave  me  no  result,  I  en- 
deavoured, as  a  last  resource,  to  obtain  compounds  of  "  boride 
of  nitrogen"  with  the  common  metals  by  heating  their  cy- 
anides with  boracic  acid,  fully  expecting  that  these  cyanides 
would  decompose  at  too  low  a  temperature  for  the  deoxidation 
of  the  boron  to  take  place,  and  I  was  agreeably  surprised 
when  upon  trial  it  appeared  that  the  cyanide  of  copper 
heated  with  boracic  acid  gave  a  result,  which,  after  being 
washed,  yielded  ammonia  when  heated  with  a  mixture  of  hy- 
drate of  lime  and  carbonate  of  potass;  and  cyanide  of  lead,  a 
result  which  not  only  yielded  ammonia,  but  produced  a  phos- 
phorescence before  the  blowpipe  which  differed  from  that  of 
the  "  boronitruret  of  potassium  "  only  in  its  colour,  which 
was  more  yellow  and  less  green. 

Both  of  these  results  were  so  impure,  owing  to  the  presence 
of  oxides  in  the  cyanides,  that  their  characters  could  not  be 
taken  as  those  of  the  compounds  of  the  metals  with  "  boride 
of  nitrogen,"  and  they  were  only  valuable  as  proving  the 
possibility  of  making  those  compounds  by  such  a  process. 
The  copper  result  gave  a  very  fine  green  flame  before  the 
blowpipe,  but  would  not  phosphoresce  ;  and  after  the  metallic 
copper  had  been  removed  by  nitric  acid  a  substance  remained 
which  appeared  more  like  the  "thready  compound"  supposed 


Boron  and  Silicon  with  Nitrogen.  275 

to  contain  oxygen,  than  the  "  boronitruret  of  potassium." 
Cyanide  of  mercury  heated  with  boracic  acid  gave  cyanogen 
abundantly,  which  burned  with  a  tinge  of  green  in  its  flame ; 
and  at  the  same  time  a  small  quantity  of  white  crystalline 
solid  sublimed,  which  may  prove  to  be  a  compound  of  mer- 
cury with  the  M  boride  of  nitrogen,"  and  being  such,  if  it  could 
be  obtained  in  larger  quantity,  might  probably  be  a  means  of 
isolating  the  much-wished  for  "  boride  of  nitrogen."  It  was 
soluble  in  water,  giving  it  a  bitter  taste ;  and  the  solution  gave 
no  precipitate  with  a  salt  of  iron,  but  an  abundant  white  with 
protochloride  of  tin :  with  iodide  of  potassium  none,  with 
acetate  of  lead  none,  with  nitrate  of  silver  a  slight  precipitate, 
which  was  insoluble  in  excess  of  acid.  It  was  likewise  soluble 
in  alcohol,  but  the  solution  did  not  burn  with  a  green  flame. 
Boiled  with  a  solution  of  carbonate  of  potass  it  yielded  am- 
monia, and  it  communicated  a  green  colour  to  flame,  passing 
off  rapidly  in  vapour,  and  giving  a  greenish  blue  colour  to  the 
flame  in  its  immediate  neighbourhood. 

A  mixture  of  one  part  of  anhydrous  boracic  acid  with  two 
and  a  half  parts  of  cyanide  of  zinc,  heated  to  whiteness  in  a 
lined  crucible  (covered  and  well  luted),  yielded  a  white  solid 
similar  in  appearance  to  that  obtained  by  heating  a  mixture  of 
boracic  acid  and  cyanide  of  potassium.  It  gave  ammonia  abun- 
dantly when  heated  with  a  mixture  of  hydrate  of  lime  and  car- 
bonate of  potass,  and  was  insoluble  (with  and  without  heat)  in 
water,  sulphuric  acid,  hydrochloric  acid,  nitric  acid,  solution  of 
chlorine,  solution  of  potass  and  ammonia.  It  is  not  decomposed 
by  chlorine  at  ajicll  red  heat,  nor  by  corrosive  sublimate,  nor 
by  potassium  or  sodium.     Before  the  blowpipe  it  is  infusible, 
but  in  the  oxidizing  flame  communicates  a  green  colour,  and 
when  at  the  outer  edge  emits  a  very  brilliant  bluish  phos- 
phorescence, which  appearance  it  also  produces  when  simply 
dropped  into  the  flame  of  a  spirit-lamp.     Thrown  on  fused 
chlorate  of  potass  it  deflagrates  with  a  faint  blue  light.     These 
characters  are  exactly  such  as  we  should  expect  to  find  in  a 
compound  of  zinc  with  "  boride  of  nitrogen  "  analogous  to  the 
compound  of  potassium.     It  appeared  to  be  in  a  state  of 
purity,  and  is  more  readily  obtained  than  the  potassium  com- 
pound, since  the  preparation  of  a  pure  cyanide  of  zinc  is  ac- 
complished with  greater  facility  than  that  of  cyanide  of  potas- 
sium.    Besides  its  interest  in  being  distinctly  a  second  com- 
pound of  the  kind,  and  the  remarkable  beauty  of  its  phospho- 
rescence before  the  blowpipe,  it  is  of  importance  as  affording 
a  means  of  preparing  the  analogous  compound  of  other  metals 
by  heating  it  with  their  chlorides.     Heated  to  whiteness  in  a 
lined  crucible  in  the  proportion  of  one  atom  of  itself  (taking 

T2 


276      Compounds  of  Boron  and  Silicon  with  Nitrogen. 

its  composition  to  be  Zn2  N3  B2)  to  two  atoms  of  the  chloride, 
it  yielded,  with  chloride  of  lead,  a  white  solid  which  gave 
ammonia  abundantly  when  heated  with  a  mixture  of  hydrate 
of  lime  and  carbonate  of  potass,  and  phosphoresced  with 
a  yellowish  green  light  at  the  point  of  the  blowpipe  flame ; 
water  boiled  with  it  afterwards  gave  no  precipitate  with  nitrate 
of  silver,  and  when  it  was  heated  before  the  blowpipe  with 
soda  upon  charcoal,  it  gave  a  distinct  button  of  lead  and  only 
a  minute  trace  of  zinc ;  with  chloride  of  copper,  a  result 
similar  to  that  obtained  by  heating  together  cyanide  of  copper 
and  boracic  acid. 

With  chloride  of  silver,  a  result  which  resembled  the  lead 
compound,  and  phosphoresced  brilliantly  with  a  yellowish - 
green  light.  It  was  not  decomposed  by  hydrochloric  acid, 
nor  by  chlorine  at  a  low  red  heat,  nor  by  corrosive  sublimate, 
and  indeed  appeared  under  all  circumstances  as  stable  as  the 
rest,  remaining  unaltered  even  when  heated  in  a  tube  with 
sodium  and  potassium.  With  the  chlorides  of  sodium,  ba- 
rium, strontium,  calcium  and  manganese,  results  which  ap- 
peared to  be  "  boronitrurets"  of  those  metals ;  but  in  these 
cases  the  experiments  were  made  with  small  quantities,  solely 
with  a  hope  of  finding  a  soluble  compound  ;  and  as  not  one 
of  them  would  yield  ammonia  when  boiled  in  water  with  hy- 
drate of  lime  and  carbonate  of  potass,  and  as  water  after 
ebullition  in  contact  with  them  gave  no  precipitate  with  so- 
lutions of  the  oxides  of  lead,  silver,  copper,  iron,  &c,  I  con- 
cluded that  I  had  not  been  successful  in  my  search. 

Six  parts  of  silica  heated  to  whiteness  with  thirteen  parts 
of  cyanide  of  potassium  gave  a  brittle  porous  vitreous  solid, 
which,  after  being  well  washed,  yielded  ammonia  abundantly 
when  heated  with  hydrate  of  lime  and  carbonate  of  potass. 
Heated  with  fused  potass  it  yielded  ammonia  abundantly. 
After  ebullition  with  sulphuric  acid  it  still  yielded  ammonia 
when  heated  with  hydrate  of  lime  and  carbonate  of  potass. 
In  the  deoxidizing  flame  it  fused  tranquilly,  and  in  the  oxidi- 
zing with  escape  of  gas.  With  carbonate  of  soda  it  gave  a 
red  bead  in  the  deoxidizing  flame,  the  colour  of  which  disap- 
peared in  the  oxidizing  flame,  and  could  not  be  recovered. 
After  being  heated  with  nitrate  of  ammonia  and  well  washed, 
it  yielded  ammonia  with  hydrate  of  lime  and  carbonate  of 
potass,  more  abundantly  than  before.  From  this  it  appears 
that  a  compound  of  silicon  and  nitrogen  with  potassium  ana- 
logous to  the  boron  compound  had  been  formed,  and  that  it 
is  nearly  as  stable  as  that  substance ;  but  as  I  had  no  means 
of  separating  the  compound  from  impurity,  nothing  further 
can  be  said  at  present. 


Prof.  Miller  on  Tourmaline,  Dioptase,  and  Anatase.    277 

From  the  above  results,  and  from  a  few  doubtful  experiments 
which  have  not  been  mentioned,  I  conclude  that  compounds 
of  nitrogen  with  boron  and  silicon  had  been  formed,  and  that 
their  chemical  relations  are  similar  to  those  of  cyanogen; 
and  I  have  no  doubt  that  analogous  compounds  of  alumi- 
nium, glucinium,  &c.  may  also  be  formed ;  moreover,  I  have 
hopes  that  the  fundamental  principles  of  the  science  of  che- 
mistry may  be  further  elucidated  by  some  of  these  compounds 
proving  to  be,  if  not  some  of  our  "  elements,"  at  least  of  a 
nature  closely  analogous.  We  are  not  to  suppose  that  the 
affinity  of  nitrogen  for  the  other  elements  is  weak  because  it 
will  not  unite  with  them  directly  as  by  a  process  of  combus- 
tion, especially  as  the  compounds  of  nitrogen  at  present  known 
are  not  formed  directly,  and  in  many  the  affinity  has  proved 
stronger  than  was  at  first  supposed.  This  compound  of  boron 
and  nitrogen  resists  all  agents  but  oxygen,  and  analogous 
compounds  with  bases  not  so  easily  oxidized  might  appear  to 
us  elementary,  and  a  glance  over  the  relative  constitution  of 
our  earth  and  atmosphere  may  in  some  measure  justify  us  in 
expecting  to  find  nitrogen  abundantly  in  the  mineral  king- 
dom; and  this  point  decided  positively,  may  throw  much  light 
upon  the  connexion  between  organic  and  inorganic  chemistry. 
My  opinion  is  founded  upon  a  careful  review  of  many  well- 
known  facts,  and  is  not  solely  dependent  upon  these  recent 
experiments  for  its  support,  but,  on  the  contrary,  they  have 
been  instituted  to  discover  evidence,  and  I  hope  that  while 
my  labours  are  still  continued  others  will  be  induced  to  join 
in  the  same  pursuit. 

William  H.  Balmain. 

XL VI I.    On  the  Optical  Constants  of  Tourmaline,  Dioptase 
and  Anatase.   By  W.  H.  Miller,  M.A.,  F.R.S.,  Professor 

of  Mineralogy  in  the  University  of Cambridge* . 

r|^HE  values  of  the  optical  constants  of  Tourmaline  were 
deduced  from  observations  made  with  a  prism  cut  out  of 
a  colourless  crystal  in  the  possession  of  Mr.  Brooke,  which, 
though  not  sufficiently  perfect  to  show  the  dark  lines  in  the 
spectrum,  exhibits  the  bright  line  in  the  flame  of  alcohol  very 
distinctly.  For  this  light  the  index  of  refraction  of  the  ordi- 
nary ray  out  of  air  into  the  crystal  is  1*6366;  in  an  extraor- 
dinary ray  perpendicular  to  the  axis  of  the  rhombohedron  the 
velocity  of  light  in  air  divided  by  its  velocity  within  the  cry- 
stal is  T6193.  A  slice  of  the  same  crystal  bounded  by  planes 
perpendicular  to  the  axis,  0*68  inch  thick, being  placed  in  a  po- 
*  Communicated  by  the  Author. 


278  Notices  of  the  Labours  of  Continental  Chemists:  Cerium,  ^c. 

larizing  apparatus,  the  diameter  in  air  of  the  darkest  part  of 
the  first  ring  is  about  7°  30'.  When  this  mineral  is  coloured, 
as  is  usually  the  case,  the  optical  constant  belonging  to  the 
extraordinary  ray  cannot  be  determined,  on  account  of  the 
absorption  of  the  light  polarized  in  the  plane  of  the  axis. 

In  Dioptase,  according  to  observations  made  with  a  very 
perfect  and  transparent  crystal,  for  which  I  am  indebted  to 
Mr.  Heuland,  for  the  brightest  part  of  the  solar  spectrum  the 
index  of  refraction  of  the  ordinary  ray  is  1*667;  in  an  extra- 
ordinary ray  perpendicular  to  the  axis  the  velocity  of  light  in 
air  divided  by  its  velocity  within  the  crystal  is  1*723. 

In  Anatase,  for  the  brightest  part  of  the  solar  spectrum,  the 
index  of  refraction  of  the  ordinary  ray  is  2*554;  in  an  ex- 
traordinary ray  perpendicular  to  the  axis,  the  velocity  of 
light  in  air  divided  by  its  velocity  within  the  crystal  is  2*493. 

St.  John's  College,  Sept.  9,  1842.  W.  H.  MlLLER. 


XLVIII.  Notices  of  the  Results  of  the  Labours  of  Continental 
Chemists.     By  Messrs.  W.  Francis  and  H.  Croft. 

[Continued  from  p.  21.] 

On  Cerium  and  some  of  its  Salts,  and  on  Didymium. 

\  N  examination  respecting  the  true  atomic  weight  of  cerium 
■^*-  has  been  made  by  M.  A.  Beringer  in  the  laboratory  of 
Professor  Wohler ;  new  experiments  on  this  subject  were  ne- 
cessary on  account  of  the  discovery  of  lanthanium.  It  will 
however  be  useless  to  insert  this  treatise  in  these  reports,  inas- 
much as  a  notice  has  appeared  in  PoggendorfF's  Annals,  vol. 
lvi.  p.  503,  from  which  we  learn  that  Mosander  has  discovered 
a  third  metal  mixed  with  cerium  and  lanthanium,  which  he 
calls  Didymium.  It  is  scarcely  possible  to  separate  the  oxide 
of  this  metal;  Mosander,  although  he  has  known  this  body  one 
year  and  a  half,  has  as  yet  been  unable  to  isolate  it  in  a  pure 
form.  Oxide  of  didymium  causes  the  brown  colour  of  the 
so-called  oxide  of  cerium,  and  also  the  rose  or  amethyst 
tinge  of  some  salts  of  yttria.  The  perfectly  pure  oxides  of 
lanthanium  and  cerium  are  probably  quite  colourless.  In 
the  usual  mode  of  preparing  oxide  of  lanthanium  by  means 
of  dilute  nitric  acid,  the  whole  of  it  is  never  extracted,  but 
part  remains  with  the  oxide  of  cerium.  Mosander  is  engaged 
with  the  examination  of  the  three  bodies,  and  from  him  we 
may  expect  a  full  description.  Beringer  has  examined  metallic 
cerium  (impure),  the  double  sulphates,  and  some  other  salts. 
— (Antialen  der  Chemie  und  Pharmacie,  vol.  xlii.  p.  134.) 


Atomic  Weight  of  Chlorine, — Hyposulphites.         279 

On  the  Atomic  Weight  of  Chlorine,  Zinc,  $c. 

Laurent  has  made  some  experiments  on  the  atomic  weight 
of  chlorine;  the  assumption  of  Berzelius's  number  agrees 
completely  with  the  analyses,  while  considerable  differences 
are  visible  if  the  atom  be  considered  as  a  multiple  of  that  of 
hydrogen.  Marignac  determines  the  atomic  weight  by  pass- 
ing hydrochloric  acid  gas  over  heated  oxide  of  copper ;  he 
finds  225*013,  or  thirty-six  times  that  of  hydrogen.  From 
this  he  reckons  the  atomic  weight  of  silver  1374*0,  and  of 
potassium  498*5.  Jacquelain  finds  the  atomic  weight  of  zinc 
to  be  414. — {Comptes  Rendus,  Mar.  1842,  p.  456;  Ibid, 
Avril  1842,  p.  570;  Ibid.  Mai  1842,  p.  636.) 

On  the  Hyposulphites. 
Rammelsberg  has  published  an  examination  of  this  class  of 

salts :  the  deliquescent  potash  salt  has  the  formula  3  KS  +  H. 
The  soda  salt  contains  5  atoms  of  water,  that  with  ammonia 
has  the  same  composition  as  the  potash  salt.  The  baryta  salt 
contains  1  atom  of  water,  that  with  strontia  5  atoms,  with 
lime  and  magnesia  6  atoms.     A  deliquescent  double  salt  of 

magnesia  and  potassa  has  the  formula  K  S  +  Mg  S  +  6  aq. 
Hyposulphite  of  manganese  decomposes  on  evaporation  into 
sulphur  and  sulphate,  the  zinc  salt  the  same ;  a  compound  of 
the  zinc  salt  may  be  obtained  by  adding  ammonia  in  excess 
to  a  solution  of  the  hyposulphite  and  precipitating  the  salt  by 

alcohol ;  it  is  Zn  S  +  N  H3.  The  nickel  and  cobalt  salts  have 
the  same  constitution  as  the  magnesia  compound ;  the  nickel 

salt  combines  with  ammonia,  and  gives  (Ni  S  +  6  H)  +  2  N  H3. 
Hyposulphite  of  lead  dissolves  in  solutions  of  alkaline  and 
earthy  hyposulphites,  and  forms  double  salts  which  are  easily 
decomposed.     Their  solutions  must  not  be  heated,  for  then 
sulphuret  of  lead  is  formed ;  they  are  partly  decomposed  by 

water.     The  potassa  salt  is  Pb  S  +  2  K  S  +  2  aq,  the  ammonia 

salt  Pb  S_+  2  N  H4  O  S  +  3  aq.  The  soda  salt  has  been  de- 
scribed by  Lenz  {vide  the  last  Report) .  Salts  may  also  be  form- 
ed with  baryta  and  strontia;  the  lime  salt  is  Pb  S  +  2CaS  +  4aq. 
Hyposulphite  of  oxide  of  mercury  cannot  be  obtained ;  but  by 
digesting  the  oxide  with  solutions  of  hyposulphites  double  salts 
are  formed ;  the  ammonia  and  potassa  salts  crystallize,  the 

former  is  HgS  +  4 N  H4OS  +  2aq ;  the  formula  of  the  potassa 


280        Notices  of  the  Labours  of  Continental  Chemists, 

salt  is  rather  uncertain ;  the  soda  salt  does  not  crystallize,  nor 
do  the  compounds  of  the  earthy  hyposulphites. 

A  solution  of  the  potassa  double  salt  added  to  sulphate  of 
copper  causes  a  brownish-red  precipitate,  which  has  the  same 

formula  as  the  potassa  salt,  viz.  3  Hg  S  +  5  Cu  S. 

On  adding  hyposulphite  of  potassa  to  sulphate  of  copper  a 

yellow  precipitate  is  produced,  the  formula  of  which  is  K  S 

-f  Cu  £H-  2  aq ;  it  dissolves  in  excess  of  alkaline  hyposulphite 
and  alcohol  precipitates  from  this  solution  another  crystalli- 

zable  salt,  3  K  S  +  Cu  S  +  3  aq. 

A  soda  salt  similar  to  the  first  of  these  has  been  described 

by  Lenz,  it  dissolves  in  excess  of  Na  S,  and  gives  3  NaS 

+  Cu  S  +  2  aq. 

Rammelsberg  has  also  examined  the  products  of  the  de- 
structive distillation  of  the  hyposulphites ;  he  finds  that  sul- 
phurets,  sulphates,  and  sometimes  sulphites  are  formed. — 
(Poggendorff's  Annalen,  vol.  xlvi.  p.  295.) 
On  the  Sulphocyanurets. 

Meitzendorff  has  made  an  extensive  series  of  experiments 
on  these  salts,  under  the  direction  of  Rammelsberg.  The 
acid  was  obtained  by  distilling  the  potassium  salt  with  tar- 
taric acid.  We  will  here  only  mention  the  chief  peculiarities 
of  the  salts,  and  refer  the  reader  for  fuller  information  to  the 
long  paper  itself.  The  ammonium  and  sodium  salts  are  an- 
hydrous, Na,  Cy  S2  and  N  H4,  Cy  S2.  The  barium,  stron- 
tium, magnesium  and  calcium  salts  are  crystallized  and  deli- 
quescent, Ba,  Cy  S2  +  2  aq,  Sr,  Cy  S2+  3  aq,  Ca,  Cy  S2  +  3aq, 
and  Mg,  Cy  S2  +  4  aq.  The  solution  of  the  aluminum  salt  is 
decomposed  by  evaporation  into  an  insoluble  basic  and  a  so- 
luble neutral  salt.  The  crystallized  manganese  salt  contains 
3  atoms  of  water;  the  zinc  salt  is  anhydrous,  it  combines  with 
ammonia,  forming  a  salt  which  crystallizes  in  beautiful  cry- 
stals, it  is  Zn,  Cy  S2  +  N  H3.    Cobalt  salt  does  not  crystallize, 

it  is  2  Co,  Cy  S2+  H ;  it  forms  two  compounds  with  ammonia. 
The  nickel  salt  has  the  same  composition,  and  the  anhydrous 
salt  forms  with  two  atoms  of  ammonia  a  crystallizable  salt. 
The  crystallized  cadmium  salt  is  anhydrous,  combines  with 
one  atom   of  ammonia.     There    are  two  salts  of  bismuth, 

Bi,  Cy  S2  and  Bi,  Cy  S2  +  4  Bi  +  2  aq.  The  rf/sulphocyanuret 
of  copper  is  anhydrous,  but  retains  a  little  moisture  with  great 


On  the  Sulphates  of  Alumina  and  of  Chromium.       281 

obstinacy.  The  sulphocyanuret  may  be  obtained  by  using 
very  concentrated  solutions  of  the  sulphate  of  copper  and  the 
sulphocyanuret  of  potassium ;  it  is  precipitated  as  a  black  pow- 
der, and  is  anhydrous.  Its  decomposition  with  water,  which 
has  been  studied  by  Claus,  is  very  curious  ;  it  changes  in  water 
into  the  white  disulphocyanuret ;  it  appears  that  at  the  same 
time  hydrosulphocyanic,  hydrocyanic  and  sulphuric  acids  are 
formed  (the  iron  salt  appears  to  be  similar  in  properties).  The 
sulphocyanuret  of  copper  forms  a  crystallizable  salt  with,  one 
atom  of  ammonia. — (PoggendorfPs  Annale?i,  vol.  xlvi.  p.  63.) 

On  the  Sulphates  of  Alumina  and  of  Chromium. 

In  the  45th  volume  of  PoggendorfPs  Annals,  page  99, 
Hertwig  published  apaper  on  the  proportions  in  which  alumino- 
sulphate  of  potassa  (alum)  can  combine  with  water;  he  found 
that  when  large  crystals  of  common  alum  are  allowed  to  lie 
for  some  time  in  concentrated  sulphuric  acid  they  are  not 
dissolved  but  dispersed  through  the  acid,  forming  a  gelatinous 
mass;  water  throws  down  a  crystalline  powder,  which  on  being 
pressed  between  bibulous  paper  and  recrystallized  from  a  hot 
solution,  gives  a  salt  in  the  form  of  regular  octohedrons,  which 
contains  only  14  atoms  of  water,  whereas  the  common  alum 
contains  24.  In  the  same  volume,  page  331,  there  is  a  paper 
by  Heintz  who  has  not  been  able  by  these  means  to  procure 

anything  but  common  alum  (Al  S3,  K  S  +  24  aq).  By  the 
united  action  of  heat  and  sulphuric  acid  Hertwig  obtained  an- 
other compound,  Al  S3  +  K  S  ■+•  3  aq,  which  is  a  very  insoluble 
salt,  and  becomes  still  more  so  when  strongly  heated;  it  must 
therefore  be  an  isomeric  modification  of  anhydrous  alum. 
Common  alum  when  kept  for  a  length  of  time  at  a  tempera- 
ture of  100°  C.  loses  10  atoms  of  water,  but  this  salt  differs 
considerably  in  its  properties  from  that  with  14  atoms  of 
water  mentioned  above.  By  a  heat  of  120°  to  160°  a  com- 
pound of  5  atoms  is  obtained,  at  200°  with  1  atom.  By 
somewhat  similar  means  to  those  employed  by  Hertwig,  Heintz 

has  obtained  two  salts  with  oxide  of  iron,  Fe  S3,  K  S  +  3  aq 

and  Fe  S3,  K  S  +  2  aq.     The  true  colour  of  the  iron  alum 

appears  to  be  violet,  when  mixed  with  common  alum  it  is 
quite  white.  In  vol.  lvi.  of  the  same  Journal,  p.  95,  Hertwig 
has  described  some  modifications  of  the  chrome  alum.  If  a 
very  concentrated  solution  of  the  green  double  sulphate  be 
evaporated  with  concentrated  sulphuric  acid  as  long  as  water 
is  driven  off,  a  green  anhydrous  chromosulphate  of  potassa  is 


282        Notices  of  the  Labours  of  Continental  Chemists. 

precipitated,  which  is  insoluble  in  boiling  or  cold  water,  hydro- 
chloric, sulphuric  and  nitric  acids ;  it  is  not  altered  by  am- 
monia, but  it  is  decomposed  by  boiling  with  caustic  potassa ; 

formula,  Cr  S3,  K  S.  It  is  easily  decomposed  by  heat.  It  is 
evident  therefore  that  the  chrome  alum  can  exist  in  three  dif- 
ferent isomeric  modifications.  When  chrome  alum  is  heated  at 
200°  C.  as  long  as  water  is  driven  off,  a  "  difficultly  soluble" 
green  modification  is  formed  ;  it  contains  2  atoms  of  water ;  it 
is  insoluble  in  cold  water,  and  also  in  sulphuric  and  hydro- 
chloric acids,  but  it  is  dissolved  by  continued  boiling  with 
water ;  decomposition  is  also  effected  by  boiling  ammonia. 
When  heated  to  300°-400°  it  passes  into  the  "  insoluble" 
modification,  its  dark  green  colour  changes  to  light  green,  and 
it  has  lost  all  its  water.  This  anhydrous  salt  differs  from  that 
obtained  with  sulphuric  acid,  inasmuch  as  by  long  boiling  with 
water,  sulphate  of  potassa  is  dissolved  and  insoluble  sulphate 
of  chromium  remains  behind. 

In  vol.  xliii.  of  the  same  Journal,  p.  513,  Schrotter  has  de- 
scribed some  sulphates  of  chromium.  Cr  S2  is  obtained  by 
adding  as  much  hydrated  oxide  of  chromium  to  sulphuric 
acid  as  it  can  take  up  when  kept  boiling  for  a  long  time ;  it  is 
not  crystallizable,  and  forms  a  green  mass  on  evaporation  ;  on 
the  addition  of  water  a  light  green  powder  separates,  which  is 

Cr3  S2  +  1 2  aq.  If  a  solution  of  the  first  salt  be  heated  with 
excess  of  sulphuric  acid  the  green  colour  disappears  and  a 
peach  red  precipitate  is  formed,  which  is  not  soluble  in  water, 
and  is  not  decomposed  by  acids  or  ammonia,  but  easily  by 
caustic  potassa  or  soda.  A  solution  of  this  salt  may  be 
obtained  by  dissolving  eight  parts  of  oxide  in  nine  parts  of 
English  sulphuric  acid;  alcohol  does  not  precipitate  the 
fresh  solution  ;  if  it  be  allowed  to  stand  several  weeks  it 
forms  a  greenish  blue  crystalline  mass, which  dissolved  in  water 
forms  a  dark  blue  (by  transmitted  light  ruby  red)  solution. 
Out  of  this  alcohol  precipitates  a  light  violet-coloured  crystal- 
line salt,  Cr  S3+  15  aq,  which  is  easily  soluble  in  water,  be- 
comes green  when  heated  to  100°,  and  loses  10  atoms  of  water. 
For  preparing  the  chrome  alum,  Schrotter  proposes  to  pass 
sulphurous  acid  into  a  solution  of  one  atom  of  bichromate  of 
potassa  and  one  atom  of  sulphuric  acid,  as  long  as  it  is  ab- 
sorbed, the  mixture  being  kept  cool.  He  has  also  prepared 
the  ammonia  and  soda  chrome  alum ;  they  both  contain  24 
atoms  of  water.  [The  ammonia  compound  was  prepared  by 
Mr.  Warington  several  years  ago  {vide  Turner's  Chemistry).; 


On  some  Chromates.  283 

it  has  also  been  examined  by  Mitscherlich ;  vide  Lehrbuch, 
vol.  ii.  part  2.] 

Hydrated  oxide  of  chromium  dried  at  100°  contains  six 
atoms  of  water.  Schrbtter  also  states  that  the  green  modifi- 
cation of  chrome  alum  when  in  solution  passes  gradually  into 
the  blue  one.  [This- statement  I  can  fully  confirm  from  my 
own  old  observations.  This  change  of  the  green  into  the  blue 
oxide  accounts  for  Warington's  preparation  of  the  double 
oxalates  of  chromium  and  potassa  by  means  of  green  oxide  of 
chromium*,  although  from  the  mode  of  preparation  it  is  evi- 
dent that  the  blue  oxide  is  the  base  in  the  black  and  red  ox- 
alates.— H.  C] 

On  some  Chromates. 

Kopp  has  examined  several  of  these  salts,  principally  with 
a  view  to  determining  their  specific  gravities  and  atomic 
volumes.  The  chromates  of  zinc  and  copper  may  be  obtained 
by  dissolving  the  oxides  or  carbonates  in  dilute  chromic  acid 
(prepared  by  Fritzsche's  method),  or  by  digesting  chromate 
of  baryta  with  the  sulphates  [several  salts  of  the  magnesian 
class  were  prepared  some  years  since  in  this  manner  by  Mr. 
Play  fair,  but  no  account  of  them  has  been  published].  The 
salts  of  copper  and  zinc  have  the  same  form  and  composition 
as  the  sulphates  of  those  oxides ;  the  soda  salt  is  similar  to  the 
sulphate,  it  deliquesces.  By  evaporating  its  solution  at  30°  C. 
anhydrous  chromate  may  be  obtained.  The  chromates  of  am- 
monia and  magnesia  are  precisely  similar  to  the  corresponding 
sulphates. — (Annalen  der  Chemie,  Sfc,  vol.  xlii.  p.  97.) 

Benschhas  published  a  notice  on  some  basic  chromates  ob- 
tained by  pouring  a  solution  of  chromate  of  potassa  into  boil- 
ing neutral  metallic  solutions.  These  precipitates  must  be 
washed  with  hot  water,  or  else  they  retain  some  potassa ;  by 
boiling  they  appear  to  be  decomposed.  None  of  them  have 
been  properly  examined  as  yet ;  the  manganese  salt  is  black, 

its  formula  is  Mn2  Cr  +  2  aq.  When  heated  red-hot  the 
water  and  some  oxygen  are  driven  off. — (PoggendorfFs  An- 
nalen,  vol.  1.  p.  97.) 

[The  same  salt  appears  to  have  been  formed  by  Mr.  Wa- 
rington  (Reports  of  the  Chem.  Soc,  part  3),  who  has  obtained 
the  same  formula.  Salts  of  protoxide  of  manganese  are  white 
or  pinkish ;  the  salts  of  chromic  acid  are  seldom  very  dark- 
coloured,  and  it  appears  rather  anomalous  that  this  basic  salt 
should  be  black.  It  might  be  Cr  02  +  Mn2  03+  2aq;  when 
treated  with  hydrochloric  acid  the  sesquioxide  of  manganese 
would  cause  evolution  of  chlorine,  and  a  brown  chloride  of 
chromium  might  be  produced,  which  by  the  addition  of  alco- 
*  See  p.  201  of  the  present  volume.— Edit. 


284        Notices  of  the  Labours  of  Continental  Chemists. 

hoi  would  be  reduced  to  the  green  chloride ;  this  agrees  with 
Warington's  experiments. — H.  C] 

On  Glucinium  and  its  Compounds. 

Awdejew  has  made  a  series  of  experiments  on  the  salts  of 
glucina,  under  the  direction  of  H.  Rose.  Great  care  was  used 
in  the  preparation  and  analysis  of  the  chloride  of  glucinium. 
It  was  found  to  contain  87*54  per  cent,  of  chlorine,  whereas 
it  has  been  supposed  to  contain  only  66*70.  When  dissolved 
in  water  it  forms  hydrochlorate  of  glucina  ;  on  evaporating  the 
solution  a  crystalline  mass  is  obtained  which  has  the  composi- 
tion GC1  +  4  aq.  [Awdejew  supposes  the  oxide  to  contain  one 
atom  of  oxygen.]  The  atomic  weight  of  the  oxide  was  de- 
termined from  the  analysis  of  the  neutral  sulphate,  which  is 
obtained  by  dissolving  the  carbonate  in  excess  of  sulphuric 
acid  and  separating  by  alcohol ;  the  salt  is  precipitated  and 

may  be  dissolved  and  recrystallized  ;  its  formula  is  G  S  +  4  aq. 
The  atomic  weight  of  glucina  is,  according  to  these  analyses, 
158*084,  and  that  of  the  metal  58*084.  A  double  sulphate  of 
glucina  and  potassa  may  be  obtained  by  gently  evaporating 
a  mixture  of  equal  atoms  of  the  two  sulphates ;  it  is  decom- 
posed by  boiling,  slowly  soluble  in  cold  water.     Its  formula  is 

KS  +  GS  +  2aq.  Itmightbe  3  K  S  +  G  S3,  but  KS+J}  S3 
cannot  be  formed.  The  double  fluoride  of  glucinium  and 
potassium  was  also  analysed ;  it  is  K  F  +  G  F ;  it  is  anhydrous, 
difficultly  soluble.  There  are  three  basic  sulphates  which 
have  been  described  and  analysed  by  Berzelius  (Lehrbuch,  iv) . 

These  formulas,  according  to  the  new  equivalent,  are  G3  S,  G2  S 

and  G6  S  +  3  aq.  At  the  end  of  his  treatise  Awdejew  consi- 
ders how  the  formulas  of  minerals  containing  glucina  are  af- 
fected by  this  change  in  the  atomic  weight.     Chrysoberyll 

becomes  G  Al;  phenakite  G3  Si;      beryll  GPSi  +  Al  Si; 

euklas  2  G3Si  +A12  Si;  leucophane  G3  Si+Ca3  Si2  +  Na  F 
— (Pogg.  Ann.,  vol.  lvi.  p.  101.) 

In  vol.  1.  of  the  same  Journal  Count  Schaffgotsch  published 
some  experiments  on  glucina.    He  analysed  the  hydrate,  and 

gave  as  its  formula  G-f8aq;  according  to  the  new  atomic 

weight  G3  +  4  aq  would  agree  best  with  the  analysis ;  the 
oxide  is  dissolved  by  concentrated  caustic  potassa,  and  is  not 
precipitated  by  boiling,  unless  the  solution  be  diluted,  when 
the  whole  is  thrown  down.    By  boiling  the  solution  of  glucina 


Action  of  water  on  Sulpkurets  and  haloid  Salts.  285 
in  carbonate  of  ammonia  a  granular  salt  is  precipitated,  for 
which  Schaffgotsch  proposes  the  formula  2  G  C3  H6+  3  G  H6"; 
this  complex  proportion  becomes  somewhat  more  simple  if 
we  tal^e  the  new  equivalent,  when  we  find  it  to  be  G  C,  H 

+  4-GH. 

In  the  same  volume  is  also  a  paper  by  Ch.  Gmelin  on  some 
properties  of  glucina. 

Action  of  Water  on  certain  Sulphurets  and  haloid  Salts. 

H.  Rose  has  published  a  most  interesting  paper  on  this 
subject ;  most  of  the  experiments  were  made  with  sulphuret 
of  barium,  which  was  prepared  by  strongly  heating  a  mixture  of 
charcoal  and  sulphate  of  baryta.  tThe  black  mass  was  treated 
in  a  closed  bottle  with  a  quantity  of  water  far  insufficient  to 
dissolve  all  the  sulphuret ;  after  standing  twenty-four  hours  it 
was  decanted  and  a  fresh  portion  added,  and  this  repeated 
nine  times ;  each  portion  was  kept  separate.  The  first  and 
second  solutions  contained  hydrosulphuret  of  barium  (H  S, 
Ba  S),  which  was  proved  by  the  evolution  of  sulphuretted  hy- 
drogen, on  adding  to  them  a  concentrated  neutral  solution  of 
sulphate  of  manganese;  the  sulphur  was  oxidized  by  treating 
the  salt  with  hydrochloric  acid  and  passing  the  sulphuretted 
hydrogen  into  strong  nitro-hydrochloric  acid  ;  the  sulphur  was 
thus  perfectly  oxidized.  A  stream  of  air  was  passed  through 
the  solution  to  carry  over  all  the  hydrosulphuric  acid,  and 
then  chlorine  passed  into  it  to  oxidize  any  sulphur.-  The 
oxidized  fluids  mixed  together,  the  sulphate  of  baryta  sepa- 
rated; in  the  filtered  liquor  a  large  precipitate  was  produced 
by  chloride  of  barium.  The  third  solution  gave  only  a  slight 
smell  of  H  S,  with  sulphate  of  manganese,  but  a  copious  evo- 
lution with  hydrochloric  acid.  Chloride  of  barium  (as  above) 
produced  only  a  slight  precipitate;  it  contained  therefore 
sulphuret  with  a  small  portion  of  hydrosulphuret.  The  fourth 
gave  no  trace  of  S  H  with  sulphate  of  manganese,  abundance 
with  hydrochloric  acid ;  no  precipitate  was  produced  by  chlo- 
ride of  barium,  but  a  slight  one  by  sulphuric  acid ;  it  con- 
tained therefore  sulphuret  and  baryta.  The  fifth  contained 
less  sulphuret  and  more  baryta,  and  the  others  only  a  trace 
of  sulphuret.  When  large  quantities  of  sulphuret  of  barium 
are  boiled  with  water  the  same  products  are  obtained ;  some- 
times hydrate  of  baryta  crystallizes,  sometimes  sulphuret,  and 
sometimes  compounds  of  both ;  the  hydrosulphuret  is  the  most 
soluble  product.     The  composition  of  one  compound,  which 


Notices  of  the  Labours  of  Continental  Chemists. 

formed  good  crystals,  was  Ba  H10  +  3  Ba  S,  H6.     Another 

gave  the  formula  4  Ba  H10  +  3  Ba  S,  H6;  a  third  appeared  to 

be  Ba  H10  +  Ba  S,  H10;  but  it  is  possible  that  the  last  two 
were  only  mixtures. 

Sulphuret  of  barium  crystallizes  with  six  atoms  of  water ; 
water  acts  upon  this  salt  in  the  same  manner  as  upon  the  re- 
duced sulphate  of  baryta.  The  sulphuret  can  hardly  be  ob- 
tained free  from  hydrate  of  baryta.  The  solid  hydrosulphuret 
of  barium  was  not  analysed,as  it  cannot  be  obtained  free  from 
supersulphurets,  sulphuret  and  hydrate  of  baryta. 

It  appears  therefore  that  sulphuret  of  barium  is  decom- 
posed by  water  and  forms  hydrosulphuric  acid  and  baryta ; 
the  affinity  which  the  H  S  has  for  the  sulphuret  causes  the 
separation  of  baryta,  which  crystallizes,  sometimes  as  hydrate, 
and  at  other  times  in  combination  with  the  sulphuret. 

Sulphuret  of  strontium,  as  formed  from  sulphate  and  char- 
coal, is  decomposed  in  the  same  manner  as  that  of  barium  ;  the 
more  difficult  solubility  of  the  hydrate  of  strontia  causes  it  to 
be  separated  from  the  other  salts  with  great  ease.  H.  Rose 
could  obtain  neither  sulphuret  of  strontium  nor  its  com- 
pound with  strontia ;  the  sulphuret  is  decomposed  by  boiling 
into  the  earth  and  the  hydrosulphuret.  Hydrate  of  strontia 
contains  10  atoms  of  water,  which  agrees  with  the  statements 
of  Phillips  and  Noad* ;  the  baryta  compound  also  contains  10 
atoms. 

Sulphuret  of  calcium  was  prepared  by  heating  the  sulphate 
with  charcoal;  the  mass  when  heated  with  water  furnishes 
solely  hydrosulphuret  and  hydrate  of  lime;  the  principal  cause 
of  this  appears  to  lie  in  the  insolubility  of  the  hydrate.  On 
boiling  the  solution  of  the  hydrosulphuret  in  a  retort,  hydro- 
sulphuric  acid  is  evolved  and  lime  precipitated ;  on  further 
evaporation  the  solution  assumes  a  yellow  colour;  a  white 
powder,  sulphite  of  lime,  is  often  precipitated,  formed  from 
the  hyposulphite  produced  by  the  boiling.  In  the  concen- 
trated solution  long' golden  yellow  crystals  are  formed,  they 
are  very  small  in  quantity  although  large  in  volume.  The 
crystals  evolve  no  hydrosulphuric  acid  when  treated  with  sul- 
phate of  manganese,  but  only  with  acids,  sulphur  being  sepa- 
rated ;  treated  with  a  large  quantity  of  water  they  leave  behind 
a  quantity  of  lime.  When  heated  they  give  off  water  and 
sulphur ;  the  residue  treated  with  acid  gives  sulphur  and  hy- 
drosulphuric acid.  The  formula  of  this  compound  is  Ca  S5 
+  5  Ca  O  +  20  aq. — (Pogg.  Ann.^  vol.  lv.  pp.  415-437.) 
•  See  Phil.  Mag.,  Third  Series,  vol.  xi.  p.  301.— Ed. 


Action  of  Water  on  Sulpkurets  and  haloid  Salts.       287 

In  a  second  paper  H.  Rose  takes  into  consideration  the 
long-disputed  point,  whether  the  haloid  salts  and  sulphurets 
decompose  water  when  dissolved.  Judging  from  analogy 
and  the  example  of  the  sulphuret  of  barium,  one  would  sup- 
pose that  sulphuret  of  potassium  would  be  decomposed  with 
water  into  hydrosulphuret  and  caustic  potassa ;  the  solution 
of  this  sulphuret  turns  red  litmus  paper  blue ;  and  by  its  solu- 
tion in  water  heat  is  evolved,  and  we  do  not  know  that  sul- 
phuret of  potassium  combines  with  water  of  crystallization. 
Rose  concludes  that  the  higher  sulphurets  are  not  decom- 
posed by  water.  The  compounds  of  fluorine  are  so  similar 
to  those  of  sulphur  that  we  might  almost  be  justified  in  placing 
fluorine  in  a  class  with  sulphur  and  not  with  chlorine ;  it  is 
possible  that  on  dissolving  fluoride  of  potassium  in  water, 
potassa  and  hydrofluoride  are  formed.  Rose  could  not  ob- 
tain them  separate,  but,  as  is  well  known,  the  solution  reacts 
alkaline  and  also  attacks  glass.  The  fluoride  of  ammonium 
gives  ammonia  and  hydrofluoride. 

Chlorides  of  potassium,  sodium  and  ammonium  produce 
a  considerable  degree  of  cold  when  dissolved  in  water,  and 
hence  we  may  conclude,  that  on  the  solution  of  these  salts 
water  is  not  decomposed.  Chloride  of  calcium  evolves  heat 
when  dissolved,  and  Thenard  and  Gay-Lussac  adduced  this 
to  prove  the  decomposition  of  water,  but  it  is  simply  a  com- 
bination of  the  salt  with  water  of  crystallization.  Chloride  of 
sodium  produces  less  cold  than  chloride  of  ammonium,  but 
we  know  that  under  certain  circumstances  the  former  can 
combine  with  four  atoms  of  water.  The  same  is  the  case  with 
several  oxysalts. 

Rose  has  found  that  chlorides  of  antimony  and  bismuth 
evolve  heat  when  dissolved,  and  supposes  that  they  decompose 
water.  As  a  general  approximate  rule  we  may  say,  that  all 
compounds  of  bromine,  chlorine,  iodine,  cyanogen  and  sul- 
phocyanogen  with  metals  which  are  equivalent  to  the  basic 
oxides,  dissolve  in  water  without  decomposition,  while  those 
that  represent  the  acid  oxides  decompose  water.  Fluoride  of 
potassium  evolves  heat,  but  it  combines  with  water  ;  the  hy- 
drated  salt  may  be  obtained  by  gentle  evaporation,  or  by 
adding  alcohol  to  a  solution  of  the  fluoride  ;  it  contains  four 
atoms  of  water. —  (Pogg.  Ann.,  vol.  lv.  pp.  534,  557.) 

It  is  impossible  to  give  any  but  an  imperfect  report  of  this 
most  excellent  paper  in  these  notices  without  exceeding  our 
limits ;  we  must  most  earnestly  recommend  the  perusal  of  the 
original  to  all  chemists. 


[  288  ] 

XLIX.  On  the  Occurrence  of  Shells  and  Corals  in  a  Conglo- 
merate Bed,  adherent  to  the  face  of  the  Trap  Rocks  of  the 
Malvern  Hills,  and  full  of  rounded  and  angular  fragments 
of  those  rocks.     By  John  Phillips,  Esq.,  F.R.S.,  fyc. 

THE  researches  of  Sir  H.  T.  De  la  Beche  during  the  autumn 
of  184<1  into  the  nature,  antiquity  and  organic  contents 
of  the  trappfean  ash-beds  of  North  Pembroke,  coupled  with 
other  parallel  inquiries,  have  excited  in  the  minds  of  those 
persons  who  are  attached  to  the  Ordnance  Geological  Survey 
a  lively  interest  in  the  study  of  the  relations  between  trap 
rocks  and  the  strata  amongst  which  they  appear.  A  very  com- 
mon result  of  this  study  in  South  Wales  is  a  conviction  of 
the  rarity  of  irruptive  trap  and  the  frequency  of  interstratified 
(and,  in  ordinary  language,  contemporaneous)  beds  of  plu- 
tonic  rocks  and  felspatho-hornblendic  sediments,  which  are 
not  always  clearly  distinguished  from  the  fused  rocks.  On 
these  points  in  the  same  or  neighbouring  districts,  Professor 
Sedgwick  and  Mr.  Murchison  deliver  nearly  the  same  judg- 
ment. 

The  great  obligations  which  geology  owes  to  Mr.  Leonard 
Horner  and  to  Mr.  Murchison  for  their  descriptions  of  the 
fused  and  sedimentary  rocks  in  this  chain,  and  of  the  grand 
movements  in  the  crust  of  the  earth,  of  which  it  is  a  noble 
monument,  are  universally  admitted,  but  demand  a  glad  ac- 
knowledgement from  one  who,  following  in  their  steps  and 
profiting  by  their  experience,  desires  to  join  to  theirs  the 
additional  information  which  he  may  be  so  fortunate  as  to 
gather. 

After  finishing  the  colouring  of  a  great  part  of  the  Ord- 
nance map  of  this  district,  I  turned  to  examine  with  care  and 
interest  the  great  problem  which  the  Malvern  hills  present, 
viz.  the  determination  of  the  circumstances  under  which  the  plu- 
tonic  rocks  were  elevated.  For  this  purpose  the  appearance 
of  the  fused  and  sedimentary  rocks  in  every  part  of  the  Mal- 
vern chain  and  the  surrounding  country  has  been  considered, 
separately  and  in  combination  ;  and  the  general  result  is,  that 
the  elevation  of  these  hills  is  a  part  of  that  grand  series  of 
associated  movements,  which  the  Director  and  other  mem- 
bers of  the  Geological  Survey  have  been  tracing  between  St. 
Bride's  Bay  and  the  Severn,  between  the  Teivy  and  the  Bris- 
tol Channel. 

Viewed  in  this  association,  the  geological  epoch  when  the 
great  movement  of  the  Malvern  rocks  occurred,  becomes  de- 
terminable, and  has  in  fact  been  determined  by  the  eminent 
geologists  already  named.     No  one  can  witness  the  many 


On  Shells  and  Corals  in  a  Conglomerate  at  Malvern.     289 

anticlinal  and  synclinal  curvatures  which  on  the  western  flank 
of  the  Malverns  affect  equally  the  Silurian  and  old  red  forma- 
tions, and  then  survey  the  comparatively  horizontal  and  un- 
moved strata  of  new  red  marls  and  sandstones,  which  on  the 
east  and  south  touch  indiscriminately  the  sienites,  Caradoc 
sandstones,  Wenlock  limestone,  and  old  red  sandstone,  with- 
out being  satisfied  that  the  great  upward  movement  of  the 
Malvern  rocks  happened  in  the  interval  between  the  old  and 
the  new  red  sandstones. 

But  in  what  state  were  these  plutonic  masses  raised  ?  as 
fused  and  liquid  matter,  or  solidified  rock?  To  determine  this 
question,  the  observed  positions  of  the  strata  which  adjoin  the 
trap  range  are  important,  but  their  condition  and  contents  are 
still  more  essential.  My  first  expectation,  on  looking  gene- 
rally at  the  narrow  continuous  range  of  the  Malverns,  was, 
that  here  might  be  found  an  example  of  a  gigantic  sinuous 
mass,  emitted  in  a  liquid  state  along  a  portion  of  that  great 
irregular  fracture  which  is  the  western  boundary  of  the  new 
red  sandstone,  from  the  Severn  to  the  Dee.  The  complicated 
nature  of  the  trap,  its  innumerable  vein-like  segregations,  its 
included  gneissic  beds,  gave  an  additional  interest  to  the  ex- 
amination of  the  appearances  at  and  near  the  junction  of  the 
trap  with  the  exterior  stratified  masses. 

In  aid  of  this  inquiry  I  fortunately  discovered  two  re- 
markable localities  where  Silurian  strata  of  determinate  age 
were  in  contact  with  the  trap  masses;  one  exposed  in  the 
deep  cutting  at  the  Wych,  the  other  on  the  depressed  sum- 
mit of  drainage  between  the  Hereford  beacon  and  Swin- 
yard  hill.  Besides  these  are  several  examples  of  the  sedi- 
mentary aggregates  of  the  lower  Silurian  strata  in  juxtaposi- 
tion or  actual  contact  with  the  trap  rocks  of  the  high  Malvern 
ridge;  with  a  detached  series  of  low  insulated  ridges  and 
bosses  of  trap  on  the  western  side  near  the  southern  extre- 
mity of  the  chain ;  and  with  some  low  mounds  described  by 
Mr.  Murchison  at  the  northern  extremity. 

The  appearances  connected  with  the  low  points  at  the 
northern  end,  and  with  a  part  of  the  ridge  near  the  southern 
extremity,  have  been  considered  to  indicate  metamorphism  in 
stratified  rocks  by  heat*;  and  the  phsenomena  associated 
with  the  detached  bosses  and  hillocks  on  the  western  side 
of  the  chain,  may  be  believed  to  indicate  irruption  of  trap 
amongst  the  lowest  of  the  Silurian  strata ;  but  generally  along 
the  chain  itself,  and  especially  in  all  the  northern  parts  of  it, 
there  appears  no  evidence  that  the  adjacent  exterior  strata 
have  been  invaded  by  liquid  irruptive  rock. 

*  Murchison's  Silurian  System,  p.  417  etaeq. 

Phil.  Mag.  S.  3.  Vol.  21 .  No.  1 38.  Oct.  184-2.  U 


290      Mr.  J.  Phillips  on  a  Fossiliferous  Conglomerate. 

In  the  deep  cutting  at  the  Wych,  sandstones  and  shales  of 
the  Caradoc  formation  are  placed  in  a  singular  manner  between 
masses  of  trap,  but  are  entirely  unchanged  in  aspect,  and  re- 
tain the  usual  organic  remains.  On  the  summit  ridge  near 
Swinyard  hill,  the  upper  beds  of  the  Caradoc  series,  with  the 
usual  limestone  bands  and  shales  of  that  part  of  the  Silurian 
strata,  rest  against  solid  felspathic  trap  on  the  south  side  and 
cover  it  as  with  a  saddle.  The  corals  and  shells  here  gathered 
were  in  their  usual  state,  and  the  strata  appear  unaltered. 

Contrasting  these  cases  with  others  in  the  midst  of  the 
Malvern  hills,  where  stratified  rocks  are  irregularly  mixed 
with  the  fused  rocks,  and  have  the  character  of  gneiss,  and  with 
others  on  the  western  flanks  where  dykes  and  bosses  of  trap 
appear  amongst  peculiar  sandstones  and  black  shales,  it  ap- 
peared probable  that  some  parts  at  least  of  the  Malvern  ridge 
were  of  higher  antiquity  than  any  of  the  exterior  strata  ;  that 
amongst  the  lowest  of  these  strata,  local  and  limited  irruptions 
of  a  different  sort  of  trap  had  occurred ;  but  that  the  greater 
part  of  the  Silurian  strata  visible  in  the  northern  parts  of  the 
hills  had  been  subject  to  no  peculiar  heat  emanating  from  the 
Malvern  ridge. 

In  this  condition  of  the  argument  Mr.  Murchison  and 
Count  Keyserling  passed  through  Malvern  and  inspected  the 
section  of  the  Wych,  as  well  as  the  north  end  of  the  Malverns, 
and  Professor  Sedgwick  accompanied  me  on  a  leisurely  survey 
of  this  and  other  points  further  south.  On  the  day  (Au- 
gust 1)  while  I  was  enjoying  the  advantage  of  his  experience 
in  examining  the  facts  thus  briefly  adverted  to,  a  discovery 
was  made  which  threw  a  new  and  concentrated  light  on  the 
phaenomena  we  were  discussing. 

My  sister,  knowing  the  interest  I  felt  in  tracing  out  the  hi- 
story of  the  stratification  visible  in  these  trap  hills,  sought  dili- 
gently for  organic  remains  in  the  midst  of  and  on  the  western 
flanks  of  the  sienitic  masses  of  the  North  hill  and  Sugar-loaf 
hill.  In  this  most  unpromising  search  she  was  entirely  suc- 
cessful, and  collected  from  the  midst  of  heaps  of  fallen  stones, 
which  seemed  to  be  all  trap,  several  masses  richly  charged 
with  organic  remains,  and  full  of  felspar,  quartz,  and  horn- 
blende, in  grains  and  large  lumps.  On  careful  examination, 
it  was  seen  that  those  lumps  were  fragments,  generally  rolled 
to  pebbles,  and  distributed  with  reference  to  one  another  and 
to  the  shells,  just  as  quartz  pebbles  and  chips  are  in  a  com- 
mon conglomerate.  It  was,  in  fact,  certainly  and  evidently 
a  conglomerate  full  of  Silurian  shells,  and  pebbles  and  frag- 
ments of  the  sienitic,  felspatho-quartzose  and  other  rock- 
masses  of  the  Malvern  hills. 


adherent  to  the  Trap  of  the  Malvern  Hills.  291 

The  next  thing  to  determine  was  the  position  of  this  con- 
glomerate in  relation  to  the  ridge  of  sienitic  rocks  amongst 
the  detritus  of  which  its  fragments  lay.     This  was  difficult. 


We.t. 


East. 


12 


The  abundance  of  detritus  on  all  the  slopes  is  so  great  as  to 
conceal  for  the  most  part  the  junction  of  the  stratified  and 
unstratified  rocks.  The  loose  shelly  pieces  we  found  abun- 
dantly for  fully  one-third  of  a  mile  along  the  mountain  side,  and 
at  length  the  conglomerate  rock  itself  was  plainly  seen  ad- 
hering to  the  extreme  western  nearly  vertical  face  of  the  trap 
mass,  west  of  the  Worcestershire  beacon,  in  a  situation  con- 
tiguous to  a  large  excavation  of  the  lower  Caradoc  sandstone. 
These  facts  ascertained,  I  waited  for  the  arrival  of  Sir  H. 
T.  De  la  Beche  at  Malvern,  to  have  the  shelly  bed  thoroughly 
explored,  and  its  contact  with  the  trap  rocks  carefully  traced. 
We  found  the  surface  of  the  trap  nearly  vertical,  but  undu- 
lating and  irregular,  and  its  strike  nearly  north  and  south ; 
the  rock  is  here  hornblendic,  dark  green  or  purplish  in  co- 
lour, and,  as  usual  in  all  these  hills,  it  is  within  short  distances 
mixed  and  variegated  with  more  felspathic  portions,  felspatho- 
quartzose  veins,  &c.  Closely  adhering  to  it  was  usually  a 
softish  laminated  clay ;  bedded  in  the  clay,  or  touching  the 
trap  rock,  were  multitudes  of  rolled  pebbles  and  angular  chips 
and  fragments  of  stone,  accumulated  in  an  irregular  bed  above 

U  2 


292     On  Shells  and  Corah  in  a  Conglomerate  at  Malvern. 

a  foot  or  only  a  few  inches  in  thickness  against  the  trap.  In 
the  intervals  of  these  pebbles  were  partial  admixtures  of  ar- 
gillaceous shale,  abundance  of  shells,  and  smaller  chips  and 
fragments  of  stone,  more  or  less  stained  brown,  in  the  same 
manner  as  commonly  happens  in  shelly  cavities  in  other  con- 
glomerates and  sandstones  far  removed  from  the  trap.  Ex- 
terior to  this  very  pebbly  mass,  the  shells  were  equally  nume- 
rous, but  the  rock  fragments  amongst  which  they  lay  were 
generally  angular,  appearing  just  as  if  they  had  fallen  from  a 
cliff  upon  a  pebbly  beach,  and  received  into  their  interstices 
abundance  of  shells  and  sand  drifted  by  the  water. 

The  degree  ofjirmness  of  the  shelly  masses  thus  examined 
in  situ,  is  less  on  an  average  than  that  of  the  loose  pieces  on 
the  hill  slopes  which  were  first  observed ;  these  latter  being 
the  hardest  portions  which  best  withstood  destroying  agencies. 

The  shells,  corals  and  encrinites,  are  commonly  represented 
by  casts  and  moulds,  but  a  few  specimens  have  occurred  of 
Turbinolopsis,  with  the  calcareous  substance  entirely  pre- 
served. 

The  pebbles  and  fragments  of  stone  mixed  with  the  shells 
are  of  the  same  nature  as  the  rocks  immediately  adjacent  and 
composing  the  neighbouring  hills;  that  is  to  say,  characteristic 
compounds  and  segregations  of  hornblende,  felspar,  quartz, 
and  mica,  in  great  variety.  The  whole  mass  is  stained  by  fer- 
ruginous admixtures,  and  at  a  small  distance  looks  like  some 
of  the  dark  trap  of  the  hills  with  which  it  is  in  contact.  What 
may  be  its  degree  of  induration  at  a  considerable  depth  is 
unknown,  the  situation  allowing  only  of  an  exploration  to  the 
depth  of  a  few  feet. 

The  just  inference  from  the  occurrence  of  the  shelly  con- 
glomerate thus  briefly  described,  appears  to  be  that  the  sie- 
nitic  and  other  associated  rocks  of  the  northern  portion  of 
the  Malvern  hills  were  accumulated  and  indurated  previous 
to  the  aggregation  of  the  lower  portions  of  the  Caradoc  sand- 
stone series;  and  that  they  were,  with  the  whole  Silurian  series, 
raised  in  a  solid  state. 

In  harmony  with  this  conclusion,  is  the  abundance  of  frag- 
ments and  disintegrated  grains  of  the  Malvern  rocks  in  other 
conglomerates  (not  shelly)  of  the  Caradoc  series,  about  the 
north  end  of  the  chain,  examined  by  Sir  H.  T.  De  la  Beche 
and  myself.  Even  in  Ankerdine  hill,  eight  miles  north  of 
Malvern,  fragments  of  the  sienitic  rocks  were  observed  in  the 
Caradoc  sandstone  by  Capt.  James,  R.E.,  and  myself;  and 
the  conglomerate  of  May  hill  yielded  similar  results  to  Sir 
H.  T.  De  la  Beche. 

Observations  of  this  nature,  combined  with  accurate  sur- 


Prof.  MacCullagh  on  the  Dispersion  of  Optic  Axes,  tyc.   293 

veys  of  the  great  lines  of  subterranean  movement,  may  here- 
after enlarge  the  limited  view  now  presented  of  a  part  of  the 
Malvern  hills,  into  a  general  contemplation  of  the  agency  of 
heat  during  the  Palaeozoic  periods  in  the  great  physical  re- 
gion between  the  vale  of  the  Severn  and  the  coasts  of  Wales. 
But  to  state  such  a  speculation  without  the  data  which  have 
been  collected  for  its  illustration,  would  be  useless  or  injuri- 
ous, and  the  constitution  of  even  the  Malvern  chain  itself  is 
sufficiently  varied  in  its  different  parts,  to  induce  a  long  pause 
before  the  apparently  proved  high  antiquity  of  the  northern 
sienites  should  be  implicitly  extended  even  to  the  southern 
portion  of  the  same  chain. 
Malvern,  Sept,  19,  1842. 

L.  On  the  Dispersion  of  the  Optic  Axes,  and  of  the  Axes  of 
Elasticity,  in  Biaxal  Crystals.  By  James  MacCullagh, 
LL.D.,  M.R.I.A.,  Fellow  of  Trinity  College,  and  Professor 
of  Mathematics  in  the  University  of  Dublin*. 

TN  the  last  Number  of  the  Philosophical  Magazine  (p.  228), 
-■-  there  appeared  an  extract  from  the  Proceedings  of  the  Royal 
Irish  Academy,  containing  a  notice  of  a  memoir  which  I  had 
the  honour  of  reading  to  that  body  on  the  24th  of  May,  1841 ; 
and  in  the  concluding  paragraph  of  the  notice  a  brief  allusion 
is  made  to  a  K  mathematical  hypothesis"  by  which  I  had  con- 
nected the  laws  of  dispersion  and  those  of  the  elliptic  polari- 
zation of  rock-crystal  with  the  other  laws  that  were  there  an- 
nounced. My  present  object  is  to  indicate  the  development 
of  that  hypothesis,  with  reference  more  particularly  to  the 
subject  of  dispersion  in  crystals,  and  to  communicate  a  very 
simple  result  which  I  have  lately  had  occasion  to  obtain  from 
it.  The  result  is  remarkable  as  embracing  and  explaining  a 
class  of  intricate  phaenomena  which  hitherto  have  not  been 
connected  with  any  theory,  or  rather  have  stood  in  opposition 
to  all  theories ;  I  mean  the  phaenomena  of  the  dispersion  of 
the  optic  axes,  and  of  the  axes  of  elasticity  (as  they  are  called) 
in  biaxal  crystals. 

The  name  of  axes  of  elasticity  was  given  by  Fresnel  to  three 
rectangular  directions,  which,  according  to  his  theory,  exist  in 
every  crystallized  medium,  and  which  are  distinguished  by  the 
property,  that  if  a  particle  of  the  medium  be  slightly  displaced 
in  the  direction  of  any  one  of  them,  the  elastic  force  thereby 
called  into  play  will  act  precisely  in  the  line  of  the  displace- 

.  *  Communicated  by  the  Author. 


294     Prof.  MacCullagh  on  the  Dispersion  of  the  Optic  Axes, 

nient.  These  directions  coincide  with  the  axes  of  the  ellipsoid 
by  which  he  constructs  his  wave-surface ;  and  the  position  of 
the  axes  being  thus  fixed,  it  is  only  their  lengths  that  can  be 
supposed  to  vary  for  the  differently  coloured  rays.  Such  is  the 
view  taken  by  Fresnel  with  regard  to  crystalline  dispersion, 
and  it  is  obviously  the  only  view  that  his  theory  admits.  Suc- 
ceeding theorists,  in  their  numerous  attempts  to  deduce 
Fresnel's  beautiful  laws  from  dynamical  principles,  have  al- 
ways been  obliged  to  assume  that  the  medium  is  symmetrically 
arranged  with  respect  to  three  rectangular  planes ;  and  as,  in 
this  hypothesis,  the  axes  of  elasticity,  or  of  optical  symmetry, 
necessarily  coincide  with  those  of  symmetrical  arrangement, 
their  directions  are  fixed,  as  before,  independently  of  colour. 

From  these  principles  it  follows  that  the  optic  axes  for  dif- 
ferent colours  all  lie  in  the  same  plane,  namely,  the  plane  of 
the  greatest  and  least  axes  of  the  ellipsoid,  and  that  they  are 
equally  inclined  to  each  of  the  latter  axes,  so  that  the  angle 
made  by  any  pair,  to  whatever  colour  they  belong,  is  always 
bisected  by  the  same  right  line.  This  was  accordingly,  for  a 
long  time,  believed  to  be  the  case ;  and  the  earlier  experi- 
ments of  Sir  J.  Herschel  (Phil.  Trans.  1820)  which  are  ap- 
pealed to  by  Fresnel,  as  well  as  the  observations  of  Sir  David 
Brewster,  seemed  to  establish  it  as  a  general  law.  But  it  was 
afterwards  discovered  by  Sir  J.  Herschel,  that,  in  borax,  the 
optic  axes  for  different  colours  lie  in  different  planes  inclined 
at  very  sensible  angles  to  each  other ;  and  the  same  discovery 
was  made  about  the  same  time  (1832)  by  M.  Norrenberg. 
The  latter  observer  further  ascertained,  that  even  when  the 
optic  axes  all  lie  in  the  same  plane,  there  are  cases,  as  in  sul- 
phate of  lime,  wherein  their  angles  are  not  bisected  by  the 
same  right  line.  These  facts,  and  others  of  a  like  nature  that 
have  been  since  observed,  show  the  falsehood  of  the  suppo- 
sition that  the  lines  called  the  axes  of  elasticity  have  always 
the  same  directions  whatever  be  the  colour  of  the  light;  they 
are  inconsistent  with  all  received  notions,  and  contradict  every 
theory  that  has  been  hitherto  proposed.  No  person,  as  far 
as  I  am  aware,  has  even  attempted  to  explain  them. 

But  in  the  theory  which  I  have  constructed  to  represent 
the  laws  of  the  action  of  crystallized  bodies  upon  light,  and 
which  has  already  brought  so  much  within  its  grasp,  the 
phenomena  in  question  do  not  offer  any  difficulty  whatever; 
on  the  contrary,  they  are  of  a  kind  that  would  naturally  be 
looked  for,  antecedently  to  experiment.  For  in  this  theory, 
I  make  no  hypothesis  as  to  the  constitution  of  the  sether,  or 
the  arrangement  of  its  molecules ;  nor  any  hypothesis,  like 


and  of  the  Axes  of  Elasticity,  in  Biaxal  Crystals.      295 

that  of  Fresnel,  respecting  the  mechanical  signification  of  the 
axes  of  elasticity.  The  existence  of  three  rectangular  axes 
possessing  peculiar  properties  is  not  a  principle,  but  a  result, 
of  theory ;  their  directions  are  determined  by  conditions  per- 
fectly analogous  to  those  which  determine  the  principal  axes 
of  an  ellipsoid  from  its  general  equation ;  and  these  directions 
are  functions  of  certain  quantities  which  are  constant  when 
differentials  of  the  second  and  subsequent  orders  are  neg- 
lected, but  which  vary  when  these  are  taken  into  account.  The 
differentials  of  higher  orders  introduce  terms  depending  on 
the  wave-length ;  and  thus  the  directions,  as  well  as  the  lengths, 
of  the  principal  lines  depend  on  the  colour  of  the  light,  or,  to 
speak  more  accurately,  on  the  length  of  the  wave. 

All  this  will  be  easily  understood  if  we  recur  to  the  first 
principles  of  the  theory.  According  to  these,  everything  de- 
pends on  the  form  assigned  to  the  function  V  in  the  general 
dynamical  equation 

Jffi^d^i+d^+d^n)=fffd^yMy, 

from  which  the  motion  of  the  aether  is  deduced.  In  my  first 
memoir  on  the  subject  (read  to  the  Academy  on  the  9th  of 
December,  1839),  I  showed  that  when  differentials  of  the 
first  order  only  are  preserved,  the  function  V — which  may 
perhaps  with  propriety  be  called  the  potential,  since  the  mo- 
tion of  the  system  is  potentially,  or  virtually,  included  in  it — 
is  a  function  of  the  second  degree,  composed  of  the  three 
quantities  X,  Y,  Z,  which  are  connected  with  the  displace- 
ments £,  ij,  f  by  the  following  relations : — 

x_d_>?__£?jr  y=— —  —  Z  —  ~  —  — 

~~  dz      dy9  ~  dx      dz  ~  dy      dx' 

To  show  this,  I  make  use  simply  of  the  consideration  that  the 
motion  must  be  such  as  to  satisfy  the  condition 

d%       dr)       d£       „ 
dx       dy      dz         ' 

which  seems  to  be  characteristic  of  the  vibrations  of  light. 
But  the  same  condition  allows  us  to  suppose  that  the  poten- 
tial contains  not  only  the  quantities  X,  Y,  Z,  but  their  dif- 
ferential coefficients  of  any  order  with  respect  to  the  coordi- 
nates. This  supposition,  however,  is  too  general,  and  re- 
quires to  be  limited  by  other  considerations.  Now  the  most 
natural  restriction  which  can  be  imposed  consists  in  the  as- 
sumption that  the  quantities  of  all  orders  are  formed  on  the 
same  type,  those  of  any  order  being  derived  from  the  prece- 


296    Prof.  MacCullagh  on  the  Dispersion  of  Optic  Axes,  Sf-c. 

ding  in  the  same  way  that  the  quantities  X,  Y,  Z  are  derived 
from  £,  >j,  £;  there  are  particular  reasons  also  which  go  to 
strengthen  this  hypothesis,  and  have  led  me  to  adopt  it. 
Putting  therefore 

X-^_^?      V  _  rL?  _  ^5      7_</X      dY 
*~  dz       dy>        1_  dx       dz'        x~  dy        dx' 


X 


rfY,      dZl  __dZl_dX1         _dXl      dY} 


2       d ,?       rfz/'        2      d  .r        dz*       2       */  y        d  .r ' 

and  so  on,  I  suppose  the  potential  to  be  a  function  of  the  se- 
cond degree,  composed  of  all  the  quantities  X,  Y,  Z,  X1}  Y15 
Z1S  X2,  Y2,  Z2,  &c;  and  this  is  the  "mathematical  hypothe- 
sis "  alluded  to  in  the  beginning  of  this  article.  The  hypo- 
thesis occurred  to  me  more  than  three  years  ago  (June  1839), 
but  I  did  not  venture  to  communicate  it  to  the  Academy  until 
the  date  of  my  second  memoir  (May  1841);  and  even  then  I 
had  not  studied  it  with  the  attention  which  I  now  conceive  it 
merits.  It  was  only  very  lately,  in  fact,  in  some  conversations 
which  I  had  with  M.  Babinet  during  a  short  visit  to  Paris, 
that  my  attention  was  strongly  drawn  to  the  subject  of  disper- 
sion in  crystals,  particularly  the  dispersion  of  the  axes  of 
elasticity.  My  thoughts  then  naturally  reverted  to  the  hy- 
pothesis which  I  have  mentioned,  and  since  my  return  I  have 
found  that  it  affords  a  complete  explanation  of  all  the  phae- 
nomena  *. 

I  have  also  found  that  it  gives  the  general  law,  extended  to 
biaxal  crystals,  of  that  elliptic  and  circular  polarization  which 
has  hitherto  been  detected  only  in  quartz  and  in  certain 
fluids;  while  for  the  case  of  rectilinear  polarization  it  gives  a 
law  (very  possibly  a  true  one)  more  general  than  that  of 
Fresnel,  but  quite  as  elegant,  and  differing  very  slightly  from 
it.  The  hypothesis,  therefore,  is  still  too  general  for  our 
present  purpose.  To  make  it  include  only  those  crystals  to 
which  the  law  of  Fresnel  is  rigorously  applicable,  the  alter- 
nate derivatives  X15  Yv  Zj,  X3,  Y3,  Z3,  &c.  must  be  supposed 
to  vanish  in  the  function  which  represents  the  potential. 
Then,  the  axes  of  coordinates  having  any  fixed  directions 
within  the  crystal,  the  axes  of  elasticity  will  be  the  principal 
axes  of  an  ellipsoid  represented  by  an  equation  of  the  form 

AxZ+ByZ  +  CzZ+ZDijz+ZExz  +  2Fxy  =  1, 

*  I  am  indebted,  for  my  information  on  the  subject,  to  a  short  article, 
drawn  up  by  MM.  Quetelet  and  Babinet,  in  the  'Bulletin  of  the  Royal 
Academy  of  Brussels,  vol.  ii.  p.  150;  as  also  to  PcggendorfTs  Annals, 
vol.xxvi.  p.  309  ;  vol.  xxxv.  p.  81. 


Mr.  G.  G.  Stokes  on  the  'Rectilinear  Motion  of  Fluids.  297 

in  which  each  of  the  six  coefficients,  the  first,  for  example,  ex- 
presses a  series  of  the  form 

K*$+% +■$  +  *« 

where  X  denotes  the  wave-length,  and  all  the  other  quantities 
are  constant.  The  ellipsoid  itself  is  the  reciprocal  of  that 
ellipsoid  by  which  the  wave-surface  is  constructed,  and  its 
semiaxes  are  the  three  principal  indices  of  refraction.  As  X 
is  supposed  to  vary,  not  only  the  length  but  the  direction  of 
the  principal  axes  vary,  and  thus  we  have  a  different  wave- 
surface  for  every  different  wave-length  within  the  crystal. 

The  optic  axes  are  perpendicular  to  the  circular  sections 
of  the  above  ellipsoid,  and  describe,  in  general,  two  fragments 
of  a  cone,  the  equation  of  which  may  be  found  by  supposing 
A  to  be  variable  in  the  equation  of  the  ellipsoid.  But  only 
very  particular  cases  have  been  hitherto  observed,  and  I  shall 
not  stop  to  discuss  them. 

Trinity  College,  Dublin,  J.  MacCullagh. 

September  1842. 

LI.  Remarks  on  a  paper  by  Professor  Challis,  "  On  the 
analytical  Condition  of  the  Rectilinear  Motion  of  Fluids." 
By  G.  G.  Stokes,  B.A.,  Fellow  of  Pembroke  College,  Cam- 
bridge*. 

TN  the  August  Number  of  this  Magazine  (p.  101),  Professor 
*■  Challis  has  written  an  article,  of  which  the  object  is  to 
prove  that,  in  all  cases  of  fluid  motion  in  which  udx  +  vdy 
+  wdz  is  an  exact  differential,  the  motion  is  rectilinear.  The 
importance  of  this  question  may  apologize  for  these  remarks, 
since,  if  the  reasoning  in  that  article  be  correct,  it  will  affect 
the  validity  of  much  that  has  been  written  on  the  subject.  It 
appears  to  me  however  that  Professor  Challis  has  made  an 
assumption  which  is  not  allowable,  and  consequently  the  con- 
clusion founded  on  it  is  not  allowable  either.  In  what  fol- 
lows, I  shall  call  the  path  of  a  particle  of  fluid  in  space  a  line 
of  motion,  and  a  line  traced  at  a  given  instant  from  point  to 
point  in  the  direction  of  the  motion  a  line  of  direction. 

As  the  basis  of  his  reasoning  Professor  Challis  assumes, 
that  in  every  case  where  the  continuity  of  the  fluid  is  main- 
tained, the  most  general  supposition  that  can  be  made  re- 
specting the  directions  of  motion  in  each  indefinitely  small 
element  of  the  fluid  is,  that  they  are  normals  to  a  surface  of 
continuous  curvature,  and  as  such  pass  ultimately  through 

*  Communicated  by  the  Author. 


298  Mr.  G.  G.  Stokes  on  the  Rectilinear  Motion 

two  focal  lines ;  that  is  to  say,  that  the  above  is  true  neglecting 
quantities  of  the  order  P  p2t  P  and  p  being  any  two  points  in  the 
element ;  that  this  is  the  meaning  is  shown  by  the  fact  that 
the  whole  investigation  depends  on  quantities  of  the  order  Pj9. 
Now,  not  only  in  the  case  where  udx  +  v  d y  +  w  d  z  is  an 
exact  differential,  but  also  in  the  case  where  it  is  integrable 
by  a  factor,  there  exists  a  surface  of  displacement  passing 
through  P,  and  the  above  statement  will  be  true  for  an  ele- 
ment of  this  surface.  But  it  will  not  generally  be  true  for  an 
element  of  three  dimensions;  for,  let p  be  taken  in  the  line  of 
direction  passing  through  P ;  then,  if  «x  be  the  radius  of  ab- 
solute curvature  of  this  line  at  the  point  P,  and  Pp  =  8  s, 
the  angle  between  the  tangents  at  P  and  p  will  be  ultimately 

8  s 

— .     Neglecting  quantities  of  the  order  8  s9,  a  line  PT'  drawn 
w 

through  P  parallel  to  the  tangent  at  P  may  be  taken  instead 

of  the  tangent  at  p.     Now,  even  if  we  suppose  the  line  P  T' 

to  pass  through  the  focal  line  which  is  at  a  distance  r  from 

p,  the  least  distance  between  it  and  the  other  focal  line,  which 

8s 
is  at  a  distance  r1  from  p,  will  be  ultimately  r'  — .      Hence, 

it  cannot  ultimately  pass  through  both  focal  lines,  unless  "ro- 
be at  every  point  infinite,  i.  e.  unless  all  the  lines  of  motion  be 
right  lines,  which  is  evidently  a  very  limited  case.  Conse- 
quently, it  is  only  in  this  case  that  it  is  proved  that  surfaces  of 
displacement  are  surfaces  of  equal  velocity. 

There  is  another  part  of  Professor  Challis's  reasoning  with 

which   I    cannot  agree.     It  is    that  d  (-rr)  or    , ,  ,     dx 
■  \dt  J        dtdx 

d*$     7  d?4>      ,  L    .  .       c 

+  — — ►*-  dy  +    ,     ,     d  n  —  0,  in  passing  from  one  point  to 

another  of  a  surface  of  displacement.     For,  d  ( —  \  m  0 

the  differential  equation  to  a  family  of  surfaces  whose  general 

equation  is  — j—  =  C,  which  family  of  surfaces  is  in  general 

quite  different  from  that  whose  equation  is  <p  =  0.  Now  the 
proof  requires  that  the  variations  dx>  dy,  dz  should  be  taken 
along  that  surface  of  the  second  family  which  passes  through 

the  point  {x,y,  z),  whereas  the  variations  for  which  d(  —  )  =  0, 

must  be  taken  along  that  surface  of  the  first  family  which 
passes  through  the  same  point.  If  <p  =  r[/  (t)  (.r2— j/2)+%  {t)xy9 
for  instance,  these  two  surfaces  will  be  different. 


is 


of  Fluids  as  investigated  by  Prof.  Challis.  299 

In  any  possible  case  of  fluid  motion,  the  motion,  which 
would  result  by  supposing  the  whole  mass  of  fluid  so  in  motion 
to  be  besides  moving  forward  in  space  with  a  uniform  velo- 
city, would  also  be  possible.  But  if  the  components  u,  v,  w 
of  the  velocity  in  the  first  case  be  such  that  udx  +  vdy  +  ivdz 
is  an  exact  differential,  it  will  be  easily  seen  that  the  com- 
ponents u'j  ?/,  id  of  the  velocity  in  the  second  case  will  also 
be  such  that  u'  dx  +  v1  dy  +  Do'  dz  will  be  an  exact  differential. 
But  if  the  lines  of  motion  in  the  first  case  be  right  lines,  they 
will  not  be  so  in  the  second,  unless  the  velocity  at  each  point 

a  x 

of  the  same  line  be  the  same.     If,  for  instance,  u  —  —* 5. 

xl+yl 

v  =     Q  •y--a)  10  =  0,  and  if  we  now  suppose  the  whole  mass  of 

x  +  y 
fluid  to  be  moving  besides  with  a  uniform  velocity  parallel  to  x, 
the  lines  of  motion  and  of  direction  will  both  be  right  lines  in 
the  first  case,  but  neither  of  them  will  be  right  lines  in  the 
second. 

Professor  Challis  objects  to  the  case  of  motion  to  which  he 
alludes,  where  u  =  a  x,  v  =  —  ay,  w  =  0,  by  saying  that 
the  arbitrary  quantities  introduced  in  the  process  of  inte- 
gration cannot  be  satisfied,  unless  the  fluid  be  in  confined 
spaces  or  narrow  canals ;  that  is  in  indefinitely  narrow  canals, 
as  his  reasoning  which  follows  shows  to  be  the  meaning.  It 
will  appear  however  from  the  following  reasoning  that  the 
canals  need  not  be  narrow. 

Conceive  a  mass  of  incompressible  fluid  to  be  at  rest,bounded 
by  material  parallel  planes,  and  by  cylindrical  surfaces  whose 
bases  are  part  of  a  branch  of  a  rectangular  hyperbola,  its 
asymptotes  (which  I  shall  take  for  the  axes  of  x  and  y),  and 
two  lines  perpendicular  to  them.  Of  the  two  planes  whose 
bases  are  the  two  latter  lines,  conceive  one,  whose  equation 
is  y  =  yv  to  be  made  to  move  with  a  velocity  — f{t)yx  par- 
allel to  y,  and  the  other,  whose  equation  is  x  m  xv  with  a 
velocity  f(t)  xy  parallel  to  x,  and  conceive  the  planes  to  con- 
tract or  expand,  so  as  always  to  reach  from  the  hyperbola  to 
an  asymptote.  Then  the  motion  is  determined  by  the  equa- 
tions of  motion,  the  equation  of  continuity,  and  the  condition 
that  the  particles  in  contact  with  a  surface,  whether  fixed  or 
moveable,  neither  penetrate  into,  nor  separate  from  it.  Since 
the  motion  is  determinate,  and  these  are  the  only  conditions 
to  be  satisfied,  any  values  of  w,  v,  w  and  p  which  satisfy  them, 
will  be  the  true  values.  Such  values  will  be  found  to  be 

u=f{t)x,   v=-f{t)y,  wsO,  £  =v|/(/)-M"2  +  ^2). 


300  The  Rev.  H.  Moseley  on  Conchyliometry. 

The  function  f  is  arbitrary,  and  may  be  discontinuous.  It  is 
supposed  to  be  nothing  at  first.  If  it  suddenly  acquires  a 
finite  value,  the  motion  will  begin  with  impact.  It  will  be 
easily  seen  that  the  equations  of  impulsive  motion,  and  the 
conditions  with  respect  to  the  surfaces,  will  be  satisfied  by 
the  above  values  of  u  and  v,  and  the  value  of  the  impulsive 

pressure  C 1-  (w2  +  r>9). 

S6 


LII.  On  Conchyliometry.  By  the  Rev.  H.  Moseley,  M.A., 
F.R.S.,  Professor  of  Natural  Philosophy  and  Astronomy  in 
King's  College,  London. 

To  the  Editors  of  the  Philosophical  Magazine  and  Journal. 
Gentlemen, 
TN  a  paper  printed  in  the  Transactions  of  the  Royal  Society 
■*■  (1838,  part  ii.*)  I  have  investigated  certain  properties  of 
the  spiral  curves  traced  upon  the  surfaces  of  shells  (concho- 
spiralsf)  common  to  them  and  to  the  well-known  logarithmic 
spiral. 

The  results  deduced  from  my  admeasurements  have  since 
been  confirmed  by  those  of  Professor  Naumann  of  Freiberg 
(PoggendorfF's  Journal,  1840),  who  has  developed,  by  an  in- 
dependent investigation,  several  new  properties  of  these  curves, 
and  determined  with  his  accustomed  accuracy,  in  respect  to 
an  extensive  series  of  Conchylia,  the  particular  value  of  the 
constant  angle  according  to  which  each  traces  its  concho- 
spiral. 

With  a  view  to  a  further  development  of  the  geometrical 
properties  of  shells,  I  have  in  my  paper,  above  referred  to, 
investigated  certain  formulae  representing  the  equation  to  the 
concho-spiral,  the  volume  of  a  conchoidal  solid,  the  position 
of  its  centre  of  gravity,  and  the  area  of  a  conchoidal  surface. 
In  the  inclosed  paper  I  have  continued  these  researches  in 
respect  to  concho-spirals  and  conchoidal  surfaces,  and  in 
some  particulars  corrected  them. 

King's  College,  London,  Yours,  &C, 

July  20, 1842.  Henry  Moseley. 

I.  The  Polar  Equation  to  a  Concho-spiral. 
Let  a  logarithmic  spiral,  whose  polar  equation  is  R  =  R0 
ge  cot  A^  ke  conceived  to  be  wrapped  upon  a  cone  the  angle  at 

[*  An  abstract  of  Prof.  Moseley's  paper  here  referred  to  was  given  in 
Phil.  Mag.  S.  3.  vol.  xiii.p.  464.] 
f  I  have  adopted  the  nomenclature  of  Prof.  Naumann. 


The  Rev.  H.  Moseley  on  Conchyliometry .  301 

whose  apex  is  2 ,  the  pole  of  the  spiral  coinciding  with  the  apex 

of  the  cone.  The  circular  arc  8,  whose  radius  is  unity  when 
developed,  will  when  wrapped  upon  the  cone,  become  a  cir- 
cular arc  0,  whose  radius  is  sin  i, 

.*.  8  =  0  sin  t, 
whence  it  follows  that  R  representing  the  distance  of  any 
point  in  the  spiral  from  the  apex  of  the  cone,  and  0  the  angle 
included  between  two  planes,  intersecting  in  the  axis  of  the 
cone,  one  passing  through  that  point  of  the  spiral,  and  the 
other  through  the  point  where  R  =  R0,  we  have 
R  =  R0  s<>sin'cotA. 
Let  Ri  R2  R3,  &c.  be  distances  from  the  apex  of  the  cone 
of  points  of  the  spiral  in  the  same  straight  line  passing  through 
the  apex, 


.-.  Rx  = 

R0 

e  6  sin  /  cot  A 

R2  = 

R0 

s  (4+2  ->t)  sin  i  cot  A 

R3  = 

R0 

g  (4+4  <r)  sin  / 

cot  A 

(*V 

-Ri) 

=  R0(s2srsi2LL 

cot  A  jN  gtfsin 

i  cot  A 

(R3- 

-R2) 

=   R0  (s  2*  sinj_cot  A  j  j  ei  s;n 

/  cot  A  ; 

g  2  <r  sin 

<  cot  A 

.-. 

Q  -  R*~ 
R2- 

-R2 

__    .2*  sin  / 

cot  A 
> 

Q  representing  the  quotient  of  any  two  consecutive  distances 
between  the  whorls  measured  on  the  same  straight  line  passing 
through  the  apex. 

On  the  supposition  made  therefore,  viz.  that  a  plane  lo- 
garithmic spiral  is  wrapped  upon  a  cone,  its  pole  coinciding 
with  the  apex  of  the  cone,  it  follows  that  the  distances  of  the 
successive  whorls  of  the  spiral  measured  on  the  same  straight 
line  passing  through  the  apex  of  the  cone,  are  in  geometrical 
progression  ;  and  conversely.  Now  in  shells  they  are  found, 
by  admeasurement,  thus  to  be  in  geometrical  progression. 
The  spirals  described  on  shells,  and  called  concho-spirals,  are 
therefore  such  as  would  result  from  winding  plane  logarithmic 
spirals  on  cones. 

To  determine  in  respect  to  any  shell  the  constant  angle  A 
which  the  tangent  to  its  concho-spiral  when  developed  makes 
with  its  radius  vector,  let  it  be  observed  that 
logs  Q  =  2  7T  sin  »  cot  A 

.         2  7rsin  i  ,.  . 

.•.  tan  A  =  -j p^,     (1.) 

log,  Q 

where  A  is  the  angle  required. 


S02  The  Rev.  H.  Moseley  on  Conchyliometry. 

Now  the  quotient  Q  is  the  same  for  all  the  spirals  described 
on  the  surface  of  the  same  shell  ;  if  then  we  represent 

logs  Q  , 
*        bye, 

2  7T  * 

we  have     sin  i  cot  A  =  —  ° =  c, 

2  7T 

and  R  =  n0Bc°     (2.) 

which  is  the  general  equation  to  a  concho- spiral. 

Since  each  of  the  concho-spirals  on  any  shell  must  have 
its  origin  in  a  corresponding  point  of  the  generating  curve  of 
that  shell  when  in  its  initial  position,  and  since  the  initial 
dimensions  of  the  generating  curve  of  every  such  shell  are  ex- 
ceedingly (perhaps  infinitely)  small,  it  follows  that  all  such 
spirals  have  their  origins  very  nearly  (perhaps  accurately)  in 
the  same  point,  and  therefore  that  the  conical  surfaces  on 
which  they  are  severally  described  have  their  apices  in  the 
same  point* ;  the  value  of  R0  being  the  distance  from  the  com- 
mon apex  to  that  particular  point  of  the  generating  curve,  at 
which  the  spiral  intersects  it,  in  that  position  in  which  0  is 
assumed  to  be  zero. 

II.  To  determine  the  inclination  u  of  the  tangent  at  any  point 
of  a  concho-spiral  to  a  line  drawn  from  that  point  parallel  to 
the  axis  of  the  shell. 

Let  P  Q  represent  any  portion  of  a  concho-spiral,  P  H  a 
tangent  to  it  at  P,  P  L  a  line  drawn  from  P  parallel  to  the 
axis  I  R  of  the  shell,  I  the  apex  of  the  cone  on  which  the 
concho-spiral  is  described.     Join  I  P,  then  is  I  P  H  a  con- 


stant angle  represented  by  A,  and  H  P  L  (represented  by  «) 
is  the  angle  required. 

Describe  a  sphere  with  radius  unity  from  the  centre  P,  and 
let  a  ?,  a  b,  b  e  be  the  intersection  of  the  planes  I  P  L,  I  P  H, 
L  P  H  with  its  surface.     The  spherical  angle  bae  is  a  right 

*  It  is  a  law  common  to  all  surfaces  of  revolution  whose  generating 
curves  varying  their  dimensions  remain  always  geometrically  similar,  that 
the  spiral  lines  described  by  given  points  in  these  curves  lie  all  on  the  sur- 
faces of  cones  having  a  common  apex. 


The  Rev.  H.  Moseley  on  Conchyliometry.  303 

angle,  since  the  plane  I  P  H  is  a  tangent  to  the  cone,  and 
IPL  passes  through  its  axis, 

.•.  cos  b  e  =  cos  a  e  .  cos  a  b. 

Now£<>  =  LPH  =  «,fle=LPI  =  RIP=, 
fl6  =  IPH  =  A, 
.*.  cos  a  s=  cos  i .  cos  A     (3.) 

.*.  i  +  tan2  «  =  sec2  a  =  5 s-r 

qosz  i  cosa  A 

2  1— cos2 » cos2  A  _  sin2  A  +  sin2  <  cos2  A 

cos2 1  cos2  A  cos2  <  cos2  A 

tan2A 


cos*  * 


a  tan2 1  o  1 

+  tan2i=      -  A   .  o   +tan2t=^       3      .       +1  Uan\ 
cot2  A  sin2 »  [  cor  A  sin2 1  ^ 

Now    cot  A  sin  1  =  — Jp —  (equation  1.), 

"  =  {1+(isir§)Ttan (*J 


2* 

r.     /  2 

.•.  tan 

Similarly,  it  may  be  shown  that 
sin 


in--{l+(^.)'}*rinA (5.) 

III.  The  Area  of  a  Conclwidal  Surface. 

Let  R  P  S  represent  any  position  of  the  generating  curve, 
and  QPm  a  portion  of  one  of  the  spiral  lines  generated  by 
any  point  P  in  it.  Let  I  represent  the  apex  of  the  cone  on 
whose  surface  the  spiral   P  Q  is  described.     Join  P  I  and 


draw  P  H  a  tangent  to  the  spiral,  and  P  T  a  tangent  to  the 
generating  curve  in  P.  Imagine  a  sphere  described  with 
radius  unity  from  the  centre  P,  and  let  a b,  be,  ac  repre- 
sent the  intersections  of  the  planes  H  P  I,  H  P  T,  and  I  P  T 
with  its  surface.  Now  the  plane  H  P  I,  being  a  tangent  to 
the  cone  at  P,  is  perpendicular  to  the  plane  RIP  which  passes 
through  its  axis  I  R  S  ;  the  spherical  angle  b  a  c  is  therefore  a 
right  angle. 

Moreover,  the  angle  I  P  Q  made  by  a  tangent  to  the  spiral 
with  the  line  I  P  drawn  from  the  summit  of  the  cone  is,  in  the 


304<  The  Rev.  H.  Moseley  on  Conchyliometry. 

case  of  shells,  a  constant  angle,  represented  by  A,  and  the 
angle  P  I  R,  being  half  the  angle  at  the  apex  of  the  cone,  is 
also  a  constant  angle  in  respect  to  that  spiral,  represented  by  *. 
The  angle  P  T  R  made  by  a  tangent  to  the  generating  curve 
at  P  with  the  axis  of  the  cone  is  constant  for  the  different 
positions  of  the  same  point  P  on  the  generating  curve,  as  the 
curve  varies  its  -position  by  the  variation  of  0,  but  variable  for 
different  points  on  the  generating  curve,  in  any  given  position 
of  that  curve ;  let  it  be  represented  by  <$>.  <p  is  then  a  function 
of  the  coordinates  of  the  point  P  in  any  given  position  of  the 
curve,  and  is  wholly  independent  of  the  angle  0  which  deter- 
mines the  position  of  the  generating  curve. 

Now  in  the  right-angled  spherical  triangle  a  be, 
cos  b  c  =  cos  a  b  .  cos  a  c} 
or  cos  H  P  T  =  cos  H  P  I .  cos  I  P  T, 

but  IPT  =  PTR-RIP  =  $-,, 

cos  H  P  T  =  cos  A  .  cos  (<$>  — •  i) 

.*.  sin  H  P  T  =  V  1  —  cos2  A  .  cos2  (<p— »). 

Let  R'  V  S'  be  a  position  of  the  generating  curve  exceed- 
ingly near  to  the  former,  and  V  n  a  portion  of  another  spiral 
line  on  the  surface  of  the  shell  exceedingly  near  to  the  spiral 
QPw.  Then  may  the  elementary  surface  P  V  be  considered 
(in  the  limit)  an  oblique  parallelogram,  whose  sides  are 
straight  lines,  and  whose  area  is  therefore  represented  by 

P  m  .  P  n  .  sin  m  P  n. 

Let  P  n  be  represented  by  A  s,  s  representing  the  arc  R  P 
of  the  generating  curve ;  and  P  m  by  A  S,  S  representing 
the  length  of  the  spiral  measured  from  the  point  where 
0  =  0;  and  let  it  be  observed  that  sin  m  P  n  —  sin  H  P  T 


=  V  1—  cos2  A  cos2  (<J>— i) 
.-.  area  P  V  =    v'  1-cos2  A  cos2  (<J>  -  i)  .  As.AS. 

Now  the  whole  surface  is  made  up  of  elements  similar  to  P  V* 
therefore  passing  to  the  limit  and  integrating, 

whole  surface      =Jj  \/ x  _ coss A C0g2  ^ _ ^ # dsdS 

-  /TV  1  -cos2A  cos2  ($-i) .  ~  dQ  ds, (6.) 

which  is  a  general  expression  for  the  area  of  a  surface  of  re- 
volution, whose  generating  curve,  varying  its  dimensions, 
remains  always  similar  to  itself. 

In  the  case  of  shells,  if  the  surface  of  the  cone  on  which 


The  Rev.  H.  Moseley  on  Conchyliometry.  305 

the  spiral  P  Q  is  described  be  developed,  this  spiral  will  be- 
come a  plane  logarithmic  spiral,  whose  polar  equation  has 
been  shown  to  be 

R  =  R0  g  e  cot  A  where  0  —  0  sin  i 


Now  sin  i  cot  A  =  — -^ — •=  c 

2  7T 

dS         dS         dO  t>     •  a    ci 

.'.  — — -  ss  — —  .  — - —  =   Rn  sin  »  cosec  Aec 
dd         de         dS  ° 

.\  con.  surf.  =  /  /  R0  sin  i  cosec  A  { 1  —  cos2  A  cos2  ($  —  «)}  ^o6edHs. 

Now  sin  t  cosec  A  { 1  —  cos2 A  cos2  ( <p  —  i) }  I  =  {  sin2  *  cosec2  A 
—cot2  A  sin2  <  cos2  (<p  —  i)  }*  =  {sin2  <  +  sin2 »  cot2  A 
-cot2Asin2*cos*  (<p  — i)}*={sin2i  +  sin2»cot2  A  sin2  ($  —  »)}* 
=  {sin2»  +  c2sin2  ($  — i)}* 
.-.  con.  surf.  =/TRo  {sin2*  +  c2  sin2  ($-*)}  V'rffl  ds. 

Let  s0  be  taken  to  represent  the  value  of  s  when  0  =  0, 

•  •  *  —  *o  •        ' 

differentiating  this  value  of  s  in  respect  to  a  given  position  of  the 

ds       ct 
generating  curve  -% —  =  e 
d  s0 

.-.conch.  surf.  =y^0«f  sin2, +  c2  sin2  (<j>-,)"|  V'<Z0~  dsc 

=  /7X  {sin2  ■  + c2  sin2  (♦  -  oV e2  c  '  <*  s .  rf50. 

Or  integrating  in  respect  to  0  and  observing  that  R0,  i,  <p  do 
not  involve  0, 

conch,  surface  =  — —  (s  —  1  )  /  R0]  sin2  « +  c2  sin2(4>  — »)  r  d  s0 

(7.) 

where  the  integral  /  R0-<  sin2  i  +  c2  sin2  (<p — »)  >  rfs0  re- 
presents a  constant  determined  by  the  geometrical  form  of  the 
generating  curve,  and  its  dimensions  when  0=0. 

[The  general  form  of  the  expression  agrees  with  that  given 
in  equation  15,  p.  368  of  a  paper  on  the  geometrical  pro- 
perties of  turbinated  and  discoid  Shells  in  the  Phil.  Trans., 
part  ii.  1838.] 

Phil.  Mas.  S.  3.  Vol.  21.  No.  138.  Oct.  1842.  X 


[  306  ] 
LI  1 1.    Proceedings  qf  Learned  Societies. 

GEOLOGICAL  SOCIETY. 
[Continued  from  p.  150. J 
Nov.  17,   A    LETTER  addressed  to  Dr.  Fitton,  by  Mr.  Lyell,  and 
1841.    **-  dated  Boston  the  15th  of  October,  1841,  was  read. 
Mr.  Lyell's  attention,  between  the  period  of  his  arrival  in  the 
United  States  and  the  date  of  his  letter,  had  been  principally  devoted 
to  the  grand  succession   of  Silurian,  Devonian,  and  Carboniferous 
strata  in  the  state  of  New  York  and  on  the  borders  of  Pennsylvania, 
having  been  accompanied  during  a  portion  of  his  tour  by  the  States' 
Geologist,  Mr.  J.  Hall ;  but  he  had  also  visited,  in  company  with  that 
gentleman,  the  Falls  of  Niagara  and  the  adjacent  district,  and  he  states, 
that  he  purposes  to  communicate  a  paper  on  the  phenomena  of  the 
recession,  drawn  from  new  arguments,  founded  on  the  position  of  a 
fluviatile  deposit  below  the  Cataract.     He  expresses  his  intention  of 
also  communicating  a  notice  of  five  localities  of  Mastodon  bones  which 
he  had  visited,  digging  up  some  remains  himself,  and  collecting  the 
accompanying  shells,  which  he  says,  seem  to  have  been  neglected. 
He  had  likewise  examined,  accompanied  by  Prof.  Silliman  and  his  son, 
the  new  red,  with  intrusive  trap,  in  Connecticut ;  and,  assisted  by 
Mr.  Conrad,  he  had  collected  fossils  in  every  member  of  the  cretaceous 
system  in  New  Jersey  *.    The  principal  object,  however,  of  the  present 
communication  is,  to  point  out  the  extension  to  the  United  States  of 
Mr.  Logan's  generalizations  on  the  beds  of  fire-clay  containing  Stig- 
maria,  formerly  laid  before  the  Society  in  a  paper  on  the  coal-field 
of  South  Walesf.     Mr.  Lyell  had  met  Mr.  Logan  at  New  York,  pre- 
viously to  that  gentleman's  visit  to  the  anthracite  coal-field  of  Penn- 
sylvania, and  he  adverts  to  the  delight  which  Mr.  Logan  must  have 
felt  in  witnessing  the  occurrence  of  beds  of  Stigmaria  fire-clay  to  an 
extent  far  exceeding  what  could  have  been  expected.     On  the  con- 
fines of  the  states  of  New  York  and  Pennsylvania,  Mr.  Lyell  found 
remains  of  Holoptychius  and  other  fishes  in  the  old  red  sandstone, 
and  at  the  bottom  of  the  overlying  coal  series  a  thick  quartzose 
conglomerate ;  and  he  says  that  the  coal-measures,  with  their  im- 
bedded plants,  bear  an  exact  analogy  to  British  coal-measures,  both 
in  detail  and  as  a  whole.     In  investigating  the  coal  district  of  Bloss- 
berg,  Mr.  Lyell  had  for  a  guide  Dr.  Saynisch,  president  of  the  mines. 
The  first  point  which  they  examined  presented  three  seams  of  bitu- 
minous coal  resting  on  fire-clay  containing  Stigmariae,  with  the  leaves 
attached  to  the  stems,  and  extending  in  all  directions  through  the 
clay ;  and  they  observed,  in  a  gallery  lighted  on  purpose,  that  the 
stems  seen  in  situ  were  very  nearly  all  parallel  to  the  planes  of  stra- 

*  Mr.  Lyell  mentions  incidentally  having  observed  between  Easton  and 
Trenton,  on  the  Delaware,  and  in  40°  of  north  latitude,  that  all  the  trees 
were  barked  on  one  side,  at  the  height  of  twenty-two  feet  above  the  present 
level  of  the  river,  owing  to  a  freshet  and  stoppage  by  ice  in  the  spring  of  1841. 
The  stuccoed  parts  of  the  houses  were  also  strangely  scraped ;  and  in  one 
place  the  canal,  the  towing-path  of  which  is  twenty-two  feet  above  the  river, 
was  so  filled  with  gravel  that  carriages  did  not  cross  by  the  bridges. 

[f  See  Phil.  Mag.,  S.  .'5.,  vol.  xviii.  p.  217;  vol.  xx.  p.  430.] 


Geological  Society.  307 

tification,  only  one  being  in  an  oblique  position.  Every  stratum 
underlying  a  coal-seam  examined  by  Mr.  Lyell,  presented  the  same 
phenomena,  except  one,  and  in  that  case  the  bed  was  so  sandy  that 
it  could  not  be  considered  as  a  fire-clay.  The  thickness  of  these 
Stigmaria  deposits  varied  from  one  foot  to  six  feet.  The  roof  of  the 
Blossberg  coal-seams  consists  usually  of  bituminous  slates,  but  occa- 
sionally of  very  micaceous  grit,  and  it  contains  great  varieties  of 
ferns,  as  well  as  other  plants,  agreeing,  generically  at  least,  with 
those  common  in  the  British  coal-measures. 

Mr.  Lyell  next  examined  the  anthracitic  coal-district  at  Pottsville, 
on  the  Schuylkill,  in  the  southern  part  of  the  Alleghanies.  This 
district  had  been  examined  and  described,  as  well  as  modelled,  by 
Mr.  R.  C.  Taylor,  and  the  model  had  been  inspected  by  Mr.  Lyell 
previously  to  his  visit.  The  whole  of  Pennsylvania  has  been  mapped 
by  Prof.  H.  D.  Rogers,  by  direction  of  the  State  Legislature.  Mr. 
Lyell  refers  to  this  survey,  and  he  states  that,  by  consulting  Prof. 
Rogers's  map,  it  will  be  found  that  the  Alleghanies,  or  more  properly 
the  Appalachians,  which,  viewed  geologically,  are  120  miles  broad, 
consist  of  twelve  or  more  great  parallel  ridges,  or  anticlinal  and  syn- 
clinal flexures,  having  a  general  north-north-east  and  south-south- 
west strike,  but  in  Pennsylvania  a  nearly  east  and  west  strike  prevails. 
The  strata  are  most  tilted  on  the  southern  border  of  the  chain,  where 
their  position  is  often  inverted,  and  the  folds  become  less  and  less 
towards  the  central  ridges  and  troughs,  which  again  increase  in 
breadth  the  more  northward  their  position,  till  at  last  the  beds  are 
almost  horizontal.  The  oldest  formations  also  are  chiefly  exposed 
in  the  most  southern  or  disturbed  regions,  where  syenite  and  other 
plutonic  rocks  are  intruded  into  the  lower  part  of  the  Silurian  series. 
It  has  long  been  observed,  that  the  anthracitic  coal  is  confined  to  the 
southern  or  Atlantic  side  of  this  assemblage  of  small  parallel  chains, 
and  that  the  bituminous  occurs  in  the  more  inland  or  less  disturbed 
region  ;  the  conclusion,  therefore,  Mr.  Lyell  states,  seems  inevitable, 
that  the  change  in  the  condition  of  the  coal  was  a  concomitant  of  the 
folding  and  upheaval  of  the  rocks.  The  conversion,  moreover,  is 
most  complete  where  the  beds  have  been  most  disturbed ;  and  there 
are  tracts  in  Pennsylvania  and  Virginia,  near  the  centre  of  the  chain, 
where  the  coal  is  in  a  semi-bituminous  state.  Chemical  analysis, 
likewise,  has  shown  that  a  gradation  from  the  most  bituminous  to 
the  most  anthracitic  coal  may  be  found  in  crossing  the  chain  from 
north  to  south*.  The  associated  shales,  &c,  of  the  disturbed  regions 
exhibit  no  alterations. 

It  has  also  been  supposed  that  the  anthracite  belonged  to  the  trans- 
ition, and  the  bituminous  coal  to  the  secondary  period ;  but  this  be- 
lief, Mr.  Lyell  says,  has  been  gradually  abandoned,  as  the  knowledge 
of  the  geological  position  and  the  fossil  plants  of  the  coal- districts 
have  become  better  known.  Both  the  anthracitic  and  the  bituminous 
coal  overlie  the  old  red  sandstone,  and  contain  the  same  ferns,  Si- 
gillarise,  Stigmariae,  Asterophyllites,  &c. ;  and  they  are  as  abundant 
and  perfect  in  the  anthracite  as  in  the  bituminous  coal. 

*  See  papers  by  Prof.  fj.  D.  Rogers,  Dr.  Silliman,  &c. 
X2 


308  Geological  Society : — Mr.  Lyell  on  the 

At  the  first  point  where  Mr.  Lyell,  accompanied  by  Prof.  Rogers, 
examined  the  Pottsville  coal-measures,  the  strata  are  nearly  vertical, 
being  cut  off  by  a  great  fault  from  the  less  inclined  beds  which 
form  the  northern  prolongation  of  the  measures.  They  present 
thirteen  beds  of  anthracite,  the  lowest  of  which  alternate  with 
the  uppermost  strata  of  the  coarse  underlying  conglomerate.  The 
southern  wall  of  an  excavation  from  which  the  coal  had  been  re- 
moved, and  which  wall  occupied  the  place  of  the  underclay,  pre- 
sented impressions  of  the  stems  and  leaves  of  Stigmaria;  and  on 
the  more  solid  and  slaty  beds  of  the  opposite  wall,  or  original  roof, 
there  were  leaves  of  Pecopteris,  reed-like  impressions,  and  Calamites. 
In  the  slightly  inclined  northern  continuation  of  the  coal-measures, 
Mr.  Lyell  observed  in  the  Peachmount  vein,  three  miles  north-east 
of  Pottsville,  a  bed  of  anthracite  eight  feet  thick,  overlaid  by  the 
usual  roof  of  grey  grit,  and  underlaid  by  blue  clay  or  shale  with 
Stigmaria?.  Impressions  of  ferns  were  likewise  noticed  in  the  coal 
itself.  Only  one  instance  was  met  with  in  the  Pottsville  coal-district, 
by  Mr.  Lyell  and  Prof.  Rogers,  of  a  Stigmaria,  placed  at  right  angles 
to  the  plane  of  stratification. 

The  Pottsville,  or  southern  anthracitic  coal-field  of  Pennsylvania 
was  illustrated  by  a  section  resulting  from  the  former  labours  of 
Prof.  Rogers,  under  whose  guidance  Mr.  Lyell  examined  the  coun- 
try. The  following  remarks  may  explain  the  general  structure  of 
the  country  ;  the  names  applied  to  the  formations  are  not,  however, 
those  previously  employed  by  the  American  geologists,  but  those 
suggested  by  Mr.  Lyell,  in  conformity  with  the  conclusions  at  which 
he  arrived  after  his  tour  in  New  York,  and  a  comparison  of  the  strata  of 
that  state  with  their  British  equivalents.  The  contrast  between  the 
relative  importance  of  most  of  the  Silurian  and  Devonian  groups  in 
Pennsylvania  and  in  New  York,  Mr.  Lyell  states,  is  very  great,  arising 
from  a  larger  portion  of  sandstones  and  grits  in  the  Pennsylvanian 
rocks.  The  section  extends  from  north  of  Pottsville  to  the  country 
ranging  immediately  south  of  Orwigsburg.  To  the  south  of  the 
vertical  coal-measures  and  the  subjacent  conglomerate  there  are 
displayed  successively — 1st,  a  vast  series,  composed  of  red  shales 
3000  feet  thick,  of  grey  sandstone  2400  feet  thick,  and  of  red  sand- 
stone 6000  feet  thick,  the  whole  being  considered  by  Mr.  Lyell  as 
portions  of  the  old  red  sandstone ;  and  2nd,  of  olive-coloured  shale 
containing  Devonian  fossils.  The  dip  of  the  strata  is  either  nearly 
vertical  or  inverted.  Still  further  south,  and  a  short  distance  north 
of  Orwigsburg,  the  olive-coloured  shales  are  succeeded  by  very  highly 
inclined  or  inverted  beds  of  upper  Silurian  rocks  flanking  a  protruded 
band  of  lower  Silurian  strata ;  and  lastly,  on  the  southern  confines 
of  the  section  is  a  trough  of  the  Devonian  olive- coloured  shales 
resting  on  the  upper  Silurian  strata. 

Beautiful  exhibitions  of  the  underclay  with  its  associated  plant, 
and  of  the  overlying  roof  with  its  distinct  remains,  were  observed  by 
Mr.  Lyell  and  Prof.  Rogers  at  Tamaqua,  in  the  southern  coal-field. 
The  thinning  out  of  the  grits  and  conglomerates  of  the  west  causes 
the  beds  of  anthracite  to  be  brought  more  nearly  together  in  this 


Stigmaria-Clay  in  the  Coal-Jield  of  Pennsylvania.      309 

district ;  and  Mr.  Lyell  says,  the  decrease  in  the  thickness  of  the  in- 
tervening strata  prepares  the  observer  for  the  union  of  several  of  the 
seams  still  farther  east,  and  for  the  enormous  thickness  of  the  anthra- 
cite at  various  places  near  the  village  of  Mauch  Chunk,  or  Bear 
Mount,  particularly  at  the  well-known  Lehigh-Summit  Mines.  At 
this  point  a  mass  of  anthracite  forty  feet  thick,  deducting  three  in- 
tercalated fire-clays  and  a  fine  thin  vein  of  impure  coal,  is  quarried 
in  open  day,  a  covering  of  forty  feet  of  sandstone  being  entirely  re- 
moved. In  the  south  mine,  where  there  is  a  sharp  anticlinal  fold  in 
the  coal,  the  Stigmaria-clay,  four  feet  thick,  was  well  seen,  with 
nearly  forty  feet  of  coal  above  it  and  four  below.  In  the  Great  mine 
Mr.  Lyell  observed  the  following  section  : — 

Top,  yellow  quartzose  grit. 

Coal,  two  or  three  inches  of  the  uppermost  part  of  the 
bed  being  in  the  state  of  dust,  as  if  they  had  been 
crushed  or  rubbed  by  the  yellow  quartzose  grit 5  feet. 

Blue  fire-clay  with  Stigmariae 15  inches. 

Coal,  including  two  or  three  seams  of  an  impure  slaty 

nature 25  feet. 

Blue  fire-clay  with  Stigmariae 2  feet. 

Coal,  with  an  intervening  layer  of  hard,  bituminous  slate     8  feet. 

The  anthracite,  as  in  other  parts  of  these  coal-measures,  often 
exhibits  a  texture  exactly  like  that  of  charcoal ;  and  frequently  im- 
pressions of  striated  leaves,  exactly  resembling,  as  pointed  out  by 
Prof.  Rogers,  those  of  liliaceous  plants,  particularly  the  iris. 

Mr.  Lyell,  accompanied  by  Prof.  Rogers,  afterwards  examined  the 
Room  Run  mines,  on  the  Nesquahoning,  where  he  saw  a  splendid 
exhibition  of  Stigmariae  in  a  bottom  clay,  one  stem,  about  three 
inches  in  diameter,  being  no  less  than  thirty-five  feet  in  length.  In 
the  roof  of  slaty  sandstone  were  impressions  of  Pecopteris,  Glos- 
sopteris,  and  other  ferns. 

At  Beaver  Meadow,  or  the  middle  coal-field,  a  bed  of  anthracite  is 
overlaid  as  well  as  underlaid  by  Stigmaria  blue  clay ;  the  upper  fire- 
clay, however,  soon  thins  out,  and  is  replaced  by  sandstone.  No  coal 
rested  upon  it,  but  Mr.  Lyell  observes  that  the  carpeting  of  coal 
may  not  be  always  large  enough  to  cover  the  flooring  of  fire-clay,  or 
some  change  of  circumstances  or  denudation  may  have  interfered 
with  the  usual  mode  of  deposition.  Upon  the  whole,  Mr.  Lyell 
says,  the  accumulation  of  mud  and  Stigmariae  was,  in  Pennsyl- 
vania as  in  South  Wales,  the  invariable  forerunner  of  the  circum- 
stances attending  the  production  of  the  coal-seams.  The  two  ex- 
treme points  at  which  he  observed  the  Stigmaria-clay,  Blossberg  and 
Pottsville,  are  about  120  miles  apart  in  a  straight  line,  and  the  ana- 
logy of  all  the  phaenomena  at  those  places,  and  still  more  on  both 
sides  of  the  Atlantic,  is,  he  says,  truly  astonishing.  In  conclusion, 
Mr.  Lyell  states,  that  he  had  just  received  a  letter  from  Mr.  Logan, 
announcing  the  existence  of  the  bottom  clay,  with  Stigmariae,  in 
Nova  Scotia ;  and  that  Mr.  Logan  had  visited  Mauch  Chunk. 


310  London  Electrical  Society. 

LONDON    ELECTRICAL   SOCIETY. 

[Continued  from  p.  64.] 
July  19*. — The  Society  assembled  for  the  first  time  in  its  new 
apartments  in  Cavendish  Square.  The  following  papers  were  read  : — 

1 .  "  On  the  Solution  of  Gold  in  Muriatic  Acid  by  Voltaic  Agency." 
By  H.  Prater,  Esq.,  Memb. 

2.  "  On  the  Action  of  Lightning  Conductors."  By  Mr.  Charles 
V.  Walker,  Hon.  Sec. 

Having  introduced  the  subject  by  referring  to  his  observations  on  the 
lightning-flash  at  Brixton  Church  (vide  Phil.  Mag.  for  July,  p.  63.), 
the  author  states  that  a  series  of  recent  experiments  have  rather 
tended  to  confirm  than  change  his  opinion  upon  the  phenomena 
termed  often  "lateral  discharge;"  and  that  his  present  object  is  to 
direct  the  attention  of  the  Society  to  certain  facts,  which  have  not 
been  so  prominently  regarded  as  their  nature  demands ;  and  here 
especial  allusion  is  made  to  the  Leyden  discharge.  That  this  dis- 
charge is  often  employed  in  illustrating  the  action  of  lightning  is 
manifest  to  all  who  have  paid  any  attention  to  the  matter,  and  that 
a  large  portion  of  the  experiments,  which  have  given  rise  to  so  much 
difference  of  opinion,  are  the  effects  of  Leyden  discharges,  is  like- 
wise well  known. 

Mr.  Walker  commences  by  endeavouring  to  show  the  difference 
between  such  discharge  and  a  flash  of  lightning  :  he  states,  that  sup- 
posing a  cloud  to  resemble  one  coating  of  a  jar,  the  air  to  corre- 
spond with  the  glass,  and  the  earth  with  the  other  coating,  the 
discharge  of  that  cloud  is  directly  between  the  coatings,  viz.  through 
the  insulator ;  and  he  then  shows  that  a  Leyden  discharge  only  re- 
sembles this,  when  it  is  of  force  sufficient  to  perforate  the  glass.  He 
explains  that  the  regular  discharge  is  operated  upon  by  two  forces 
acting  counter  to  each  other ;  the  one  directly  between  the  two 
coatings  in  direction  a,  the  other  between  the  discharging  balls  in 
a  direction  b  ;  and  that  the  length  of  shock,  or  as  it  is  termed  striking 
distance,  is  the  difference  between  these  forces  :  when  a  —  b  represent 
the  resultant,  the  glass  is  perforated  ;  when  b— a  is  the  equivalent, 
the  regular  discharge  occurs.  That  this  explanation  is  not  imaginary, 
is  shown  by  comparing  the  striking  distance  of  the  Leyden  discharge 
with  that  from  the  prime  conductor.  With  the  Polytechnic  battery, 
containing  70  feet  of  coated  glass,  the  distance  is  about  one  inch, 
while  from  the  large  conductor  of  the  machine  sparks  upwards  of 
two  feet  long  will  appear.  He  then  calls  into  requisition  the  ocular 
illustration  of  difference  ;  when  one  spark  is  direct  and  compact,  the 
other  is  long  and  zigzag ;  and  this  leads  him  to  point  out  the  re- 
semblance between  lightning  flashes  and  sparks  from  the  conduct- 
or ;  not  merely  in  their  visible  and  accidental  characters,  but  in 
their  passing  just  as  lightning  does,  directly  from  a  charged  body  to- 
wards the  earth  in  the  direction  of  least  resistance.     Having  shown 

*  The  papers  read  before  the  Society  in  April,  omitted  to  be  noticed  in 
our  last,  will  be  found  in  the  Proceedings,  Part  V. 


Mr.  C.  V.  Walker  on  Lightning  Conductors.         311 

his  reasons  for  excluding  Leyden  jars  from  this  inquiry,  and  glanced 
at  the  importance  of  establishing  such  a  position,  he  proceeds  to 
throw  sparks  from  the  machine  into  wires  arranged  to  represent 
lightning  rods,  and  makes  his  observations  upon  the  effects  produced 
by  these  wires.  Some  of  them  pass  perpendicularly  between  the  con- 
ductor and  the  earth,  others  are  led  off  horizontally  :  all  give  rises  to 
the  said  "  lateral  spark."  The  next  point  was  to  show  that  these  wires 
did  resemble  lightning-rods ;  and  for  this  purpose  an  arrangement 
was  made,  as  closely  resembling  nature  as  possible :  a  brass  rod, 
terminating  in  a  ball,  was  erected  beneath  a  similar  ball  proceeding 
from  the  prime  conductor  of  the  machine,  and  sparks  were  passed 
between  the  two :  beside  the  rod  was  held  a  smaller  and  shorter 
one,  also  terminating  in  a  ball ;  the  larger  rod  was  screwed  into  a 
brass  disc,  the  smaller  rested  on  the  floor ;  each  was  separately  con- 
nected with  a  good  discharging  train.  All  things  being  in  order, 
sparks  were  thrown  from  the  prime  conductor,  and  "  lateral  sparks" 
passed  in  abundance  between  the  rods :  and  if  this  represented  a 
lightning  rod,  it  appeared  lawful  to  infer  that  in  every  other  arrange- 
ment when  sparks  were  obtained,  they  proceeded  from  the  wires 
being  a  representation  of  a  lightning  rod.  Without  entering  into 
the  various  experiments,  all  tending  to  develope  the  same  truth,  we 
come  to  show  the  explanation  this  last  affords  of  the  action  of  an 
elevated  rod  between  two  metallic  discs. 

It  is  well  known  that  such  a  rod  will  not  give  off  sparks  to  vicinal 
bodies  ;  but  Mr.  Walker  is  of  opinion  that  this  want  of  the  la- 
teral discharge  is  due  to  the  fact  that  the  vicinal  body  rests  on  the 
lower  disc,  and  is  thus  a  direct  metallic  connexion  with  the  main  rod ; 
in  proof  of  which  he  shows,  that  the  sparks  in  his  experiment  just 
noticed,  ceases  the  instant  the  end  of  the  lower  rod  touches  the 
disc;  and  thus  too  are  confirmed  the  principles  described  in  his 
former  paper,  by  which  the  safety  of  lightning  rods  is  ensured  by 
establishing  such  contact. 

3.  "  On  a  new  form  of  Battery,  particularly  adapted  to  Blasting 
Rocks,"  &c.     By  Martyn  Roberts,  Esq.,  F.R.S.  Ed.,  Memb. 

This  battery  consists  of  alternate  and  parallel  plates  of  iron  and 
zinc,  and  is  excited  by  sulphuric  acid  1  + ,  water  30  :  the  plates  are 
supported  in  a  frame,  by  which  they  can  readily  be  immersed  in  the 
trough  of  liquid  (which  may  be  of  wood  luted  with  white  lead),  and 
be  removed  at  the  termination  of  the  experiment.  The  peculiar 
features  of  this  battery  in  contradistinction  to  others,  are  the  modes 
of  connecting  the  plates.  If  we  consider  the  figures  1,  2,  3,  4,  &c. 
to  represent  the  zinc  plates,  and  the  letters  a,  b,  c,  d,  &c.  the  iron, 
a  and  b  must  be  first  connected  ;  then  1  and  c,  2  and  d,  3  and  e,  and 
so  on,  by  which  means  both  sides  of  each  plate  are  brought  into  re- 
quisition, and  no  counter  currents  reduce  the  action.  Mr.  Roberts 
recommends  a  series  of  twenty  for  blasting,  and  says  that  they  may 
be  comprised  within  a  space  of  eight  inches. 

4.  Electro-Meteorological  Register  for  June,  by  W.  H.  Weekes, 
Esq.,  Memb. 

Aug.  16.— A  Letter  from  Walter  Hawkins,  Esq.,  F.S.A.,  F.Z.S., 


3 1 2  London  Electrical  Society. 

M  emb.  Elect.  Soc,  was  read,  in  which  allusion  was  made  to  the  recent 
serious  accidents  occasioned  by  lightning,  and  which  suggested  the 
propriety  of  the  Society's  taking  the  matter  into  consideration,  and 
publishing  some  general  directions  as  to  the  best  methods  of  pro- 
tecting churches  and  other  elevated  buildings. 

A  paper  from  a  member,  Mr.  Mackrell,  was  then  read,  detailing 
the  plan  by  which  he  had  succeeded  in  obtaining  ferric  acid  by 
electrolysis. 

A  paper  by  Henry  Letheby,  Esq.,  A.L.S.,  was  read,  detailing  the 
particulars  of  the  dissection  of  a  Gymnotus  Electricus,  and  containing 
reasons  for  believing  that  the  electric  energy  originates  in  the  brain 
and  spinal  cord.  In  reference  to  the  anatomy  of  the  fish,  the  author 
shows  that  the  electrical  organs  are  not  super- additions  of  a  peculiar 
structure,  but  are  the  result  of  an  increased  development  of  the 
aponeurotic  termuscular  septa,  which  become  so  arranged  as  to  form 
long  tubes,  running  diagonally  from  within  outwards,  so  that  the 
juxtaposition  of  these  tubes  produces  laminae  which  run  longitudinal 
to  the  animal.  The  number  of  tubes  in  the  entire  organs  is  estimated 
at  upwards  of  half  a  million.  The  organ  is  supplied  largely  by  the 
spinal  nerves  ;  the  peculiar  nerve  of  Hunter,  called  by  Mr.  Letheby 
the  posterior  or  dorsal  branch  of  the  fifth,  is  distributed  entirely  to 
the  muscles.  The  author  then  alludes  to  the  well-known  researches  of 
Williamson,  Humboldt,  Faraday,  Walsh,  Todd,  Davy,  Matteucci 
and  others,  which  have  proved  the  analogy  between  the  effects  pro- 
duced by  electrical  fishes,  and  those  developed  by  our  artificial  com- 
binations. He  then  goes  on  to  trace  the  connexion  between  these 
two  divisions  of  the  subject,  and  directs  attention  to  two  important 
facts  : — 1st,  that  the  organs  are  made  up  of  aponeurotic  septa  con- 
taining an  albuminous  gelatinous  fluid ;  and  2ndly,  that  these  are 
furnished  with  a  supply  of  nerves  far  exceeding  the  wants  of  the 
parts  for  the  purposes  of  life.  Bearing  in  mind  this  latter  fact,  and 
then  alluding  to  the  voluntary  nature  of  the  shock,  to  its  annihilation 
when  the  nerves  are  severed,  to  its  increase  when  the  nerves  are 
irritated,  he  concludes  that  the  electric  force  originates  in  the  brain 
and  spinal  cord,  and  is  concentrated  or  made  tense  in  the  organ 
itself.  He  then  gives  a  series  of  deductions  to  show  that  electricity 
and  vital  energy  are  in  a  manner  identical. 

This  paper  was  illustrated  by  an  elaborate  series  of  drawings,  and 
also  by  anatomical  preparations  of  the  organ  and  the  supplying 
nerves. 

Mr.  Weekes's  Electro-Meteorological  Report  for  July  was  then 
read,  from  which  we  gather  that  while  the  metropolis  has  been  so 
seriously  visited  by  lightning,  the  neighbourhood  of  Sandwich  has 
been  comparatively  tranquil. 

September  20.  —  The  papers  read  this  evening  were,  —  1st, 
"  Additional  Notes  on  the  Production  of  Acari,  &c.  in  close  Atmo- 
spheres, incident  to  the  operation  of  Voltaic  Currents."  By  W. 
H.  Weekes,  Esq.,  M.E.S. 

Mr.  Weekes  finds,  from  continued  observation,  that  these  insects, 
whatever  be  their  origin,  are  multiplied  by  the  ordinary  means  of 


Mr.  W.  S.  Harris  on  Lightning  Conductors.         SI 3 


© 


generation  :  he  has  observed  the  devolopment  and  departure  of  suc- 
cessive families,  and  perceives  that  the  defunct  are  devoured  by 
their  survivors.  On  the  20th  of  July,  1842,  he  terminated  the  ex- 
periment with  the  sulphate  battery,  and  was  so  unfortunate  as  not 
to  secure  a  single  specimen  of  the  insect.  With  respect  to  the 
spongy  aggregations  around  the  positive  electrode,  he  has  found 
they  are  not,  as  he  anticipated,  pure  silicon,  but  apparently  an  in- 
ferior oxide  of  that  element.  He  quotes  Dr.  Brown's  opinion,  that 
"  it  may  throw  light  on  the  doubtful  question  of  the  atomic  weight 
of  silicon." 

2nd.  "  Observations  by  W.  Snow  Harris,  Esq.,  F.R.S.,  on  a  paper 
by  Charles  V.  Walker,  Esq.,  Hon.  Sec.  L.E.S.,  entitled  '  On  the 
Action  of  Lightning  Conductors.'  " 

The  author  of  this  paper  does  not  agree  with  Mr.  Walker  in 
fearing  danger  from  the  passage  of  a  spark  from  the  lightning-rod 
to  a  vicinal  conducting  body;  and  he  thinks,  contrary  to  Mr. 
Walker,  that  the  discharge  of  a  Leyden  jar  does  resemble  a  flash 
of  lightning.  He  says,  that  "  the  lightning-rod,  so  far  from  send- 
ing out  sparks  to  neighbouring  bodies,  directs  the  passing  charge 
from  them  altogether."  He  states,  that  "  when  a  great  variety 
of  circuits  are  open  to  a  passing  discharge  of  electricity  or  light- 
ning, the  charge  will  be  likely  to  divide  on  them  all ;"  and  that 
this  is  by  no  means  a  new  fact :  this  he  alludes  to  as  the  divi- 
sion of  charge.  He  adds,  that  it  will  not  go  off  to  semi-insulated 
bodies ;  and  this  he  appears  to  consider  "  lateral  discharge."  He 
then  proceeds  to  analyse  Mr.  Walker's  experiments,  which  had  in- 
duced the  latter  gentleman  to  doubt  the  analogy  between  Leyden 
and  lightning  discharges,  and  allows  the  distinction  between  the  two 
cases,  but  not  the  difference.  He  conceives  that  the  difference  in 
the  direction  of  the  discharge  does  not  operate  against  its  special 
character.  With  respect  to  the  difference  in  the  length  of  spark, 
he  considers  this  as  "  altogether  an  affair  of  intensity,  and  of  the 
form  and  disposition  of  the  charged  conductors  ;"  and  proceeds  to 
show  varied  phenomena,  in  connection  with  varied  form  and  ar- 
rangement. He  does  not  place  so  much  reliance  as  Mr.  Walker 
upon  experiments  from  the  prime  conductor,  but  allows  certain  gene- 
ral points  in  which  it  does  resemble  a  charged  cloud.  He  then  ex- 
amines the  experiments  which  were  made  with  the  prime  conductor 
of  the  Polytechnic  Institution,  and  shows  in  what  respects  he  is 
unwilling  to  receive  them.  He  concludes  with  expressing  a  conviction 
that  there  is  no  danger  of  lightning  leaving  a  conductor  to  enter 
vicinal  bodies  ;  and  hence  considers  that  Mr.  Walker's  suggestions 
relative  to  connecting  these  bodies  with  the  main  rod,  are  not  needed. 

Mr.  Weekes's  Electro-Meteorological  Register  for  August  was 
then  laid  before  the  Society.   - 


CHEMICAL  SOCIETY. 
[Continued  from  vol.  xx.  p.  344.] 
Dec.  21,  1841 . — The  following  communications  were  read  : — 
"  On  the  Agency  of  Caloric  in  permanently  modifying  the  state 


314-  Chemical  Society. 

of  Aggregation  of  the  Molecules  of  Bodies,"  by  Warren  De  la  Rue, 
Esq. 

The  subject  of  this  short  notice  is  the  practical  application  of  the 
action  which  takes  place  in  masses,  composed  of  palpable  particles, 
when  raised  to  a  temperature  insufficient  even  for  their  partial  fu- 
sion. 

In  illustration  of  the  particular  action  alluded  to,  may  be  quoted 
the  following  familiar  facts  : — Precipitated  gold,  when  heated  to  a  low 
red  heat,  contracts  in  volume,  becomes  more  coherent  and  yellow  in 
colour ;  clay  contracts  in  volume  when  heated,  and  generally  in  pro- 
portion to  the  intensity  of  the  heat ;  the  carbonaceous  deposit  in  the 
inside  of  gas  retorts,  by  the  continued  action  of  heat,  acquires  suffi- 
cient hardness  to  scratch  glass ;  ordinary  coke  and  charcoal  become 
harder  the  longer  the  action  of  heat  is  continued  on  them  ;  these  and 
many  other  analogous  facts  are  examples  of  a  new  molecular  arrange- 
ment being  produced  in  various  substances,  by  subjecting  them  to  an 
increase  of  temperature,  not  however  sufficient  for  their  fusion. 

To  cause  the  foregoing  changes  a  red  heat  is  employed ;  we  shall 
however  presently  see  that  a  temperature  but  little  above  that  of 
boiling  water  is  quite  sufficient  to  materially  alter  the  cohesion  of 
some  substances. 

It  may  be  as  well  here  to  premise,  that  the  particles  should  be 
brought  as  closely  as  possible  together ;  to  effect  this,  if  the  sub- 
stance be  in  powder,  it  must  be  made  into  a  paste  with  water  to 
displace  the  air,  and  the  paste  so  prepared  submitted  to  a  pressure  of 
four  tons  or  upwards  on  the  square  inch ;  air  being  so  exceedingly 
compressible  it  cannot  be  got  rid  of  without  the  use  of  some  liquid. 
The  manner  of  pressing  need  not  here  be  entered  on,  the  operation 
being  purely  mechanical. 

White  lead  precipitated  by  carbonic  acid  gas  from  a  hot  solution 
of  the  sub-nitrate  always  falls  as  an  exceedingly  light  deposit ;  if  it 
be  pressed  as  before  described,  and  the  pressed  cake  dried  at  the  or- 
dinary temperature  of  the  atmosphere,  it  coheres  but  imperfectly,  but 
on  being  subjected  to  a  heat  of  between  200°  and  300°  Fahrenheit, 
it  becomes  exceedingly  hard  and  compact ;  and  if  the  cake  be  ground 
up  with  water  and  redried,  it  will  be  found  far  more  dense  and  opake 
than  the  original  precipitate,  showing  the  change  to  be  permanent. 

The  following  fact  was  communicated  to  me  by  Messrs.  Nasmyth 
and  Co.  of  Patricroft : — Common  chalk  cannot  readily  be  sawn  into 
thin  slips,  as  it  crumbles  under  the  operation ;  if  however  it  be  baked 
at  the  temperature  before  named  it  becomes  far  more  tenacious,  and 
may  be  then  cut  into  any  form  we  choose,  still  being  sufficiently  soft 
for  drawing  or  writing,  to  which  purposes  it  is  far  more  applicable 
than  before  baking. 

Almost  all  precipitates  dry  much  more  crisp  at  high  than  at  low 
temperatures,  the  agency  of  heat  facilitating  the  attraction  of  such 
particles  as  may  happen  to  be  in  contact. 

In  conclusion,  I  may  remark  that  it  appears  by  no  means  impro- 
bable that  the  long- continued  action  of  temperatures,  but  slightly 
elevated  above  the  ordinary  temperature  of  the  atmosphere,  may 


Chemical  Society.  315 

have  been,  and  still  may  be,  the  cause  of  the  formation  of  hard  rocks 
from  materials  originally  but  slightly  coherent. 

"  Notice  of  the  Decomposition  of  Oxalic  Methylic  yEther  (Oxa- 
late of  Oxide  of  Methyl)  by  Alcohol,"  by  Henry  Croft,  Esq. 

While  in  Berlin  I  was  led  to  examine  the  action  of  potassa  on 
oxalate  of  methyl,  by  a  statement  of  Weidmann  and  Schweitzer  in 
their  first  treatise  on  Wood-spirit ;  namely,  that  the  compounds  of 
the  oxide  of  methyl  with  acids  are  decomposed  by  alkalies,  not  into 
their  constituent  acid  and  wood-spirit,  as  Dumas  and  Peligot  have 
stated,  but  into  the  acid  and  a  peculiar  oil  which  they  called  methol. 
From  this  Lbwig  drew  some  conclusions  unfavourable  to  the  accu- 
racy of  Dumas  and  Peligot's  research.  This  statement  of  Weidmann 
and  Schweitzer  I  found  to  be  incorrect,  as  they  themselves  also  al- 
lowed in  their  second  paper.  Oxalate  of  methyl  is  best  prepared  by 
distilling  a  mixture  of  1  part  wood-spirit,  1  part  anhydrous  oxalic 
acid  (HO  +  O203),  and  from  £th  to  ^th  of  sulphuric  acid.  The 
first  portion  which  passes  over  may  be  returned,  and  afterwards  an- 
other part  of  wood- spirit  added,  or  even  two.  The  aether  obtained 
must  not  be  allowed  to  stand  in  solution  for  any  length  of  time,  for 
it  easily  decomposes.  The  above  proportions  I  have  found  to  be  the 
best ;  the  method  with  oxalic  acid  alone  is  troublesome,  on  account 
of  the  great  volatility  of  wood-spirit,  and  the  length  of  time  required 
for  forming  any  considerable  quantity  of  the  aether.  If,  on  the  other 
hand,  so  much  as  an  equal  weight  of  sulphuric  acid  is  taken,  the 
mixture  becomes  brown  or  black,  and  towards  the  end  of  the  ope- 
ration sulphurous  acid,  methol,  and  other  products  are  formed.  By 
passing  hydrochloric  acid  gas  into  a  solution  of  oxalic  acid  in  wood- 
spirit  no  aether  could  be  obtained ;  it  is  possible,  however,  that  the 
result  of  further  experiments  may  be  more  favourable,  only  one  ex- 
periment being  made,  owing  to  the  very  small  quantity  of  wood- 
spirit  in  my  possession. 

It  is  well  known  that  Mitscherlich  formed  the  oxalovinate  of  po- 
tassa by  adding  to  an  alcoholic  solution  of  oxalic  aether  just  so  much 
of  an  alcoholic  solution  of  potassa  as  was  sufficient  to  saturate  half 
the  oxalic  acid  contained  in  the  aether.  As  no  acid  oxalate  of  methyl 
is  known,  I  therefore  attempted  to  form  it  in  the  same  manner,  but 
owing  to  the  excessively  small  quantity  of  spirit  which  I  possessed, 
and  which  is  not  to  be  obtained  in  northern  Germany,  I  was  obliged 
to  dissolve  both  the  oxalic  methylic  aether  and  the  potassa  in  alcohol, 
it  appearing  very  unlikely  that  the  alcohol  could  have  any  disturb- 
ing influence,  as  it  is  only  the  aether  which  ought  to  be  decomposed. 
On  adding  the  solution  of  potassa  until  the  mixture  became  slightly 
alkaline,  a  white  salt  in  pearly  scales  was  obtained ;  this  was  washed 
with  alcohol  and  dried.  The  filtered  solution  gave  more  of  it  on 
evaporation. 

In  analysing  this  substance  it  was  useless  to  attempt  to  determine 
the  carbon  and  hydrogen,  owing  to  the  admitted  insecureness  of  the 
analyses  of  potash  salts,  and  I  had  not  enough  material  to  prepare 
either  the  lead  or  baryta  salt.  The  oxalic  acid  and  the  potassa  were 
therefore  alone  determined  :  it  contained,— 1st,  3081,  and  2nd,  30"76 


316  Chemical  Society. 

per  cent,  of  potassa,  and  46'58  of  oxalic  acid.  This  agrees  very  well 
with  the  formula  for  oxalomethylate  of  potassa,  plus  one  atom  of 
water ;  but  no  water  could  be  driven  out  by  a  heat  of  150°  C,  and  I 
at  length  found  that  the  salt  was  only  oxalovinate  of  potash,  with 
the  composition  of  which  the  analyses  agree  very  well : — 

1.  2. 

Oxalic  acid  .    .    .     46-12  46"58 

Potassa     ....     3004  3076       30*81 . 

The  salts  agreed,  moreover,  completely  in  their  properties.  On  re- 
peating the  experiment  with  wood- spirit  instead  of  alcohol  I  did  not 
obtain  an  insoluble  salt,  but  on  evaporation  one  which  is  probably  the 
true  oxalomethylate  of  potash,  and  which  I  am  now  about  examining. 

Such  a  decomposition  as  the  above  is,  I  believe,  of  very  rare  oc- 
currence ;  I  am  not  aware  of  any  other  instance  of  it  being  known, 
although  the  possibility  of  some  such  kind  of  decomposition  has  not 
escaped  the  acuteness  of  Berzelius.  (Lehrbuch,  viii.  703.)  We  may 
perhaps  suppose  that  oxalomethylate  of  potash  is  first  formed,  but 
that  the  attraction  of  oxalic  acid  for  aether,  and  of  oxalic  aether  for 
oxalate  of  potash  is  so  strong  as  to  cause  the  decomposition  of  hy- 
drate of  aether  into  its  elements,  when  the  alcoholic  aether  will  com- 
bine with  the  oxalic  acid,  and  the  oxide  of  methyl,  whose  place  it 
takes,  combines  with  water  to  form  wood-spirit.  That  some  kind 
of  what  is  called  predisposing  affinity  is  here  in  play,  is  evident  from 
the  fact  that  oxalate  of  methyl  may  be  boiled  with  alcohol  for  hours 
without  any  such  change  taking  place. 

It  may  be  stated,  in  conclusion,  that  the  process  last  described  is 
a  very  good  and  oeconomical  method  of  obtaining  the  oxalovinate  of 
potassa  in  a  very  beautiful  form. 

"  On  the  Radical  of  the  Cacodyl  Series  of  Compounds,"  by  Pro- 
fessor Bunsen  of  Marburg.     (In  Phil.  Mag.  S.  3.  vol.  xx.  p.  382.) 

Jan..  4, 1842. — The  following- communications  were  read  ; — 

"  On  some  of  the  Substances  contained  in  the  lichens  employed 
for  the  preparation  of  Archil  and  Cudbear,"  by  Edward  Schunck, 
Esq.  (This  paper  will  be  found  in  Phil.  Mag.  S.  3.  vol.  xx.  p.  495.) 

"  On  a  re-arrangement  of  the  Molecules  of  a  Body  after  soli- 
dification," by  Robert  Warington,  Esq.  (Inserted  in  Phil.  Mag.  S.  3. 
vol.  xx.  p.  537.) 

Jan.  18. — Colonel  Yorke  exhibited  a  specimen  of  a  silver  ore  from 
Mexico,  containing  bromide  of  silver,  from  his  collection,  in  confir- 
mation of  the  late  discovery,  by  M.  Berthier,  of  the  existence  of 
bromine  in  silver  ores. 

The  following  communications  were  read  : — 

"  On  the  Conversion  of  Benzoic  Acid  into  Hippuric  Acid,  in  the 
Animal  Economy,"  by  Mr.  Alfred  Baring  Garrod,  of  University  Col- 
lege.    (In  Phil.  Mag.  S.  3.  vol.  xx.  p.  501.) 

'  On  the  Constitution  of  the  Sulphates,  as  illustrated  by  late 
Thermometrical  Researches,"  by  Thomas  Graham,  Esq.,  F.R.S.  (In 
Phil.  Mag.  S.  3.  vol.  xx.  p.  539.) 

February  1 . — The  following  communication  was  read  : — 

'*  On  the  Change  of  Colour  in  the  Biniodide  of  Mercury,"  by 


Chemical  Society.  317 

Robert  Warington,  Esq.,  Sec.  Chem.  Soc.    This  paper  will  be  found 
at  p.  192  of  the  present  volume. 

February  15. — The  following  communications  were  read  : — 

"  On  a  new  Oxalate  of  Chromium  and  Potash,"  by  Henry  Croft, 
Esq.     For  this  paper  also  see  pres.  vol.  p.  197. 

"  Some  Observations  on  Brewing,"  by  Septimus  Piesse,  Esq. 

The  author's  attention  was  directed  to  the  subject  by  the  follow- 
ing inquiry  : — "  Is  it  possible  to  obtain  a  greater  quantity  of  extract 
from  malt  by  any  other  process  than  that  usually  followed  ?  Is  any 
thing  left  in  the  grains  which  ought  to  be  in  the  wort  ? " 

Now  from  an  examination  of  several  samples  of  the  malt  taken 
when  supposed  to  be  completely  exhausted,  and  from  the  circum- 
stance of  the  grains  affording  such  a  large  quantity  of  nourishment 
to  cattle,  I  was  led  to  suspect  that  it  was  possible  to  increase  the 
weight  of  extract ;  in  fact,  the  grains  were  found  to  contain  a  nota- 
ble quantity  of  starch. 

The  non-conversion  of  this  starch  into  sugar  does  not  depend,  in 
the  cases  I  have  witnessed,  upon  the  use  of  improper  temperatures, 
but  arises  from  a  deficiency  of  diastase  (the  principle  which  effects 
the  change  of  starch  into  sugar).  In  the  ordinary  process  of  brew- 
ing, a  certain  quantity  of  water  and  malt  are  mixed  together  of  a 
proper  temperature.  After  standing  for  a  time,  this  water,  or  as  it 
is  then  termed,  wort,  is  drained  from  the  malt,  and  a  second  portion 
of  water  is  run  on  to  form  the  second  wort.  There  can  be  no  doubt 
but  the  principal  portion  of  the  starch  is  converted  during  the  first 
mashing,  but  it  never  is  all.  Now  it  must  be  remembered  that  as 
diastase  is  soluble,  it  is  taken  up  by  the  first  wort,  and  when  that  is 
run  off,  the  diastase  passes  away  also.  The  improvement  consists 
simply  in  adding  diastase  to  the  second  wort,  to  convert  the  remain- 
ing starch  into  sugar.  This  is  done  by  the  addition  of  a  portion  of 
malt  (which  contains  diastase)  previous  to  mashing  a  second  time. 
In  a  brewing  of  30  quarters,  I  should  take  29  quarters  for  the  first 
mash,  and  add  the  remaining  quarter  to  the  second.  There  is  such 
an  increase  as  to  warrant  me  in  advising  its  adoption  by  all  brewers 
and  distillers. 

Another  improvement  in  brewing  is  recommended  by  the  author, 
to  prevent  the  absorption  of  oxygen  by  the  wort,  and  thus  in  a  great 
measure  prevent  acidity. 

The  wort,  as  it  flows  from  the  tun,  passes  into  the  underback, 
according  to  the  usual  practice,  where  it  is  exposed  to  the  air ;  and 
that  for  some  time,  because  the  wort  must  run  slowly  in  order  to 
come  bright.  The  improvement  consists  in  having  a  float  in  the 
back,  that  is,  a  surface  of  wood  the  size  of  the  bottom  of  the  back, 
upon  which  it  rests  when  empty.  As  the  wort  runs  into  the  back 
the  float  rises  with  it,  and  falls  again  when  it  is  pumped  up  to  the 
copper,  thus  effectually  keeping  it  out  of  the  contact  of  air  previous 
to  boiling,  when  the  danger  ceases.  When  this  precaution  has  not 
been  taken,  I  have  invariably  found  the  wort  to  indicate  more  or  less 
acid,  which  may  be  looked  upon  as  likely  to  lead  to  sour  beer. 
March  1 . — The  following  communications  were  read  : — 


318  Chemical  Society: — Mr.  Hutchinson  on  the 

"On  the  Preparation  of  Cyanide  of  Potassium,  and  its  applica- 
tions," hy  Professor  Liebigof  Giessen.  (Inserted  in  vol.  xx.  p.  2G5.) 

"  On  the  Specific  Heat  and  Conducting  Power  of  Building  Ma- 
terials," by  John  Hutchinson,  Esq. 

The  following  is  the  substance  of  Mr.  Hutchinson's  paper  : — The 
author,  after  mentioning  the  state  of  our  knowledge  respecting  the 
conducting  powers  for  heat  of  different  substances,  proceeds  to  point 
out  an  important  source  of  error  in  all  such  investigations  hitherto 
made  arising  from  the  neglect  of  correction  for  differences  of  specific 
heat  among  the  bodies  examined ;  the  effects  observed  being  evi- 
dently mixed  effects,  arising  from  both  causes.  This  being  the  case, 
before  any  correct  investigation  of  the  relative  conducting  powers 
of  building  materials  referred  to  could  be  advantageously  undertaken, 
it  became  indispensable  to  acquire  a  previous  knowledge  of  their 
relative  capacities  for  heat,  in  order  that  correction  for  differences 
of  this  kind  might  be  made.  This  inquiry,  therefore,  naturally  pre- 
ceding that  of  the  proper  subject  of  the  paper,  first  attracted  the 
author's  attention. 

The  building  materials  selected  for  experiment  were  the  following  : 
— Oak,  beech  and  fir-woods  ;  common,  facing  and  fire-brick ;  As- 
phalte  composition,  hair  and  lime  mortar,  lath  and  plaster,  Roman 
cement,  plaster  and  sand,  plaster  of  Paris,  Keene's  cement ;  slate, 
Yorkshire  flag-stone,  Lunelle  marble,  Napoleon  marble,  Portland 
and  Bath-stone  ;  and  lastly,  three  specimens  of  the  stones  now  used 
in  building  the  Houses  of  Parliament. 

The  plan  of  experimenting  chosen  was  that  known  as  the  "  method 
of  mixture,"  this  appearing  by  all  evidence  on  the  subject  to  be  the 
most  unobjectionable.  The  process  followed  differed  but  little  from 
that  described  by  Regnault  in  his  recent  researches.  A  suitable  quan- 
tity of  material  in  fragments  being  accurately  weighed  out  and  placed 
in  a  little  wire  basket  with  the  bulb  of  a  delicate  thermometer  in  the 
midst,  the  whole  was  exposed  in  au  inclosure  heated  by  steam  until 
the  thermometer  ceased  to  rise,  when  the  basket  was  withdrawn  and 
plunged  with  suitable  precautions  into  a  vessel  of  water  at  a  tempe- 
rature a  little  below  that  of  the  atmosphere.  After  the  lapse  of  a 
very  short  interval  the  temperature  of  the  water  was  carefully  ob- 
served, and  its  rise  gave  the  means  of  calculating  the  specific  heat 
of  the  substance. 

The  author  remarks  on  the  necessity  of  equalizing  as  much  as  pos- 
sible the  times  of  heating  of  the  different  substances,  having  observed 
a  great  difference  in  the  results  given  by  the  same  body  when  slowly 
and  when  quickly  raised  to  the  high  temperature  required  for  the  ex- 
periment, and  attributes  this  difference  to  an  alteration  in  the  state 
of  the  currents  or  waves  of  heat  travelling  inwards  towards  the  centre 
of  the  solid. 

A  number  of  minute  precautions,  indispensable  to  a  correct  result, 
were  also  pointed  out  and  exemplified.  The  results  of  the  investiga- 
tion were  given  in  a  tabular  form,  and  the  principle  of  the  calculation 
described. 

With  the  knowledge  thus  obtained  the  author  proceeded  with  his 


Specific  Heat  and  Conducting  Power  of  Building  Materials.  319 

inquiries  respecting  the  conducting  powers  of  the  substances  under 
examination. 

The  plan  usually  adopted  in  this  kind  of  research,  namely,  ob- 
serving by  the  aid  of  thermometers  the  time  occupied  by  the  passage 
of  a  certain  amount  of  heat  lengthways  through  the  substance  of  a 
prism,  one  end  of  which  was  exposed  to  a  high  and  constant  tem- 
perature, having  failed  on  trial  with  these  bodies,  in  consequence  of 
their  feeble  conducting  powers,  the  following  method  was  had  re- 
course to  with  perfect  success  : — The  various  substances  examined 
were  cut  with  the  greatest  care  into  cubes  of  2*8  inches  in  the  side, 
and  a  hole  drilled  in  the  centre  of  one  of  the  faces  half  way  through, 
large  enough  to  receive  the  bulb  of  an  exceedingly  sensitive  thermo- 
meter, together  with  a  little  mercury  to  improve  the  contact  with  the 
substance  of  the  cube.  The  temperature  of  the  mass  being  exactly 
observed,  it  was  next  plunged,  all  but  its  upper  surface,  into  a  large 
bath  of  mercury  heated  by  steam,  whose  temperature  remained  con- 
stant at  211°,  and  the  time  of  rise  of  the  thermometer  for  every  suc- 
cessive 10°  accurately  noted  until  the  maximum  was  reached,  thus 
affording  a  comparison  of  the  relative  conducting  powers,  or  perhaps 
more  properly,  resistance  to  the  passage  of  heat  towards  the  centre 
of  the  mass. 

In  the  course  of  these  experiments  a  very  extraordinary  circum- 
stance was  observed  :  although  the  greatest  care  was  taken  to  equal- 
ize the  temperature  of  the  cubes  by  suffering  them  to  remain  at  least 
twenty-four  hours  before  experimenting  in  an  uniform  temperature, 
yet  they  never  exactly  acquired  that  of  the  room,  or  even  agreed 
among  themselves  in  this  respect ;  an  observation  which  led  the  au- 
thor to  the  suspicion  that  the  generally  received  doctrine  of  an  equal 
distribution  of  sensible  heat  among  bodies  in  contact  and  not  influ- 
enced by  external  sources  of  disturbance,  might  not  prove  strictly 
true,  but  that,  on  the  contrary,  each  of  a  number  of  different  sub- 
stances, exposed  under  similar  circumstances  to  the  influence  of  a 
medium  of  uniform  temperature,  acquires  a  proper  temperature  of  its 
own.  The  same  thing  was  observed  with  higher  degrees  of  heat ;  a 
mass  of  slate,  for  example,  plunged  beneath  the  surface  of  uniformly 
heated  mercury  and  maintained  there  long  after  the  thermometer  in 
the  slate  had  reached  its  maximum,  always  exhibited  a  temperature 
decidedly  below  that  of  the  surrounding  metal*. 

A  third  series  of  experiments  were  made  with  a  view  of  ascer- 
taining the  relative  rates  of  cooling  in  air  of  the  various  materials 
examined,  from  a  higher  temperature  to  that  of  the  atmosphere. 
The  arrangement  consisted  of  the  cubes  before  described,  covered 
externally  with  thin  paper  for  the  sake  of  uniformity  of  surface,  the 
same  delicate  thermometer  being  inserted  in  the  hole  in  the  centre, 
together  with  a  little  mercury  for  the  sake  of  contact.  The  cubes 
were  each  in  turn  heated  in  the  steam-chest  used  for  the  specific 
heat  experiments,  until  the  included  thermometer  rose  to  200° ;  they 
were  then  removed,  suspended  in  the  air,  and  the  time  of  fall  of  tem- 
perature for  every  10  degrees  carefully  no'.ed. 

[*  On  this  subject  a  paper  by  Mr.  Parnell  was  subsequently  read,  an 
abstract  of  which  will  appear  in  a  future  Number. — Edit.] 


320  Intelligence  and  Miscellaneous  Articles. 

The  precautions  required  to  be  taken  to  avoid  errors  of  different 
kinds  were  fully  described,  and  drawings  of  the  apparatus  used  ex- 
hibited, together  with  a  most  elaborate  and  complete  set  of  tables 
embodying  the  whole  of  the  results. 


LIV.   Intelligence  and  Miscellaneous  Articles. 

BICHLORIDE  OF  HYDROGEN. 
r|1HIS  compound,  which  contains  one  proportion  of  chlorine  more 
-■•  than  exists  in  hydrochloric  acid,  may  be  obtained,  according  to  M. 
Millon,  by  slowly  and  gradually  projecting  binoxide  of  lead  into  con- 
centrated hydrochloric  acid,  surrounded  by  a  cooling  mixture  of  ice 
and  salt.  In  the  reaction  which  occurs  under  these  circumstances, 
the  liquor  produced  assumes  a  deep  yellow  colour,  without  any  sen- 
sible disengagement  of  chlorine,  and  an  abundance  of  protochloride 
[of  lead]  is  formed. 

The  bichloride  of  hydrogen,  which  gives  the  liquor  its  colour  and 
properties,  has  not  yet  been  separated  from  the  medium  in  which  it 
is  dissolved.  This  compound  possesses  but  little  stability,  for,  at 
common  temperatures,  it  continues  to  evolve  chlorine  during  several 
days.  Mercury  decomposes  it  by  absorbing  part  of  the  chlorine, 
and  thus  causing  the  reproduction  of  hydrochloric  acid.  Its  compo- 
sition would  appear  to  be  1  equivalent  of  hydrogen  -f-  2  equiva- 
lents of  chlorine  =  H  Ch'2. 

This  bichloride  would  be  formed  by  the  reaction  of  3  equivalents 
of  hydrochloric  acid,  or  1  equivalent  of  binoxide  of  lead,  as  shown 
by  the  annexed  equation  : 

3  H  Ch,  +  Pb  O2  =  Pb  Ch  +  2  H  O,  +  H  Ch2. 

Journal  de  Chim.  Me'dicale,  Juillet  1842. 


ON  THE  ACTION  OF  CHLORIDES  UPON  PROTOCHLORIDE  OF  MER- 
CURY.     BY  M.  MIALHE. 

M.  Mialhe  remarks  that  Capelle,  in  1763,  first  observed  the  dan- 
ger arising  from  a  mixture  of  calomel  and  sal-ammoniac  ;  Proust  after- 
wards proved  the  conversion  of  calomel  into  corrosive  sublimate  by 
the  action  of  the  alkaline  chlorides.  After  mentioning  other  au- 
thors, M.  Mialhe  refers  to  a  note  of.  his  own  contained  in  the  Jour- 
nal de  Pharmacie  for  February  1840,  in  which  he  details  experiments 
proving, — 1st,  that  calomel  acted  upon  by  the  alkaline  chlorides  al- 
ways yields  more  or  less  corrosive  sublimate  ;  2ndly,  that  it  is  to 
this  partial  conversion  calomel  owes  its  medicinal  powers;  and  he 
afterwards  mentions  different  authors  who  have  confirmed  his  opi- 
nions. 

M.  Mialhe  then  relates  various  experiments  which  he  has  since 
performed  to  determine  the  proportion  of  corrosive  sublimate  result- 
ing, under  certain  conditions,  from  this  action. 

Experiment  I. — 1000*  parts  of  distilled  water,  GO  of  common  salt, 
60  of  sal-ammoniac,  and  60  of  calomel  (<l  la  vapeur)  which  had  been 

*  We  have  reduced  the  French  weights  of  the  original  to  parts. 


Intelligence  mid  Miscellaneous  Articles.  321 

perfectly  washed,  were  mixed  and  allowed  to  react  for  twenty-four 
hours,  the  temperature  varying  from  68°  to  77°  Fahr.;  there  was 
produced  0*6  of  a  part  of  corrosive  sublimate. 

Similar  experiments  were  made  with  calomel  prepared  by  preci- 
pitation, with  precisely  similar  results. 

Experiment  II. — 1000  parts  of  the  assay  liquor*  had  60  parts  of 
calomel  (tl  la  vapeur)  digested  in  it  for  24  hours,  at  a  temperature 
varying  from  104°  to  128°  Fahr.;  1*5  part  of  corrosive  sublimate 
was  produced. 

The  preceding  experiments  repeated  with  precipitated  calomel 
(precipite  blanc),  yielded  a  mean  of  1*7  part  of  corrosive  sublimate. 
This  chemical  result  confirms  the  opinion  of  therapeutists,  who  have 
always  considered  the  calomel  obtained  by  precipitation  as  sensibly 
more  active  than  that  prepared  in  the  dry  way. 

The  following  question  was  then  examined :  Is  the  quantity  of 
sublimate  produced  proportional  to  that  of  the  calomel  employed,  or 
to  that  of  the  alkaline  chloride  ? 

1st  Experiment. — Assay  liquor  1000  parts,  calomel  10  parts  ;  after 
reacting  for  twenty-four  hours,  between  104°  and  112°  Fahr.,  1*4 
part  of  sublimate  was  produced. 

2nd  Experiment. — Assay  liquor  1000  parts,  calomel  20  parts ; 
sublimate  produced  1*5  part. 

3rd  Experiment. — Assay  liquor  1000  parts,  calomel  40  parts ; 
sublimate  formed  1*5  part. 

4th  Experiment. — Assay  liquor  1000  parts,  calomel  60  parts , 
sublimate  produced  1*5  part. 

The  preceding  experiments  repeated  with  calomel  obtained  by 
precipitation,  gave 

1st  Experiment. — Assay  liquor  1000  parts,  calomel  10  parts ; 
sublimate  produced  1  *4  part. 

2nd  Experiment. — Assay  liquor..  1000  parts,  calomel  20  parts  ; 
sublimate  produced  1*4  part. 

3rd  Experiment. — Assay  liquor  1000  parts,  calomel  40  parts  ; 
sublimate  produced  1*5  part. 

4th  Experiment. — Assay  liquor  1000  parts,  calomel  60  parts ; 
sublimate  produced  1*7  part. 

All  these  experiments  show  that  the  quantity  of  sublimate  pro- 
duced is  not  at  all  proportional  to  that  of  the  calomel  employed. 

The  experiments  about  to  be  related,  prove  beyond  all  doubt, 
that  the  quantity  of  sublimate  formed  is  always  in  proportion  to 
that  of  the  alkaline  chloride. 

1st  Experiment. — After  twenty-four  hours'  contact,  between  the 
temperature  of  104°  and  122°  Fahr.,  distilled  water  1000  parts, 
calomel  20  parts,  common  salt  and  sal-ammoniac  each  60  parts ; 
sublimate  produced  1*6  part. 

2nd  Experiment. — Calomel  240  parts,  commomsalt  and  sal-am- 
moniac each  10  parts ;  sublimate  produced  0*5  part. 

*  To  avoid  repetition,  the  author  calls  the  solution  of  alkaline,  just  de- 
scribed, the  assay  liquor. 

Phil.  Mag.  S.  3.  Vol.  21.  No.  138.  Oct.  1842.  Y 


322  Intelligence  and  Miscellaneous  Articles. 

These  two  experiments,  repeated  with  precipitated  calomel,  gave 
the  following  results  : — 

1st  Experiment. — Sublimate  1*8  part. 

2nd  Experiment. — Sublimate  0*6  part. 

Experiments  were  then  made  to  decide  the  question,  whether  the 
degree  of  dilution  of  the  alkaline  chlorides  put  into  contact  with  the 
calomel,  had  any  remarkable  influence  on  the  quantity  of  sublimate 
produced :  this  was  found  to  be  the  case,  as  indeed  theory  would 
indicate. 

It  was  also  proved,  by  direct  experiment,  that  the  presence  of 
neutral  organic  bodies  does  not  hinder  the  conversion  of  calomel 
into  sublimate ;  on  the  contrary,  dextrine  favours  the  change;  sugar 
and  albumen  probably  do  not  modify  it ;  and  lastly,  lard  and  gum- 
arabic  very  evidently  retard  it. 

M.  Mialhe  remarks,  that  in  his  first  experiments  on  the  conver- 
sion of  calomel  into  sublimate,  he  supposed  it  to  take  place  by  the 
conversion  of  1  equivalent  of  calomel  into  1  equivalent  of  mercury 
and  1  of  sublimate ;  he  now  finds  that  the  presence  or  absence  of 
atmospheric  air  modifies  the  results. 

1st  Experiment. — Without  the  presence  of  air.  Water  2000 
parts,  common  salt  and  sal-ammoniac  of  each  120  parts,  precipi- 
tated calomel  60  parts,  digested  for  twenty-four  hours  in  a  stopped 
bottle  ;  sublimate  produced  0"3  part. 

2nd  Experiment. — The  same  substances  allowed  to  react  with  the 
presence  of  the  air,  yield  IT  part  of  sublimate. 

It  appears,  then,  that  calomel  and  the  alkaline  chlorides,  when 
air  is  present,  produce  three  times  as  much  sublimate  as  when  they 
react  without  it.  The  explanation  of  this  appears  to  be,  the  fact,  as 
stated  by  M.  Guibourt,  that  calomel  absorbs  a  certain  quantity  of 
oxygen  at  common  temperatures ;  at  a  higher  temperature  the  ab- 
sorption is  greater ;  and  in  the  case  now  mentioned,  the  absorption 
is  accelerated  by  the  presence  of  the  alkaline  chlorides.  It  is  not 
therefore  surprising  that  the  proportion  of  sublimate  should  be 
greater  when  the  air  is  present,  since  for  every  equivalent  of  oxygen 
absorbed,  an  equivalent  of  sublimate  is  produced  ;  and  moreover 
each  equivalent  of  binoxide  of  mercury  formed,  gives  by  double  de- 
composition with  the  alkaline  chloride,  1  equivalent  of  sublimate 
and  1  of  alkaline  oxide. 

To  check  these  researches,  the  following  experiments  were  made  : 

1st  Experiment. — Water  1000  parts,  calomel  and  hydrochloric 
acid  each  60  parts,  digested  twenty-four  hours  at  temperatures 
between  104°  and  122°  Fahr. ;  sublimate  produced,  without  the 
contact  of  air,  0*4  part. 

2nd  Experiment. — The  same  substances,  reacting  with  air  present, 
gave  T4  part  of  sublimate. 

It  may  be  concluded  from  the  foregoing,  that  about  two-thirds  of 
the  sublimate  produced  are  formed  by  the  influence  of  oxygen,  and 
that  one- third  only  is  derived  from  the  mere  and  simple  conversion 
of  calomel  into  metallic  mercury  and  calomel. 

M.  Mialhe  finds  also,  that  calomel  may  partly  be  converted  into 


Intelligence  and  Miscellaneous  Articles.  323 

sublimate,  &c.  by  the  influence  of  boiling  distilled  water  deprived 
of  air.  1000  parts  of  boiling  distilled  water  and  60  parts  of  calomel 
were  kept  at  212°  for  an  hour;  after  cooling,  the  water  was  found 
to  contain  0*  1  part  of  sublimate. 

This  experiment  repeated  with  precipitated  calomel  gave  0*1  part 
of  sublimate. 

When  calomel  then  is  boiled  in  distilled  water,  sublimate  is  un- 
questionably produced  without  the  contact  of  air,  but  the  quantity 
produced  is  infinitely  smaller  than  when  oxygen  is  present ;  but  in 
this  case  it  is  oxichloride  of  mercury  which  is  formed,  and  not  mere 
bichloride  of  mercury. — Annates  de  Chimie  et  de  Physique,  Juin  1842. 


ON  CINCHOVATINA — A  NEW  VEGETABLE   ALKALI. 

M.  Manzini  obtained  this  alkali  from  the  Cinchona  ovata,  which 
has  always  been  admitted  not  to  possess  any  febrifuge  power.  The 
process  employed  in  preparing  this  substance  was  exactly  similar  to 
that  used  for  obtaining  quina. 

Its  properties  are,  it  crystallizes  in  prisms,  which  are  longer  than 
those  of  cinchonia  ;  they  are  white,  inodorouss  bitter,  but  this  is  long 
in  being  developed,  on  account  of  the  slight  solubility  of  this  sub- 
stance. Alcohol  dissolves  it  very  well,  especially  when  hot,  but 
aether  is  not  so  perfect  a  solvent,  and  in  water  it  is  almost  insoluble. 
Dilute  acids  dissolve  it  readily  and  form  salts,  which  usually  crystal- 
lize readily,  are  very  soluble  even  in  weak  alcohol,  but  more  so  when 
hot  than  cold  ;  these  salts  are  decomposed  by  the  alkalies  and  their 
carbonates,  which  precipitate  cinchovatina ;  they  are  also  decomposed 
by  tannin,  iodide  of  potassium,  bichloride  of  mercury,  chloride  of 
platina,  chloride  of  gold  and  other  metallic  chlorides.  Ammonia  also 
precipitates  the  salts  of  cinchovatina,  setting  the  base  at  liberty,  but 
only  a  part  of  it  is  separated  in  an  insoluble  state,  especially  if  the 
excess  of  ammonia  is  considerable ;  a  portion  of  the  base  remains 
dissolved  by  the  ammonia,  and  is  deposited  in  slender  crystals  by  the 
evaporation  of  the  alkali ;  even  that  portion  of  the  cinchovatina 
which  is  precipitated,  and  which  is  perfectly  amorphous,  eventually 
becomes  a  crystalline  mass  of  a  splendid  pearly  whiteness  ;  it  re- 
quires some  days  for  the  production  of  this  change.  The  alcoholic 
solution  of  cinchovatina  is  very  bitter ;  it  restores  the  blue  colour  of 
reddened  litmus,  and  renders  syrup  of  violets  green.  When  subject- 
ed to  a  heat  gradually  increasing  to  366°  Fahr.,  cinchovatina  suffers 
no  loss  of  weight,  nor  any  change  of  appearance  ;  when  heated  in  a 
tube  to  370°  Fahr.  it  melts  into  a  brownish  liquid  without  volatili- 
zing ;  on  cooling  it  solidifies  into  a  mass  of  a  resinous  appearance,  of 
the  colour  of  colophony,  with  its  surface  covered  with  cracks ;  in 
this  state  its  weight  is  the  same  as  before  fusion,  and  if  it  be  melted 
again,  its  fusing  point  is  found  not  to  have  changed.  Cinchovatina, 
therefore,  cannot  be  ranged  with  those  bodies,  which,  as  observed 
by  Wohler  in  his  memoir  on  lithofellic  acid,  possess  the  remarkable 
property,  of  having  two  different  fusing  points,  according  as  they 
are  amorphous  or  crystallized. 

Cinchovatina  which  has  been  fused  and  cooled  is  as  soluble  as 

Y  2 


324  Intelligence  and  Miscellaneous  Articles. 

before  in  boiling  alcohol,  and  is  deposited  in  crystals  on  cooling. 
At  about  374°  Fahr.  it  decomposes,  and  then  yields  extremely  fetid 
empyreumatic  products,  and  leaves  a  very  bulky  charcoal.  These 
experiments  show  that  crystallized  cinchovatina  is  perfectly  anhy- 
drous. 

By  analysis  it  yielded  very  nearly, 

(Foreign  equivalents.) 

Carbon 69;80      or      O6  =  3450-00 

Hydrogen 6"83      . .       H54  =    337'50 

Oxygen 16.21       ..       O8   *=     800-00 

Azote 7-16  Az4  =    353-Q8 

100-        Equivalent  =  3941-50 
Journ.  de  Pharm.  et  de  Chim.,  Aout  1842. 


PREPARATION  OF  PURE  POTASH  AND  SODA. 
M.  Schubert  observes  that  the  mode  of  preparing  caustic  barytes 
from  sulphuret  of  barium,  by  means  of  oxide  of  copper,  admits  of 
its  being  used  for  the  ready  obtaining  of  potash  and  soda  chemically 
pure.  Crystals  of  neutral  sulphate  of  potash  or  sulphate  of  soda  are 
to  be  dissolved  in  a  concentrated  solution  of  caustic  barytes,  until 
chloride  of  barium  shows  an  excess  of  these  salts  in  a  small  quantity 
of  the  filtered  liquor,  then  barytes  water  and  a  solution  of  the  sul- 
phates are  to  be  alternately  used  till  neither  produces  any  precipita- 
tion, and  proving  that  there  is  neither  barytes  nor  sulphate  in  excess. 
It  is,  however,  better  to  have  an  excess  of  barytes  than  of  sulphuric 
acid,  because  the  former  precipitates  during  evaporation  in  the  state 
of  carbonate  ;  but  then  the  evaporated  alkali  must  be  redissolved,  fil- 
tered, and  again  evaporated,  and  these  operations  necessarily  intro- 
duce a  considerable  quantity  of  carbonic  acid  into  the  product. — 
Journal  de  Pharm.  et  de  Chimie,  Aout  1842. 


DETECTION  OF  IODINE  IN  BROMIDES. 

The  presence  of  the  alkaline  iodides  in  the  bromides  which  are 
prepared  with  the  bromine  obtained  from  the  mother  waters  of  soda, 
is  less  rare  than  is  supposed.  This  fact  depends,  as  chemists  well 
know,  on  the  difficulty  found  in  separating  from  bromine,  which  is 
liquid  at  common  temperatures,  the  small  proportions  of  iodine, 
which  exist  in  it  in  the  state  of  bromide.  Various  specimens  of  the 
bromide  of  potassium  of  commerce,  which  have  been  offered  to  M. 
Lassaigne,  constantly  contained  a  very  small  quantity  of  iodide,  and 
it  is  by  the  very  sensible  reaction  of  starch  that  he  has  been  able  to 
detect  it. 

On  adding  to  the  solution  of  bromide  of  potassium  to  be  examined, 
a  few  drops  of  a  weak  solution  of  chlorine,  the  liquid  soon  becomes 
of  a  yellow  colour ;  if  there  then  be  immersed  in  it  white  paper 
starched,  or  covered  with  a  mixture  of  starch  and  water,  and  after- 
wards dried,  it  becomes  of  a  violet  or  of  a  light  indigo  blue  colour. 
This  colour  depends  on  the  iodine  set  free  by  the  first  portions  of 
chlorine  added  to  the  impure  bromide. 


Intelligence  and  Miscellaneous  Articles.  325 

When  sufficient  chlorine  has  been  added  to  decompose  the  whole 
of  the  alkaline  bromide,  the  paper  immersed  is  not  immediately- 
coloured,  for  then  the  iodine  exists  in  the  liquor  in  the  state  of  bro- 
mide, and  no  longer  acts  upon  the  starch ;  but  this  remarkable  cir- 
cumstance occurs,  that  the  paper  being  withdrawn  from  the  liquor 
and  exposed  to  the  air,  the  moistened  part  assumes  a  reddish  tint  in 
about  two  minutes,  then  becomes  violet,  and  afterwards  blue;  the 
same  reaction  occurs,  but  in  a  longer  time,  when  the  starched  paper 
is  left  to  macerate  in  the  liquor. 

This  effect,  unquestionably  owing  to  the  decomposition  of  the 
bromide  of  iodine  by  the  organic  matter  of  the  paper,  or  perhaps 
even  of  the  starch  itself,  admits  of  detecting  minute  quantities  of 
iodine  in  the  alkaline  bromides. — Journal  de  Chim.  Medicate,  Sep- 
tembre  1842. 


PREPARATION  OF  FERROCYANIC  ACID.      BY  M.  POSSELT. 

This  acid,  now  sometimes  also  termed  hydroferrocyanic  acid,  was 
discovered  by  Porret,  and  called  by  him  ferrochyazic  acid.  According 
to  M.Posselt  the  following  is  an  improved  process  for  obtaining  it : — 
agitate  with  aether  a  concentrated  aqueous  solution  of  ferrocyanic 
acid  as  obtained  by  the  decomposition  of  ferrocyanide  of  lead  by 
means  of  sulphuric  or  hydrosulphuric  acid,  the  acid  separates  imme- 
diately and  may  be  obtained  by  filtration ;  this  remarkable  separa- 
tion of  the  acid  from  the  water  which  holds  it  in  solution,  requires 
but  little  aether.  If  the  solution  is  moderately  concentrated,  the 
whole  forms  a  thick  mass  by  agitation,  and  after  some  time  the  fer- 
rocyanic acid  suspended  in  the  aether,  separates  from  the  water  sa- 
turated with  aether,  and  swims  on  the  surface.  The  water  is  to  be 
removed  by  a  pipette ;  the  thick  mass  is  to  be  put  on  a  filter  and 
washed  repeatedly  with  a  mixture  of  alcohol  and  aether,  containing 
a  considerable  portion  of  the  latter ;  it  is  then  to  be  passed  between 
folds  of  absorbent  paper  to  remove  the  moisture,  and  afterwards  to  be 
perfectly  dried  over  sulphuric  acid  in  the  air-pump. 

In  order  to  avoid  preparing  ferrocyanide  of  lead  and  the  aqueous 
solution  of  ferrocyanic  acid,  a  concentrated  solution  of  ferrocy- 
anide of  potassium  may  be  prepared  in  boiled  water,  and  it  is  to 
be  allowed  to  cool,  entirely  excluded  from  the  air  ;  it  is  then  to  'be 
mixed  with  an  excess  of  hydrochloric  acid,  also  deprived  of  air,  and 
this  mixture  is  to  be  shaken  with  aether  in  the  manner  described. 
The  acid  separates  in  the  same  manner,  and  is  to  be  dissolved  in  al- 
cohol, to  which  a  little  sulphuric  acid  is  to  be  added  to  combine 
with  the  potash  which  it  may  still  contain  ;  the  liquor  is  to  be  filter- 
ed if  it  is  not  clear,  and  this  alcoholic  solution  is  to  be  agitated 
with  aether ;  this  again  separates  the  acid,  which  is  to  be  dried  as 
before  described. 

This  substance  possesses  all  the  properties  of  an  acid,  and  presents 
a  complete  analogy  with  other  hydracids.  It  has  a  very  sour  taste, 
an  acid  reaction,  decomposing  the  carbonates  with  effervescence  ;  it 
also  decomposes  with  the  greatest  facility  the  acetates,  tartrates  and 


326  Intelligence  and  Miscellaneous  Articles. 

even  the  oxalates.  It  does  not  when  cold  dissolve  binoxide  of  mer- 
cury ;  but  if  it  be  heated  the  acid  is  decomposed  into  hydrocyanic 
acid,  which  forms  a  cyanide  with  the  mercury  of  the  binoxide,  and 
into  cyanide  of  iron,  which  is  additionally  oxidized  at  the  expense  of 
a  part  of  the  binoxide  of  mercury,  and  metallic  mercury  separates. 

The  ferrocyanic  acid  prepared  by  the  process  described  is  in  the 
state  of  a  white  powder,  frequently  with  a  slight  blue  or  31  ellow  tint. 
When  it  is  perfectly  dry  it  may  be  long  exposed  to  the  air  without 
alteration,  when  moist  the  decomposition  takes  place  more  rapidly ; 
the  acid  becomes  gradually  blue,  and  is  slowly  and  totally  converted 
into  Prussian  blue. 

It  may  be  long  exposed  in  a  covered  platina  crucible  to  a  tempe- 
rature of  212°,  and  excluded  from  the  air,  without  losing  weight  or 
suffering  any  sensible  change ;  eventually,  however,  it  is  decomposed 
under  these  circumstances. 

When  it  is  more  strongly  heated,  hydrocyanic  acid  is  disengaged 
and  cyanide  of  iron  remains,  which  is  oxidized.  If  it  be  heated  in  a 
current  of  carbonic  acid  gas,  and  the  temperature  be  not  raised  above 
212°,  hydrocyanic  acid  is  evolved  and  white  cyanide  of  iron  is  left, 
and  this  decomposes  also  at  a  temperature  somewhat  above  212°.  It 
is,  as  is  well  known,  very  soluble  in  water,  and  the  solution  submit- 
ted to  ebullition  in  contact  with  air  becomes  blue;  but  without  the 
presence  of  air  it  deposits,  on  the  contrary,  white  cyanide  of  iron. 

Ferrocyanic  acid  is  even  more  soluble  in  alcohol  than  in  water.  It 
forms  a  syrupy,  transparent  solution,  which  decomposes  either  by 
long  exposure  to  the  air  or  ebullition.  This  solution  under  the  air- 
pump,  yields  mammillated  hard  crystals  of  a  yellow  colour. 

The  acid  obtained  as  described  is  anhydrous,  not  losing,  as  already 
mentioned,  any  weight  at  a  temperature  of  212°.  Two  analyses  gave 
the  following  results  as  the  composition  of  this  acid  : — 

1.  11.  Calculated. 

Cyanogen     72*71  73*33  73*09 

Hydrogen     1*99  2*27  1-84 

Iron 25*22  25*08  2506 

99*92  10068  99*99 

Journ.  de  Pharm.  et  de  Chimie,  Aout  1842. 


PREPARATION    OF    FERR1DCYANIDE    OF    POTASSIUM. 

M.  Posselt  remarks  that  it  is  well  known  with  what  facility  an 
excess  of  chlorine,  when  passed  through  a  solution  of  ferrocyanide 
of  potassium,  decomposes  the  ferridcyanide  of  potassium  as  it  is 
formed,  and  the  difficulty  which  exists  in  completely  separating  the 
green  substance  which  is  then  produced,  because  it  readily  passes 
through  the  filter.  It  is  only  by  repeated  crystallizations  that  the 
crystals  are  completely  freed  from  it,  and  these  operations  are  always 
attended  with  loss. 

The  following  process  is  stated  by  M.  Posselt  to  give  pure  and 
very  fine  crystals  at  once : — Pass  chlorine  gas  through  a  very  dilute 
solution  of  ferrocyanide  of  potassium,  and  evaporate  it  when  the 


Obituary — Meteorological  Observations.  327 

oxidation  is  complete,  and  add  to  the  boiling  liquor,  when  it  is  near 
its  crystallizing  point,  a  few  drops  of  solution  of  potash  ;  the  green 
substance  is  then  decomposed,  and  flocks  of  peroxide  of  iron  sepa- 
rate. It  is  very  easy  to  observe  the  moment  at  which  the  object  is 
attained,  and  care  must  be  taken  not  to  add  too  much  potash,  be- 
cause an  excess  of  it  would  convert  the  ferridcyanide  of  potassium 
into  ferrocyanide.  The  solution  is  to  be  filtered  hot  to  separate  the 
peroxide  of  iron ;  it  possesses  a  deep  purplish  red  colour,  is  to  be 
cooled  very  slowly,  and  then  fine  crystals  of  the  salt  are  obtained. 

— Ibid.  

OBITUARY. 
We  record  with  much  regret  the  decease  of  our  highly  distin- 
guished correspondent  Mr.  Ivory,  Fellow  of  the  Royal  Society,  and 
Member  of  the  Institute  of  France,  who  died  at  Hampstead  on  the 
2 1st  of  September,  aged  77  : — Also  the  death  of  our  much  respected 
and  venerable  friend  Mr.  Peter  Ewart  (an  occasional  contributor  to 
our  Journal),  occasioned  by  an  accident  in  the  proving  of  a  chain 
cable,  to  which  he  was  attending  in  the  discharge  of  his  duties  at 
"Woolwich.  

METEOROLOGICAL  OBSERVATIONS  FOR  AUGUST  1842. 

Chiswick. — August!.  Overcast:  very  fine.  2.  Sultry.  S.  Sultry:  distant 
thunder.  4.  Sultry  :  high  temperature  maintained  day  and  night.  5.  Cloudy 
and  fine.  6.  Cloudy  :  rain.  7 — 9.  Clear,  hot  and  dry.  10.  Sultry :  excessively 
hot  and  dry  :  heavy  thunder-storm  at  night,  with  rain  in  torrents.  11.  Cloudy: 
clear  and  fine.  12.  Clear  and  fine  throughout.  13.  Overcast:  clear  and  fine. 
14.  Sultry.  15.  Cloudless  and  hot.  16.  Hot  and  dry.  1 7.  Dry  easterly  haze  : 
very  hot.  18.  Excessively  hot  and  sultry :  lightning  in  the  evening.  19,20. 
Cloudy:  fine.  21.  Very  fine.  22.  Hot  and  dry,  with  easterly  wind  :  lightning. 
23.  Cloudless,  hot  and  dry.  24.  Hot  and  dry  :  lightning,  distant  thunder,  with 
wind  and  rain  at  night.  '25.  Overcast :  heavy  thunder-showers  in  the  evening. 
26.  Hazy  :  sultry.  27.  Cloudy  and  fine.  28.  Rain :  cloudy  and  fine.  29. 
Heavy  thunder-showers  early  a.m.  :  violent  thunder-storm  commenced  four  p.m., 
with  very  heavy  rain:  clear  at  night.  30.  Hazy.  31.  Clear  and  fine. — Mean 
temperature  of  the  month  4°  above  the  average. 

Boston.  —  Aug.  1 — 3.  Cloudy.     4.   Fine.     5.  Cloudy.     6.  Rain.     7 — 9.  Fine. 

10.  Fine  :  rain,  with  thunder  and  lightning  p.m.  :  thermometer  85°  three  o'clock. 

11.  Fine.  12.  Cloudy.  13.  Cloudy:  thermometer  79°  two  o'clock  p.m.  14. 
Cloudy:  thermometer  80°  two  o'clock  p.m.  15.  Fine:  thermometer  80°  eleven 
o'clock  a.m.  16.  Foggy.  17.  Cloudy.  18.  Fine:  thermometer  83°  two  o'clock 
p.m.  19.  Cloudy.  20.  Fine.  21,22.  Cloudy.  23.  Fine:  thermometer  82° 
two  o'clock  p.m.  24.  Cloudy:  rain  with  thunder  and  lightning  at  night  25 — 
28.  Cloudy.     29.  Cloudy:  rain  a.m.     30.   Fine:  rain  p.m.     31.   Fine. 

Sandwick  Manse,  Orkney. — An  j.  1,  2.  Clear.  3.  Cloudy  :  damp.  4.  Rain: 
showers.  5.  Showers.  6.  Drops  :  clear.  7.  Bright :  showers.  8.  Clear  :  rain. 
9.  Clear:  cloudy.  10.  Damp:  thunder:  rain.  11.  Showers:  rain.  12.  Show- 
ers :  cloudy.  13.  Bright :  rain.  14.  Drizzle  :  cloudy.  15.  Drizzle :  rain.  16. 
Clear.  17,18.  Clear  :  cloudy.  19.  Fog  :  thunder.  20.  Cloudy.  21.  Showers: 
clear.  22.  Bright :  clear.  23.  Rain.  24.  Clear.  25.  Clear:  cloudy.  26 — 28. 
Clear.     29.   Clear:  cloudy.     30.  Rain:  clear.     31.   Clear. 

Applegarlh  Manse,  Dumfries-shire. — Aug.  1 — 3.  Very  fine.  4.  Showers. 
5.  Showery.  6.  Fine.  7.  Slight  showers.  8.  Rain  p.m.  9.  Showers.  10. 
Heavy  rain  and  thunder.  11.  Fair  and  bracing.  12.  Cloudy  and  drizzly. 
13  Fair  and  fine.  14 — 16.  Very  fine.  17,  18.  Very  fine:  very  hot.  19.  Show- 
ers. 20.  Heavy  showers.  21,22.  Fair  and  bracing.  23.  Fine:  one  shower  : 
thunder.  24.  Wet  a.m.  :  cleared  up.  25—27.  Fair  and  fine.  28.  Fair  and 
fine,  but  hazy.     29—31.  Slight  showers. 


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THE 
LONDON,  EDINBURGH  and  DUBLIN 

PHILOSOPHICAL  MAGAZINE 

AND 

JOURNAL  OF  SCIENCE. 


[THIRD  SERIES.] 


NOVEMBER   1842. 


I 


LV.  Letter  addressed  by  M.  Edmond  Becquerel  to  the  Editors 
of  the  Annales  de  Chimie  et  de  Physique,  in  Reply  to  Mr. 
Daniell's  Letter  to  Mr.  R.  Phillips  on  the  Constant  Voltaic 
Battery,  inserted  in  the  Phil.  Mag.  for  April  1842*. 
N  the  Annates  de  Chimie  et  de  Physique  for  December  184-1 , 
I  published  a  Notice  on  constant  voltaic  batteries,  in 
which  I  stated  the  facts  relating  to  the  subject  just  as  they 
result  from  experiments  performed  by  various  natural  philo- 
sophers who  have  been  occupied  with  this  subject. 

Mr.  Daniel],  thinking  that  I  had  not  done  him  justice,  has 
thought  it  necessary  to  reply  to  several  of  my  assertions  in 
the  Philosophical  Magazine  for  April  1842.  It  was  far  from 
my  intention  to  have  wished  to  say  anything  which  might  be 
displeasing  to  him,  and  to  have  sought  to  misrepresent  facts, 
with  a  view  to  attribute  to  my  father  a  discovery  which  did 
not  belong  to  him ;  in  this  respect  Mr.  Daniell  is  strangely 
mistaken  as  to  my  intentions,  and  without  this  motive,  I  should 
not  have  replied  to  him,  having  nothing  to  change,  with  re- 
spect to  the  main  point,  in  the  facts  which  I  mentioned  in  my 
notice. 

In  every  physical  question  three  things  are  to  be  considered ; 
the  idea,  the  principle,  and  the  applications.  Now,  it  is  proved 
by  undoubted  facts,  that  from  1829,  and  even  several  years 
before,  my  father  had  invented  and  constructed  constant  vol- 
taic batteries,  which,  in  truth,  had  not  the  power  of  action 
and  the  advantages  possessed  by  the  constant  voltaic  batteries 
of  Mr.  Daniel],  who  made  them  known  in  1836.  The  ap- 
paratus invented  by  my  father  at  once  received  the  denomina- 

*  From  the  Ann.  de  Chim.  et  de  Phys.  for  August  1842  (Third  Series, 
vol.  v.  p.  412),  published  towards  the  end  of  September. 

Phil.  Mag.  S.  3.  Vol.  21.  No.  139.  Nov.  1842.        Z 


330  M.  Edmond  Becquerel  on  the  Constant 

tion  of  constant  voltaic  batteries  (appareils  a  courant  constant), 
and,  as  they  still  perfectly  fulfil  the  purpose  he  had  intended, 
it  is  impossible  to  contend  with  him  for  the  idea,  the  principle, 
or  the  application  within  certain  limits. 

The  details  into  which  I  shall  enter  will  leave  no  doubt 
about  the  priority  of  invention,  at  least  I  hope  so.  For  more 
than  fifteen  years  the  electro-chemical  reactions,  by  means  of 
which  my  father  was  enabled  to  obtain  crystallized  mineral 
substances,  were  produced  by  the  aid  of  small  apparatus  com- 
posed of  tubes  in  the  form  of  the  letter  U,  closed  at  their  cur- 
vature by  a  partition  of  moist  clay  designed  to  separate  the 
two  liquids  placed  in  the  two  branches  of  each  tube,  one  of 
which  contained  a  solution  of  sulphate,  nitrate  or  chloride  of 
copper  in  contact  with  a  plate  of  copper,  and  the  other  con- 
tained a  solution  of  sea-salt,  into  which  a  plate  of  zinc  or  of 
another  metal  was  immersed.  Such  is  the  arrangement  of 
the  simple  apparatus  which  is  scientifically  known  by  the 
name  of  pile  a  cloison*. 

The  form  of  this  apparatus  is  of  little  importance,  since  it 
may  be  infinitely  varied :  for  example,  instead  of  a  tube  in 
the  form  of  a  U,  we  may  take  any  kind  of  vessel,  separated 
into  two  compartments  by  a  diaphragm  of  bladder,  baked 
earth,  plaster,  or  linen,  &c.  But  all  these  various  modifica- 
tions enter  into  the  principle  of  the  U-tube. 

After  the  year  1829,  and  before  Mr.  DanielPs  publication, 
my  father  made  several  communications  relating  to  the  same 
subject ;  in  fact,  we  find  in  the  Compte  Rendu  des  Seances  de 
VAcademie  des  Sciences  for  1835,  the  description  of  an  appa- 
ratus giving  a  current  which  was  sensibly  constant  for  two 
entire  days. 

According  to  this,  therefore,  Mr.  Daniell  cannot  pretend 
to  the  discovery  of  the  general  principle  on  which  the  con- 
struction of  constant  voltaic  batteries  rests,  but  he  may  justly 
claim  the  good  arrangement  which  he  has  given  to  his  pile, 
and,  amongst  others,  the  advantage  of  always  having  a  satu- 
rated solution  of  sulphate  of  copper,  and  of  obtaining  in  a 
small  compass  effects  far  more  energetic  than  those  for  which 
my  father  had  occasion  in  the  beginning,  for  the  production 
of  crystallized  substances  analogous  to  those  formed  by  na- 
ture, a  discovery  for  which  he  received  the  Copley  Medal  from 
the  Royal  Society  of  London,  and  which  Mr.  Daniell  himself 
received  some  time  after  for  the  constant  voltaic  battery. 

Mr.  Daniell,  notwithstanding  facts  so  evident,  declares  in  his 

*  An  English  translation  of  the  description  of  this  apparatus,  and  of 
M.  Becquerel's  Researches  on  Crystallization  produced  by  Voltaic  Action, 
was  published  in  Taylor's  Scientific  Memoirs,  Part  3.  Jan.  1837. — Ed. 


Voltaic  Battery,  in  Reply  to  Mr.  Daniell.  331 

answer  that  he  was  not  guided  by  the  works  of  his  predecessors 
in  the  construction  of  his  battery,  and  that  the  principles  upon 
which  it  rests  are  different  from  those  which  my  father  had 
long  since  admitted.  He  states,  for  example,  that  the  rapid 
diminution,  as  well  as  the  definitive  cessation  of  the  cur- 
rent in  ordinary  batteries,  are  due  to  the  deposition  of  zinc 
on  the  negative  plates  of  each  couple.  "We  agree  perfectly 
upon  this  point;  the  annihilating  action  produced  by  the 
presence  of  the  zinc  comes  under  that  designated  by  the  term 
polarization  of  the  electrodes.  In  my  Notice,  indeed,  I  men- 
tion, p.  438,  in  the  eighth  and  following  lines,  that  "  each 
negative  plate  (of  copper  or  of  platinum)  retains  on  its  sur- 
face alkaline  elements,  such  as  hydrogen  arising  from  the  de- 
composition of  water,  and  bases  arising  from  the  decomposi- 
tion of  saline  matters  dissolved  in  water."  This  phrase  does 
not  exclude  any  of  the  bases ;  the  zinc  therefore  arising  from 
the  decomposition  of  the  salt  of  zinc  must  equally  be  deposited 
on  the  negative  plate.  This  deposition  being  effected,  the 
action  of  the  liquid  on  the  zinc  necessarily  gives  birth  to  a 
counter- current  which  more  and  more  destroys  the  action  of 
the  first;  in  order  to  have  an  apparatus  of  continued  force,  it 
was  necessary  to  prevent  the  zinc  and  the  alkalies  from  being 
deposited  on  the  negative  electrodes. 

Mr.  Daniell  afterwards  says  that  the  passage  of  the  electric 
current  across  diaphragms  of  bladder  is  well  known  to  expe- 
rimentalists;  he  quotes  Dr.  Ritchie  as  having  made  use  of 
them.  To  which  I  reply,  that  the  use  of  diaphragms  in  physics 
is  very  ancient,  since  one  of  the  Bernoullis  had  already  se- 
parated two  different  liquids  by  a  membrane,  in  an  experi- 
ment in  which  he  wished  to  produce  an  effect  of  endosmose. 
Porrett  also  adopted  the  same  expedient  in  order  to  show 
that  in  separating,  by  means  of  a  membrane,  a  mass  of  water 
into  two  parts,  into  each  of  which  a  plate  of  platinum  was 
plunged  communicating  with  one  of  the  poles  of  a  battery 
pile,  the  water  passed  from  the  positive  into  the  negative 
compartment.  1  might  still  quote  other  examples ;  but  the 
use  of  membranes,  of  diaphragms  permitting  the  current  to 
pass  in  order  to  obtain  a  couple  giving  a  constant  current, 
was  brought  into  use  by  my  father  nine  or  ten  years  before 
Mr.  Daniell  was  occupied  with  this  question,  and  particularly 
in  the  experiments  communicated  to  the  Academie  des  Sciences 
on  the  23rd  of  February,  1829*. 

As  to  the  publication  of  Dr.  Ritchie  in  the  Philosophical 
Transactions,  it  is  of  the  month  of  May  1829,  and  conse- 
quently some  months  later,  I  therefore  look  upon  Mr.Daniell's 

*  Ann.  de  Vhys.  et  de  Chimie,  t.  xli. 
Z2 


332     M.  Edmond  Becquerel  in  Reply  to  Mr.  Daniell. 

pile,  although  very  convenient,  as  based  upon  the  same  prin- 
ciples as  the  apparatus  which  my  father  has  used  for  a  long 
time. 

Further  on  Mr.  Daniell  adds :  "  Even  in  the  use  of  the 
diaphragm,  which  might  at  first  sight  appear  similar,  there  is 
a  direct  opposition,  for  my  object  is  to  keep  the  two  electro- 
lytes which  I  employ  perfectly  separate,  so  that  no  portion 
of  one  may  penetrate  to  the  other,  except  in  the  process  of 
electrolysis." 

I  confess  that  I  know  not  how  Mr.  Daniell  can  separate 
two  liquids  by  a  membrane  moistened  by  them  and  which 
they  can  penetrate,  without  that  passage  from  one  to  the  other 
taking  place  which  is  otherwise  called  endosmose  and  exos- 
mose.  It  is  impossible  to  realize  this  condition;  the  only 
means  of  retarding  for  as  long  a  time  as  possible  the  mixture 
of  the  two  liquids,  is  by  substituting  for  the  membrane  a  thick 
diaphragm  of  clay,  as  did  my  father;  the  intensity  of  the  cur- 
rent is  then  diminished,  but  constant  effects  are  obtained 
which  may  continue  for  months,  for  years. 

Still  further  on  Mr.  Daniell  says :  "  and  I  repeat,  that  in 
my  constant  battery  nothing  depends  upon  the  contact  and 
action  of  the  two  liquids  upon  each  other." 

I  do  not  understand  this  assertion;  for  every  one  knows  that 
two  different  liquids  acting  upon  each  other  by  an  intermedial 
membrane,  disengage  electricity  enough  to  produce  a  current ; 
and  if  Mr.  Daniell  wishes  to  convince  himself  of  it,  he  has 
only  to  take  away,  in  one  of  his  couples,  the  plate  of  zinc  and 
that  of  copper,  and  to  substitute  two  plates  of  platina  for  them  ; 
he  will  have  a  current  owing  to  the  reaction  of  the  two  liquids 
upon  each  other,  less  intense  indeed  than  that  obtained  with 
a  couple  in  which  an  oxidable  metal  is  included. 

Mr.  Daniell  also  says,  that  "  the  amount  of  force  obtained 
by  my  father's  apparatus  is  insignificant  with  regard  to  its  ap- 
plication to  the  arts." 

I  will  reply  yes  and  no  to  him;  yes,  if  there  is  a  question 
of  apparatus  like  those  of  Mr.  Daniell,  designed  to  obtain  cur- 
rents which  are  to  be  transmitted  into  liquids  placed  in  se- 
parate vessels;  no,  if  the  currents  are  to  react  chemically  on 
the  liquids  making  a  part  of  the  apparatus  themselves. 

In  short,  the  apparatus  constructed  by  my  father,  six  years 
ago,  for  the  treatment  of  ores  of  silver  of  lead  and  of  copper, 
are  based  on  the  same  principles  whioh  I  have  before  ex- 
plained, and  are  of  much  more  considerable  dimensions  than 
those  of  Mr.  Daniell,  since  each  couple  requires  1000  litres 
of  liquid  to  act,  and  six  similar  couples  have  been  united, 
so  that  6000  litres  have  acted  at  the  same  time,   and  the 


Prof.  Grove's  Remarks  on  a  Letter  o/Prof.  Daniell.     333 

energy  of  action  has  been  still  greater  than  that  produced 
with  the  apparatus  of  Mr.  Daniell,  since  all  the  silver  and  the 
lead  contained  in  the  ores,  that  is  to  say  about  one  kilogramme 
of  silver  and  100  kilogrammes  of  lead,  were  extracted  in  the 
space  of  a  few  hours. 

I  now  leave  it  to  the  judgement  of  the  reader  which  is  in  the 
right,  Mr.  Daniell  or  myself;  and  it  will  then  be  seen  whether 
Jilial  piety  blinded  me,  or  whether  I  have  not  rather  been 
actuated  by  the  love  of  truth. 
Paris,  July  7, 1842. 

LVI.  Remarks  on  a  Letter  of  Professor  Daniell  contained  in 
the  Philosophical  Magazine  for  April.  By  W.  R.  Grove, 
Esq.,  M.A.f  F.R.S.,  Professor  of  Experimental  Philosophy 
in  the  London  Institution. 

To  the  Editors  of  the  Philosophical  Magazine  and  Journal. 
Gentlemen, 

A  LLO  W  me  to  request  your  insertion  of  a  few  remarks  on 
■£*-  a  letter  of  Professor  Daniell  published  in  your  Magazine 
for  April.  Absence  from  London  and  occupations  of  other 
than  a  scientific  nature  prevented  my  noticing  it  at  the  time ; 
my  attention  has  been  recalled  to  the  matter  by  its  republi- 
cation in  the  Annales  de  Chimie. 

A  few  words  at  the  conclusion  of  this  letter  refer  to  me : 
after  stating  that  M.  Becquerel  has  inadvertently  described 
my  experiments  as  anterior  to  Mr.  DanielFs,  this  gentleman 
goes  on  to  say,  "  Professor  Grove  has  never  spoken  of  his 
battery  but  as  the  further  application  of  principles  which  I 
had  previously  deduced." 

It  is  perhaps  of  little  moment  to  the  public  what  principles 
led  me  to  the  construction  of  the  battery  in  question,  but  it 
may  be  of  some  moment  to  me,  as  should  I,  by  silence,  be  held 
to  assent  to  certain  principles,  I  may  be  accused  of  contradic- 
tion and  inconsistency  if  in  any  future  paper  I  should  state 
my  adherence  to  others.  M.  Becquerel,  again,  in  the  5th 
volume  of  his  Traite  de  V Electricite,  describes  my  battery  as 
"  Pile  voltaique  construite  d'apres  les  principes  exposes 
dans  les  chapitres  ler,  &c .:"  these  chapters  contain  the  papers 
of  M.  Becquerel  in  respect  of  which  he  claims  priority  to 
Mr.  Daniell.  It  is  obvious,  that  as  M.  Becquerel  and  Mr. 
Daniell  differ  in  their  notions  as  to  the  principles  of  the  con- 
stant battery,  I  could  not  derive  my  battery  from  both,  and 
I  have  looked  over  my  papers  on  this  subject  to  see  whether 
I  have  expressly  referred  it  to  principles  enounced  by  either 


334-    Prof.  Grove's  Remarks  on  a  Letter  of  Prof.  Daniell. 

of  these  philosophers ;  I  cannot  see  that  I  have.  I  have  on 
many  occasions  mentioned  their  experiments  before  my  own 
in  the  history  of  the  voltaic  pile,  both  as  acknowledging  their 
priority  and  as  not  wishing  to  claim  what  was  not  my  due ; 
probably  it  is  this  which  has  led  to  a  misconception  on  the 
part  of  Mr.  Daniell,  but  I  have  distinctly  stated  the  idea 
which  immediately  led  to  the  construction  of  my  battery  in  the 
paper  which  describes  it  (Phil.  Mag.,  May  1839).  After  de- 
tailing an  experiment  with  two  strips  of  gold-leaf  in  nitric  and 
hydrochloric  acids  separated  by  a  porous  diaphragm,  and 
showing  that  upon  contact  of  the  two  strips  the  gold  in  the 
hydrochloric  acid  was  dissolved,  and  that  a  voltaic  current 
was  established,  I  say,  "  It  now  occurred  to  me,  that  as  gold, 
platina  and  two  acids  gave  so  powerful  an  electric  current,"  a 
fortiori  "  the  same  arrangement,  with  the  substitution  of  zinc 
for  gold,  must  form  a  combination  more  energetic  than  any 
yet  known :"  this  was  the  simple  deduction  which  led  to  my 
subsequent  experiments.  I  have  in  most  cases  been  content 
to  publish  experiments  with  no  more  of  theory  than  was  re- 
quisite to  connect  them ;  it  is  a  general  and  I  think  a  just  com- 
plaint that  there  are  already  too  many  speculations  on  this  sub- 
ject ;  but  in  a  letter  published  in  the  Philosophical  Magazine 
for  Feb.  1839,  p.  129,  previous  to  the  discovery  of  my  battery, 
I  gave  my  own  notions  of  the  principles  of  voltaic  batteries, 
notions  which  in  some  respects  agree  with  those  of  Mr. 
Daniell,  but  which  also  suggest  some  new  views  of  voltaic  ac* 
tion.  There  is  one  experiment  there  detailed  in  which  copper 
is  reduced  by  copper,  which  had  much  influence  on  my  subse- 
quent experiments,  but  which  is  not  explicable  by  any  prin- 
ciples laid  down  by  Mr.  Daniell;  at  the  conclusion  of  this 
paper  I  say,  "  if  these  principles  be  correct,  very  superior 
combinations  may  be  discovered:"  how  this  prediction  has 
been  fulfilled  the  public  is  the  best  judged 

Far  be  it  from  me  to  disclaim  any  assistance  from  the  ex- 
periments of  Mr.  Daniell  or  of  M.  Becquerel;  I  shall  ever  re- 
tain a  grateful  recollection  of  the  assistance  rendered  to  my 
first  efforts  in  science  by  the  latter  gentleman.  I  cannot  at  this 
distance  of  time  well  describe  what  effect  their  experiments 
had  upon  my  mind.  In  the  progress  of  science  it  is  difficult 
to  define  the  frequently  unperceived  effect  of  prior  discoveries 
upon  subsequent  experimentalists,  but  I  cannot  for  many  rea- 
sons acquiesce  in  the  assertion  of  Mr.  Daniell  above  quoted. 

Mr.  Daniell  was  for  a  long  time  attached  to  the  theory  of 
the  deposition  of  metals  in  the  voltaic  circuit  being  the  result 
of  a  secondary  action  of  the  nascent  hydrogen,  a  theory  ge- 
nerally adopted  until  combated  by  Hisinger  and  Berzelius ;  thus 


Prof.  Grove's  Remarks  on  a  Letter  of  Prof.  Daniell.    335 

in  his  papers,  Phil.  Trans.,  1836,  p.  117  etseq.,  he  proceeds  to 
explain  his  constant  battery  as  dependent  upon  the  removal 
of  that  hydrogen  by  causing  it  to  deoxidate  copper:  in  a 
subsequent  publication  (Phil.  Trans.,  1839)  he  abandons  this 
view,  and  considers  the  deposition  of  the  copper  as  "  a  primary 
result  of  electrolytic  action."  This  would  altogether  alter 
the  theory  of  his  battery  and  of  mine.  I  do  not  think  it  is  a 
matter  of  great  consequence  which  theory  be  adopted ;  each  • 
has  many  peculiar  difficulties,  each  tends  to  many  similar 
conclusions,  and  either  may  lead  to  equally  successful  experi- 
mental results.  Theory  is  valuable  as  a  means  not  as  an  end, 
and  that  theory  of  the  voltaic  battery  is  in  my  opinion  the 
best  which  best  collates  the  observed  phaenomena  and  which 
leads  to  the  discovery  of  the  best  voltaic  combinations.  But 
although  I  would  hesitate,  without  more  conclusive  experi- 
ments, in  ascribing  this  superiority  to  either  of  these  theories, 
there  is  another  principle  of  the  voltaic  battery  enounced  by 
Mr.  Daniell,  as  to  which,  so  far  from  agreeing  with  him,  I  must 
take  leave  (with  every  respect  for  his  scientific  attainments) 
to  differ  toto  ccelo :  it  is  as  to  the  relative  extent  of  surface  to 
be  given  to  the  metals  of  voltaic  combinations.  Mr.  Daniell 
has  in  the  Phil.  Trans,  for  1836,  p.  128,  and  in  several  subse- 
quent papers,  stated  that  the  best  theoretical  form  for  a  voltaic 
combination  is  when  the  generating  metal  is  arranged  with 
regard  to  the  conducting  one  as  the  centre  of  a  sphere  to  its 
periphery,  and  recommends  a  rod  within  a  cylinder  as  the 
nearest  practical  approximation  to  such  an  arrangement ;  fol- 
lowing the  authority  of  Mr.  Daniell,  I  first  constructed  my 
batteries  of  this  form,  but  very  soon  abandoned  it  (see  Phil. 
Mag.  forOct.1839,  p.  288) ;  and  1  am  now  convinced,  by  three 
years'  experience  and  by  repeated  experiments,  corroborated 
by  the  experiments  of  others,  that  this  is  by  no  means  the  best 
form  of  arrangement,  as  regards  ceconomy  either  of  space, 
time,  or  material.  I  believe  the  old  arrangement  of  equal  sur- 
faces to  be  sufficient  for  most  practical  purposes ;  but  the  relative 
size  may  be  considerably  modified  according  to  the  nature  of 
the  electrolytes,  the  conducting  power  of  the  metals,  and  other 
circumstances.  I  cannot  enter  more  fully  on  this  point  without 
writing  a  paper  especially  on  this  subject. 

P.S.  Since  the  above  was  written  I  have  received  a  paper 
of  Mr.  Daniell's  just  printed,  Phil.  Trans.  1842,  part  ii.,  for 
which  I  have  to  thank  the  author :  it  contains  a  series  of  ex- 
periments on  my  battery,  and  with  a  voltameter  of  my  con- 
trivance. In  this  paper  I  see  Mr.  Daniel  alters  many  of  his 
opinions  upon  the  relative  size  of  the  plates  in  voltaic  com- 
binations. 


[     336     ] 

LVII.  On  the  Iodide  of  Mercury.     By  H.  F.  Talbot,  Esq.. 

F.R.S. 
To  the  Editors  of  the  Philosophical  Magazine  and  Journal. 
Gentlemen, 

YOUR  Number  for  last  September  contains  a  paper  by  Mr. 
Warington  "  On  the  Change  of  Colour  in  the  Biniodide 
of  Mercury."  Permit  me  to  observe,  that  the  facts  contained 
in  the  first  part  of  that  paper  were  long  ago  discovered  and 
published  by  myself,  in  your  Journal  (S.  3.  vol.  ix.  p.  2*). 

As  I  do  not  wish  to  be  deprived  of  the  discovery  of  one  of 
the  most  curious  phaenomena  in  optics,  I  beg  leave  to  draw 
Mr.  Warington's  attention  to  that  paper,  and  briefly  to  re- 
capitulate its  contents. 

In  that  memoir  I  have  shown, — 

1.  That  when  iodide  of  mercury  is  sublimed  between  two 
plates  of  glass  nearly  in  contact  with  each  other,  it  cools  in 
the  form  of  thin  rhombic  plates  of  a  pale  yellow  colour. 

2.  These  often  retain  their  colour  when  cold,  if  left  undis- 
turbed. 

3.  But  if  such  a  crystal  is  disturbed,  as  for  example,  by 
touching  it  with  a  needle  at  any  point  of  its  surface,  it  in- 
stantly turns  scarlet  at  the  point  touched,  and  the  scarlet  co- 
lour is  rapidly  propagated  over  the  whole  crystal.  I  showed 
this  experiment  to  Sir  David  Brewster  in  the  year  1836,  and 
I  have  no  doubt  he  remembers  it  well,  as  he  expressed  great 
admiration  of  the  beauty  of  the  phenomenon.  The  crystal 
was  touched  with  the  needle  while  under  examination  with  a 
powerful  microscope. 

4.  The  crystal  moves  and  is  spontaneously  agitated  during 
the  time  it  is  changing  colour. 

5.  During  the  progress  of  this  change,  the  scarlet  portion 
remains  bounded  by  straight  lines,  very  well  defined,  and  par- 
allel to  the  edges  of  the  rhombic  crystal. 

6.  I  thence  drew  the  conclusion,  that  the  change  of  colour 
was  caused  by  the  displacement  of  the  rows  of  molecules  or 
laminae  of  the  crystal.  This  I  think  will  be  admitted  to 
be  the  true  explanation ;  and  it  was  one  which  h  ad  not  been 
previously  suggested.  I  added,  that  I  thought  this  phenome- 
non "  the  most  evident  proof  we  yet  possessed  of  the  dependency 
of  colour  upon  internal  molecular  arrangement" 

7.  I  also  remarked  that  these  little  rhombic  crystals  were 
very  fine  objects  for  the  polarizing  microscope.  The  expres- 
sions of  Mr.  Warington,  that  the  crystals  "  in  the  dark  f eld 
had  the  appearance  of  the  most  splendid  gems"  have  recalled 

[•  On  inserting  Mr.  Warington's  paper  we  referred  to  Mr.Talbot's  pre- 
vious experiments,  as  stated  by  him  in  Phil.  Mag. — Edit.] 


On  the  Progress  of  Embryology  in  the  Year  1840.        337 

to  my  memory  the  very  similar  words  which  I  used  when  I 
first  announced  the  invention  of  the  polarizing  microscope  in 
your  Journal  (vol.  v.  p.  324),  viz. 

"  The  field  of  view  appears  scattered  with  the  most  brilliant 
assemblage  of  highly  coloured  gems,  affording  one  of  the 
most  pleasing  sights  that  can  be  imagined.  The  darkness  of 
the  ground  on  which  they  display  themselves  greatly  en- 
hances the  effect." 

With  regard  to  the  above  points,  then,  I  consider  that  they 
were  sufficiently  established  by  me  in  1836. 

The  second  part  of  Mr.  Warington's  paper,  however,  con- 
tains a  fact  both  new  and  important ;  I  mean  the  solution  of 
the  yellow  crystals  in  the  liquid  and  the  formation  of  the  red 
ones,  of  a  different  form,  in  their  places.  But  this  observa- 
tion is  most  strictly  analogous  to  the  phenomenon  which  I 
discovered  in  the  iodide  of  lead,  and  published  in  your  Journal 
(vol.  ix.  p+405),  viz.  the  sudden  change  of  a  crystal  of  that 
salt  from  the  form  of  a  white  needle  to  that  of  a  row  of  thin 
yellow  regular  hexagons  lying  in  a  straight  line.  Such  a  me- 
tamorphosis was  previously  unexampled ;  Mr.Warington  has 
now  furnished  us  with  a  second  example  (also  the  iodide  of 
a  metal) :  I  have  myself  observed  something  similar  in  the 
iodide  of  tin ;  and  I  recommend  the  whole  subject  of  the  cry- 
stalline form  of  the  metallic  iodides  to  the  renewed  and  care- 
ful consideration  of  chemists. 

I  am  glad  of  the  opportunity  afforded  me  by  Mr.  Waring- 
ton's paper  of  again  calling  attention  to  these  very  curious 
facts,  which  appear  to  me  to  open  a  path  that  promises  to  lead 
far  into  those  arcana  of  Nature,  the  mysteries  of  molecular 
action. 

I  remain,  Gentlemen,  yours,  &c, 

London,  Oct.  1,  1842.  H.  F.  TALBOT. 

LVIII.  On  the  Progress  of  Embryology  in  the  Year  1S40*. 

"  COME  interesting  discoveries  rendered  the  past  year  a 
highly  productive  one  for  embryology.  Two  main  pro- 
blems which  engaged  the  various  physiologists  here  occupy 
the  foreground,  namely,  the  earliest  development  of  the  Mamr 
malia,  and  the  metamorphoses  of  the  germinal  membrane  in  its 
transformation  into  the  embryo******.  So  long  as  the  meta- 
morphoses of  the  germinal  vesicle  following  fecundation  could 
be  considered  only  hypothetically,  it  was  assumed  that  the  Pur- 
kinjean  [germinal]  vesicle  either  burst  and  poured  out  its  con- 
tents, or  became  flattened ;  and  now  contributed  to  the  forma- 

*  From  Professor  Valentin's  Report  in  the  Repertorium  fur  Anatomie 
und  PJjysiologie,  Jahrgang  1841. 


338       On  the  Progress  of  Embryology  in  the  Year  1840. 

tion  of  the  germinal  membrane  in  one  of  these  two  ways.  Both 
theories  had  been  put  forth  before  the  discovery  of  the  germinal 
spot.  But  when  the  existence  of  the  latter  became  known, 
the  discoverer  of  the  same  said  that  probably  the  macula 
germinativa  represented  the  first  foundation  of  the  germinal 
membrane.  This  conjecture  obtained  more  probability  from 
the  obvious  fact,  that  the  number,  size  and  distribution  of  the 
germinal  spots  alternated  according  to  the  different  stages. 
Research,  however,  first  in  the  Mammalia,  and  then  in  Rep- 
tiles and  Fishes,  showed  that  in  consequence  of  fecundation 
the  interior  of  the  germinal  vesicle  presents  new  cells,  or  that 
(as  was  seen  in  the  Rabbit)  within  the  germinal  vesicle  new 
cells  are  really  built  up  upon  the  foundation  of  the  germinal 
spots."  (Introductory  Remarks,  p.  13.) 

First  stages  in  the  development  of  the  fecundated  ovum,  espe- 
cially that  of  the  Mammalia.  As  was  already  remarked  in  the 
introduction,  the  most  important  publications  of  the  past  year 
concerning  embryology  are  concentrated  in  the  subjects  of 
this  chapter.  We  will  therefore,  before  presenting  some  ex- 
tracts of  the  details,  state  the  most  important  results.  With 
few  exceptions,  to  be  mentioned,  all  the  observations  have  re- 
ference to  the  Mammalia,  and  indeed  to  the  Rabbit. 

1.  At  the  period  of  the  rut  certain  changes  have  already 
taken  place  in  the  ovarium,  the  [Graafian]  follicles,  and  the 
structures  appertaining  thereto.  Through  an  increased  con- 
gestion of  the  ovary  single  follicles  become  more  strongly  de- 
veloped. The  germinal  spot,  which  gives  the  impulse  to  the 
formation  of  the  new  cells,  probably  undergoes  changes  of 
this  kind.  From  the  observations  of  Negrier,  above  men- 
tioned (p.  248),  it  may  be  conjectured  that  in  the  human  fe- 
male also  the  period  of  menstruation  is  attended  by  similar 
phaenomena. 

2.  Fecundation  itself  apparently  comes  to  pass  in  the  following 
manner:  a  portion  of  the  semen  that  has  been  brought  to  the 
surface  of  the  ovarium  probably  passes  into  the  ovum,  and 
gives  the  stimulus  to  the  formation  of  cells  within  the  germinal 
vesicle******. 

3.  The  number  of  ova  prepared  for  fecundation  by  the  rut, 
does  not  correspond  with  the  number  of  the  subsequently  fecun- 
dated ova,  but  generally  exceeds  the  same.  This  fact,  already 
known,  has  been  confirmed  by  the  latest  researches  on  the 
Rabbit. 

4.  It  often  happens  that  more  ova  pass  out  of  the  ovary  than 
are  fecundated,  or  at  least  than  become  developed.  Herein  ac- 
cord the  observations  of  Barry  with  those  of  Pappenheim. 
The  former  found  in  the  tubes  and  uterus  unfecundated  or 


On  the  Progress  of  Embryology  in  the  Year  1840.      339 

aborted  ova.  In  like  manner,  parts  of  the  [Graafian]  follicle 
which  usually  remain  in  the  ovary,  for  example,  portions  of 
Barry's  ovisac,  may  be  found  in  the  oviducts. 

5.  Neither  the  place  to  which  the  ova  in  the  tubes  and  uterus 
have  advanced,  nor  the  size  of  the  same,  nor  the  time  that  has 
elapsed  since  they  left  the  ovary,  affords  an  exact  criterion  for 
the  degree  of  their  internal  development.  This  position  fur- 
nishes only  a  confirmation  of  what  was  already  known******. 

6.  The  germinal  vesicle  does  not  disappear  nor  burst  through 
fecundation,  but  fills  with  cells,  the  formation  of  which  proceeds 
from  the  germinal  spot :  and  this  takes  place  by  no  means  in  a 
peculiar  manner,  but  according  to  a  normal  mode  which  mani- 
fests itself  elsewhere.  These  circumstances,  which  really  ex- 
tend our  knowledge,  have  been  made  known  by  the  laborious 
researches  of  Barry.  The  general  process  is  as  follows; — It  is 
known  that  in  the  interior  of  the  germinal  spot  there  exists  a 
central  body,  which  often  becomes  surrounded  by  concentric 
traces.  This  body  now  enlarges  and  fills  with  a  pellucid  fluid. 
That  part  of  the  germinal  spot  which  is  directed  towards  the 
interior  of  the  germinal  vesicle  passes  into  cells,  arranged 
like  pill-boxes  one  within  the  other,  yet  so  that  the  pellucid 
central  vesicle  remains  near  to  the  periphery  [of  the  ovum]. 
Within  the  cells  thus  arisen  there  are  formed  new  cells.  This 
cell-formation  proceeds  in  layers  from  the  centre  towards  the 
periphery.  The  outer  strata  of  cells  are  thus  pushed  further 
out,  and  the  most  external  disappear  while  new  inner  strata 
form,  so  that  the  middle  ones  advance  to  the  outer  part.  In 
this  manner  the  germinal  vesicle  becomes  filled  with  masses 
of  cells,  while  its  membrane  disappears.  But  in  the  situation 
of  what  was  originally  the  centre  of  the  germinal  spot  there 
are  formed  two  cells,  distinguished  by  their  larger  size :  and 
out  of  these  two  larger  cells  new  cells  arise,  as  before  through 
the  formation  of  cells  in  cells, — 4,  8,  16,  and  so  on, — the  num- 
ber doubling  every  time.  These  two  cells  of  the  central  part 
of  the  germinal  spot,  with  their  succeeding  cells,  form  the 
foundation  of  the  germ.  In  it,  the  germ,  again,  there  is  to 
be  seen  a  cell  distinguished  by  its  larger  size.  The  nucleus 
of  this  latter  cell  generates,  through  further  development,  the 
foundation  of  the  embryo.  It  may  hence  be  conceived,  that 
the  seminal  fluid  taken  up  by  imbibition,  arrives  at  what  was 
originally  the  central  part  of  the  germinal  spot ;  first  gives  a 
stimulus  to  the  cell-formation  in  the  peripheral  part  of  the 
germinal  spot,  and  to  the  consequences  of  the  same ;  then, 
through  the  formation  of  cells,  becomes  itself  the  germ ;  and 
that,  subsequently,  within  the  germ  the  nucleus  of  a  principal 
cell  gives  the  stimulus  to  the  formation  of  the  embryo.     Fe- 


S40      Mr.  Earnshaw  in  Reply  to  Prof.  Kelland  on  the 

cundation  thus  consists  in  the  imbibed  seminal  fluid  stimulating 
the  germinal  spot  to  the  cell-formation,  according  to  the  type 
of  cells  in  cells.  But  many  more  cells  are  formed  than  re- 
main ;  the  outer  layers  being  constantly  absorbed. 

7.  The  furrows  known  to  be  presented  by  the  yelk  arise  from 
the  formation  of  cells  (see  Repertorium,  v.  306).  Their  pre- 
sence in  Fishes  was  etablished  by  Rusconi,  in  Mammals  by 
Barry.  In  Birds  they  may  either  entirely  fail,  or,  as  is  more 
probable,  be  limited  to  the  germinal  membrane  and  not  ex- 
tended to  the  yelk. 

8.  The  rotation  of  the  yelk  or  of  the  embryo  in  the  ovum,  pre- 
viously observed  in  invertebrated  animals  and  in  Batrachian 
Reptiles,  is  also  found  to  take  place  in  Fishes  and  Mammalia. 
Rusconi  perceived  this  rotation  thirty  hours  after  fecundation 
in  ova  of  the  Pike ;  so  that  it  is  thus]  met  with  where  there 
is  a  circumscribed  germinal  membrane.  In  the  Rabbit  it  was 
seen  by  Barry,  although  he  remained  in  doubt  as  to  the  na- 
ture of  the  rotating  body  which  was  determined  by  Bischoff. 
The  latter  described  also  vibrating  cilia  on  the  superficial 
cells.  It  now  remains  a  point  of  especial  interest,  to  extend 
the  observation  to  classes  which  otherwise  do  not  exhibit  ci- 
liary motion,  for  instance  the  Crustacea. 

9.  Of  the  other  structures  of  the  [Graafian]  follicle  which 
pass  out  [of  the  ovary]  along  with  the  ovum,  the  tunica  granulosa 
and  retinaada  {discus  proligerw)  undergo  liquefaction ;  while 
within  the  zona  there  arise  concentric  formations  of  membranes 
andfuid  or  semifluid  rings.  According  to  Barry,  this  forma- 
tion amounts  to  from  four  to  five  membranes.  The  attenua- 
tion of  the  zona  above  mentioned  soon  disappears.  The  chorion 
is  not  formed  out  of  the  zona,  but  out  of  cells,  which  arise  in 
the  tube  and  are  laid  down  around  the  metamorphosed  struc- 
tures. 

[Professor  Valentin  then  proceeds  to  give  details  of  the  ob- 
servations of  Dr.  Barry,  the  principal  of  which  are  the  fore- 
going nine.  These  details  will  be  found  in  the  Philosophical 
Transactions  for  1839  and  1840.  Abstracts  of  them  have 
been  already  furnished  by  this  Journal.] 

LIX.    On  the  Theory  of  Molecular  Action  according  to  New- 
ton's Law:  in  reply  to  Professor  Kelland.     By  S.  Earn- 
shaw, M.A.,  Cambridge  *. 
TJTAVING  been  long  of  opinion  that  the  molecular  forces 
•*■      which  regulate  the  vibratory  motions  of  particles  cannot 
vary  according  to  Newton's  law  of  universal  gravitation,  it 
*  Communicated  by  the  Author. 


Theory  of  Molecular  Action  according  to  Newton's  Law.  341 

was  with  great  pleasure  that  I  read  in  Professor  Kelland's 
letter  that  the  attention  of  the  greatest  mathematicians  in  Eu- 
rope is  now  alive  to  the  necessity  and  importance  of  having 
"  the  difficulties  which  attend  the  theory"  removed:  and  I 
rejoice  that  Professor  Kelland  has  undertaken  the  task  of 
thoroughly  reviewing  the  grounds  of  my  opinion.  In  my 
memoir  on  the  subject  printed  in  the  Cambridge  Philosophical 
Transactions,  I  have  shown,  apparently  to  Professor  Kelland's 

^«V     d2V      dV 
satisfaction,  that  when  -,  f2  >     ,■  2-,  —  ,  rt  are  not  zero,   the 

medium  is  incapable  of  transmitting  light,  and  have  dismissed 
at  once  as  foreign  to  the  subject  the  case  where  these  quan- 
tities are  zero,  which  case  the  Professor  argues  "  embodies 
the  real  state  of  things."  The  grounds  on  which  I  dismissed 
this  case  in  so  summary  a  manner  were  these : — 

1st.  The  acknowledged  experimental  fact  of  the  superpo- 
sition of  waves  of  light  requires  that  the  forces  called  into 
play  by  a  displacement  should  depend  only  (or  at  any  rate 
chiefly)  on  the^r^  power  of  the  displacement. 

2ndly.  The  received  explanations  of  refraction  through  cry- 
stals and  of  other  pheenomena,  assume  that  the  force  of  restitu- 
tion depends  only  on  the^r^  power  of  the  displacement ;  and, 

3rdly.  If  -tj^ >    ,   2  ?  ~JW      zero>tne  nrst  powers  ol  the 

displacement  disappear ;  and  therefore  this  case  is  inconsist- 
ent with  the  known  results  of  experiment  and  the  require- 
ments of  received  and  established  theory.  Yet  Professor 
Kelland  thinks  that  the  real  state  of  things  is  embodied  in  the 
excepted  case,  and  founds  his  belief  on  arguments  drawn  from 
analytical  expressions  in  his  memoir.  It  appears  to  me,  then, 
that  the  shortest  way  of  bringing  the  controversy  to  an  end, 
will  be  to  show  that  the  Professor's  own  investigations,  under 
proper  mangement,  lead  us  to  the  same  results  as  were  given 
in  my  memoir.  At  pages  162,  163  of  the  Professor's  paper 
on  Dispersion,  we  are  told  that  on  the  hypothesis  which  he 
has  adopted  each  of  the  quantities 

2X{^  +  ^8^}sin2/4i 
2s|*r+^83/2^sin2  ~ 


Q 


1   <p  r  ^ \-L  h2^  si"2 


is  equal  to  n\    It  follows  therefore  that  »2  is  equal  to  one 
third  of  their  sum,  i.  e. 


342        The  Rev.  M.  O'Brien's  Additional  Remarks 

sin2 


n2  =  —  %  l3<pr+r~Fr\ 


i 


The  quantity  n  is  the  coefficient  of  t  in  the  expression  of  a 
displacement,  a.  =  a  cos  (nt— kg), 

1  3 

Now  on  the  Newtonian  law  <t>  r  =  — o-    and  F  r  =  —  -3-, 

and  therefore  n*  =  0 ;  which  being  substituted,  the  Professor's 
equations  of  motion  assume  the  following  forms :  — 

d*a  d2/3  ^7 

d*2  ~  °'  ~dW~0i  IT  _0' 
which  indicate  that  on  the  Newtonian  hypothesis  no  forces  are 
called  into  play  by  the  vibratory  displacements  of  the  particles. 
Now  the  Professor,  having  treated  the  quantity  n2  as  finite  in 
all  his  investigations  on  this  subject,  will  see  that  all  argu- 
ments based  on  them  against  what  I  have  written  fall  to  the 
ground,  and  that  my  arguments  remain  in  full  force. 
Cambridge,  August  19, 1842. 

LX.  Some  Additional  Remarks  upon  a  Communication  of  Pro- 
fessor Kelland,  published  in  the  Philosophical  Magazine  for 
May  last.  By  the  Rev.  M.  O'Brien,  late  Fellow  of  Caius 
College,  Cambridge*. 

N  the  Philosophical  Magazine  for  June  1842,  I  asserted 
that  certain  fundamental  equations  in  Professor  Kelland's 
memoir  on  Dispersion  (in  the  Cambridge  Phil.  Trans.,  vol.  vi.) 
were  erroneous.  A  friend  has  suggested  to  me  that  I  ought 
to  have  proved  more  distinctly  the  existence  of  those  errors. 
This  I  will  now  do  in  the  following  manner: — 

(1.)  With  respect  to  the  equations  qf  motion  in  page  159,  vol. 
vi.  Camb.  Trans.  Professor  Kelland  has  overlooked  the  terms 
arising  from  the  part  of  the  equation  in  page  158,  which  is 
multiplied  by  S  /3  and  8  y :  for  instance,  there  is  a  term  in  the 

expansion  of  8  /3  (viz.  ^ — -r-lxly  \  which  gives  rise  to  the 

d?  a. 
following  term  in  the  expression  for  -j-^ ,  viz. 

r  J   dxdy 

which  term  does  not  appear  as  it  might  in  Professor  Kel- 
land's equation. 

And  there  is  another  similar  term  omitted,  viz. 

r  ax  dz 

*  Communicated  by  the  Author. 


I 


upon  a  Communication  of  Prof.  Kelland.  343 

(2.)  With  respect  to  the  equations  at  the  foot  of  page  162, 
we  have 

8g2  =  £Za*+f**ip+g*# 

+  <2.{eflxly  +fgly**  +  eglxlz). 

Hence  expanding  sin2  — -£-,  and  omitting  the  parts  multi- 

3S 

plied  by  F  k6,  &c.,  we  have 

omitting  all  terms  in  which  an  odd  power  of  either  8.r,  ly  or 
82  occurs. 

Hence  the  term  which  Professor  Kelland  makes  out  to  be 
zero,  equals 

ef~%  /Ce2  §  #2  $y\  +  higher  powers  of  h\ 

'which  is  clearly  not  zero. 

The  error  by  means  of  which  Professor  Kelland  shows 
that  this  term  is  zero,  is  quite  apparent  in  the  middle  of  page 
162.  He  reasons  upon  8  p  just  as  if  it  was  r,  i.  e.  the  distance 
of  the  particle  whose  coordinates  are  (x  +  $x)  (y  +  $y)  (2  + 8  s) 
from  that  whose  coordinates  are  w yz;  whereas  8 p  is  quite 
a  different  thing,  namely,  the  perpendicular  let  fall  from  the 
point  x  y  z  on  the  wave  surface  passing  through  the  point 
(x  +  tixj  (y  +  $y)  (2  +  82);  which  perpendicular  is  altered  in 
length  when  we  put — hx  for  8,r,  leaving  83/ and  82  unal- 
tered ;  and  this  is  fatal  to  Professor  Kelland's  reasoning. 

8  Park  Terrace,  Cambridge, 
June  7,  1842. 

P.S.  Oct.  7,  1842.— Professor  Kelland  evidently  does  not 
suppose  the  axis  of  y  to  coincide  with  the  direction  of  trans- 
mission: for  suppose  that  it  does,  then  lp  =  8^,  and  there- 
fore equating  the  two  expressions  which  Professor  Kelland 
assumes  to  be  equal  to  w2  at  the  foot  of  page  162,  we  have, 

vF(rK   2  •  ohZy       -  F  (r)  s    9   .  2#8y 
2  — —  8  x*  sin2— ■—  =  Z,  — «  8  w9  sin2  -—■ ; 
r  2  r .  ■  2 

or,  retaining  only  the  first  power  of  k\ 

2^8tf28v2  =  2Z^-8y. 

A*  <J  7* 

Now  it  is  well  known  that  one  of  these  expressions  is  three 
times  the  other.  Hence  Professor  Kelland  does  not  suppose 
the  axis  of  y  to  coincide  with  the  direction  of  transmission. 
The  same  may  be  said  of  the  axes  of  x  and  *. 


[     344     ] 

LXI.  Professor  Kelland's  Vindication  of  himself  against  the 
Charges  of  the  Rev.  M.  O'Brien. 

To  the  Editors  of  the  Philosophical  Magazine  and  Journal. 

Gentlemen,  Paris,  June  5, 1 842. 

f  HAVE  read,  with  extreme  astonishment,  the  attack  made 
on  me  by  Mr.  O'Brien  in  your  Magazine  for  this  month. 
My  first  impression  was  that  it  did  not  become  me  to  reply 
to  it  in  any  shape,  but,  on  refleetion,  it  has  appeared  probable 
that  many  persons  may  read  it  who  are  not  intimately  ac- 
quainted with  the  subject,  on  whom  the  effect  of  silence  would 
be  equivalent  to  the  admission  of  the  justice  of  the  statements 
made.  I  shall  therefore  enter  into  a  brief  explanation,  with 
a  view  to  direct  your  readers  to  the  facts,  not  to  carry  on  a 
controversy.  But  in  commencing  I  am  naturally  induced  to 
ask,  wherein  have  I  offended  Mr.  O'Brien  ?  For  it  must  be 
noted  by  every  one  that  Mr.  O'Brien's  object  is  not  to  "  re- 
ply "  to  my  remarks,  but  to  remove  an  impression  which  he 
thinks  I  have  endeavoured  to  create, M  that  he  has  done  nothing 
in  his  paper  which  had  not  been  already  done  by  myself 
in  my  memoirs."  Now  I  should  be  exceedingly  sorry  to 
create  a  false  impression ;  and  I  am  sure  no  person  who  reads 
my  remarks  will  accuse  me  of  having  done  so  intentionally. 
Still  had  Mr.  O'Brien  candidly  stated  that  such  was  the  im- 
pression on  his  mind,  either  in  your  Journal  or  personally 
when  I  saw  him  in  Cambridge,  I  would  have  addressed  my- 
self diligently  to  remove  it.  But  Mr.  O'Brien's  procedure 
leaves  no  room  for  any  other  course  than  to  reply  publicly  to 
his  charges,  and  leave  it  to  the  world  to  judge  between  us. 

First,  then,  have  I  attributed  to  myself  the  "  notation  "  em- 
ployed, "  the  equations  of  M.  Cauchy,"  the  conclusion  "  that 
transverse  and  normal  vibrations  are  in  general  'propagated 
with  different  velocities  ?  "  Never ;  I  am  not  chargeable  with 
such  dishonesty.  They  are  all,  as  far  as  I  know,  due  to 
Cauchy.  Nor  is  there  one  of  the  conclusions  of  M.  Cauchy 
which  I  have,  even  by  accident,  called  my  own.  I  will  not 
waste  words  about  this.  M.  Cauchy  himself  assures  me  that 
I  have  spoken  with  perfect  justice  and  propriety. 

Secondly,  have  I  attributed  to  myself  the  conclusion  "  that 
homogeneous  light  must  in  general  suffer  dispersion  in  passing 
through  a  prism,  and  dispersion  of  a  discontinuous  nature, 
and  that  this  accounts  for  the  dark  lines  in  the  spectrum  ?  " 
I  never  heard  of  the  conclusion. 

Thirdly,  have  I  endeavoured  to  attribute  to  myself  the  con- 
clusion "  that  the  results  obtained  on  the  hypothesis  of  perfect 


Prof.  Kelland  on  Charges  of  Mr.  O'Brien.  347 

symmetry,  are  also  true  when  the  symmetry  is  disturbed  by 
the  action  of  the  particles  of  matter?"  I  did.  not  know  even 
what  has  to  be  done  on  this  subject.  I  spoke  of  it  thus :  "  It  is 
true  I  did  not  succeed  in  proving  that  the  conditions  resulting 
from  such  an  arrangement  are  the  same  as  those  which  de- 
pend on  the  [supposition  of  perfect  symmetry.  Mr.  O'Brien 
proposes  to  do  this,  and  if  he  succeeds,  it  will,  I  am  sure,  be 
an  important  step  in  our  theoretical  investigations."  All  that 
I  did  and  do  know  on  this  subject  is,  that  M.  Cauchy  has  ar- 
rived at  the  same  conclusion  ;  but,  if  my  memory  serves  me 
right,  under  certain  limitations. 

Lastly,  the  only  portion  of  Mr.  O'Brien's  paper  which  I 
can  be  said  even  remotely  to  have  attributed  to  myself,  is 
that  which  is  contained  in  the  following  sentences  of  Mr. 
O'Brien's  reply.  "  I  have  assumed  that  the  particles  of  aether 
are  acted  upon  by  those  of  matter;  and  I  have  employed  the 
equations  of  M.  Cauchy,  viz. 

r  =  2  m,  &c. 


df 


adapting  them  to  the  case  of  a  set  of  aethereal  particles  acted 
on  by  material." 

"  He  certainly  endeavours,  in  his  *  Theory  of  Heat,'  to  ac- 
count for  dispersion  independently  of  the  hypothesis  of  finite 
intervals"  of  the  particles  of  matter. 

To  the  former  of  these  Mr.  O'Brien  adds  the  observation, 
"  So  far  as  this  I  lay  no  claim  to  originality,  nor  has  Pro- 
fessor Kelland  any  right  to  do  so  either."  Now  as  regards 
the  laying  claim,  to  the  process,  your  readers  will  be  so  kind  as 
to  refer  to  my  paper  and  judge  for  themselves  whether  or  not 
I  have  spoken  modestly ;  and  as  regards  the  right,  I  certainly 
did  believe,  and  do  so  still,  that  it  was  due  to  me.  At  any  rate 
it  was  incumbent  on  him  who  made  the  charge  to  have  fur- 
nished the  proof. 

I  think  I  have  said  enough  to  clear  myself  from  any  im- 
putation of  dishonesty.  I  may  add,  that  my  remarks  were 
written  in  defence  of  a  theory  to  which  I  had  contributed. 
The  express  object  of  my  writing  was  to  prepare  for  further 
discussion  on  the  ■possibility  of  the  hypothesis  of  finite  inter- 
vals. I  was  therefore  constrained  to  show  what  I  believed  to 
be  the  state  of  the  theory,  and  how  Mr.  O'Brien's  hypotheses, 
&c.  differ  from  it.  In  doing  so,  I  never  combated  one  of 
Mr.  O'Brien's  conclusions,  I  never  disparaged  his  hypothesis 
or  his  mode  of  accounting  for  dispersion.  Had  I  erred  in  any 
one  point,  it  was  Mr.  O'Brien's  duty  to  have  set  me  right. 
He  has  not  done  so,  unless  I  am  to  understand  that  certain 

Phil.  Mag.  S.  3.  Vol,  21.  No.  1 39.  Nov.  1 842.    2  A 


346         Prof.  Kelland's  Vindication  of  himself  against 

assertions  about  what  I  have  said  or  denied  suffice  to  effect  it. 
Let  us  take  an  instance  or  two,  and  I  will  add  all  that  can 
be  added  to  such  assertion  by  way  of  answer.  Mr.  O'Brien 
says,  "I  have  arrived  at  a  result  never  obtained  before,  namely, 
that  dispersion  must  arise  from  the  direct  action  of  the  par- 
ticles of  matter  upon  those  of  aether.  This  result  is  denied 
by  Professor  Kelland."  I  answer,  /  never  denied  it.  Of  course 
I  object  to  the  word  must.  The  facts  are  simply  these. 
With  regard  to  the  action  of  the  particles  of  matter  on  those 
of  aether,  M.  Cauchy  and  Mr.  O'Brien  adopt  one  hypothesis, 
whilst  I  had  adopted  another.  On  theirs,  the  velocity  of  trans- 
mission depends  on  the  direct  action  of  the  particles  of  matter ; 
on  mine,  it  does  not.  That  either  or  both  may  be  wrong  is 
perfectly  possible ;  in  groping  after  truth,  we  cannot  reason 
directly  from  data  up  to  laws,  but  must  work  our  way  back 
from  assumed  laws  to  the  experimental  data.  Hence  the  value 
of  researches  such  as  those  before  us.  They  may  ultimately 
lead  to  truth  even  at  the  time  when  least  approaching  to  it. 
I  ought  to  point  out  that  M.  Cauchy  regards  his  equation, 
Nouveaux  Exercices,  vol.  i.  p.  98,  as  embodying  the  explana- 
tion of  dispersion  by  the  direct  action  of  the  particles  of  matter 
on  those  of  aether.  I  am  not  aware,  however,  that  he  has 
ever  stated  so  in  print,  nor  do  I  wish  to  rob  Mr.  O'Brien  of 
the  credit  of  the  explanation. 

But  this  leads  me  to  another  of  Mr.  O'Brien's  assertions. 
"  I  would  ask  Professor  Kelland,  is  it  possible  that  he  thinks 
this  formula  capable  of  accounting  for  dispersion  independ- 
ently of  the  hypothesis  of  finite  intervals  ?  Is  it  not  very  evi- 
dent, except  that  hypothesis  be  true,  that  kAx  is  extremely 
small,  &c.  ?  Why  then  has  Professor  Kelland  produced  this 
expression  as  equivalent  to  mine  ?  "  My  best  answer  to  this 
will  be  to  direct  your  readers  to  turn  back  (which  I  trust  they 
will  not  omit  to  do)  and  see  what  I  have  said.  They  will  find 
the  following  sentence  (and  I  trust  they  will  in  all  cases  read 
the  context) : — "  But  that  effect  depends  on  their  mutual  di- 
stances, and  thusjinite  intervals,  not  indeed  of  the  particles 
of  aether,  but  of  those  of  matter,  necessarily  play  a  conspicuous 
part:"  and  again,  "the  real  difference  between  the  received 
theory  and  that  before  us  is  this ;  that  the  former  rejects  the 
direct  attraction  of  the  particles  of  matter  as  producing  no 
effect  on  the  time  of  vibration  of  a  particle  of  aether,"  &c.&c* 
I  was  perhaps  hardly  justified  in  using  the  word  received,  but 
against  this  there  can  be  no  present  complaint. 

Again,  Mr.  O'Brien  says,  rt  I  have  given  a  simple  proof  of 

*  See  Phil.  Mag.,  S.  3.  No.  132,  (vol.  xx.)  p.  377. 


the  Charges  of  Mr.  O'BTien.  347 

what  was  only  asserted  by  Mr.  Green,  viz.  that  transverse  and 
normal  vibrations  are  in  general  propagated  with  different 
velocities.  I  have  learned  since  that  M.  Cauchy  had  previously 
arrived  at  the  same  result.  Professor  Kelland  distinctly  de- 
nies the  correctness  of  this  result  in  the  Royal  Edinburgh 
Transactions,  vol.  xiv.  p.  396."  I  have  not  the  passage  to 
turn  to,  but  your  readers  have,  and  I  fearlessly  assert,  /  never 
denied  the  correctness  qfM.  Cauchy* s  result.  I  could  not  have 
done  so.  The  assertion,  or  rather  hypothesis,  of  Mr.  Green  is, 
if  my  memory  does  not  deceive  me,  a  very  different  affair. 
But  instead  of  denying  Mr.  Green's  vibration  (which  he  calls 
normal,  but  which  is  really  not  so),  I  have  adopted,  applied, 
and  acknowledged  it  over  and  over  again. 

I  do  not  intend  to  touch  on  every  point  in  Mr.  O'Brien's 
reply.  I  do  not  conceive  that  an  acrimonious  personal  con- 
test can  ever  benefit  the  cause  of  science.  I  shall  therefore 
rest  satisfied  with  clearing  myself.  Had  Mr.  O'Brien  con- 
tented himself  with  saying,  "  I  assert  that  the  equations  at  the 
foot  of  p.  162  of  the  Transactions  of  the  Cambridge  Philoso- 
phical Society  are  essentially  erroneous"  &c,  "  they  prove 
that  Mr.  Kelland's  equations  in  the  Cambridge  Philosophical 
Transactions,  vol.  vi.  p.  159,  are  essentially  erroneous"  I  would 
have  excused  the  harshness  of  the  term  "  essentially  erroneous" 
in  italics,  and  have  given  the  following  explanation.  It  is 
perfectly  possible  that  these  two  equations  may  be  written 
down  unaccompanied  by  the  restriction  that  one  of  the  axes 
of  coordinates  is  the  direction  of  transmission ;  nay  more,  it  is 
perfectly  possible  that  I  have  stated  that  g  is  not  necessarily 
measured  along  an  axis.  The  fact  is  this :  all  these  equations 
were  deduced  on  the  hypothesis  that  the  axis  of  y  is  the  axis  of 
transmission. 

When  the  paper  was  copied  for  the  press  (by  my  friend 
Mr.  Bird)  certain  interpolations  were  introduced,  which,  as 
1  never  saw  the  proof  sheets,  remain  on  the  pages.  This  ex- 
planation must  not  be  understood  as  the  admission  of  my 
having  fallen  into  error  further  than  it  states. 

I  assert,  first,  that  when  it  is  remembered  that  one  of  the 
axes  is  that  of  transmission,  all  my  equations  in  that  memoir 
are  correct ;  and  secondly,  that  I  never  deduced  one  result 
from  an  equation  which  is  not  correct,  so  far  as  that  memoir 
is  concerned. 

Mr.  O'Brien's  argument  that  because  M.Cauchy's  equation 
is  of  one  form  and  mine  of  another,  one  must  be  incorrect,  is 
only  good  when  the  hypotheses  are  identical.  That  they  are 
not  stated  to  be  otherwise  must  be  a  fault  of  mine.  But  I 
have  never  employed  the  equations  in  this  form,  to  the  best  of 

2  A2 


34-8        Dr.  Draper  on  certain  Spectral  Appearances 

my  knowledge,  so  that  the  erroneousness  of  an  equation  af- 
fects nothing  but  the  equation  itself. 

Mr.  O'Brien's  argument  against  the  equations  I  have  used, 
viz.  that 


CFr  .  2kdg\ 


is  not  zero,  is  good  only  on  the  hypothesis  that  g  is  not 
measured  along  one  of  the  axes.  Had  Mr.  O'Brien  read 
my  papers  he  would  have  seen  that  I  have  twenty  times  over 
at  least,  given  this  expression  a  value  which  is  not  zero.  But 
when  the  direction  of  transmission  in  an  isotrope  medium  is 
under  one  of  the  axes,  the  expression  is  zero.  And  these  are 
the  only  circumstances  in  which  I  have  used  it  as  such ;  your 
readers  will  find  my  fundamental  equations  deduced  in  your 
Magazine  for  May,  1837.  I  think  they  will  see  my  views  cor- 
rectly stated  there,  and  trust  they  will  do  me  the  justice  to 
examine  them  before  they  give  credence  to  the  following  as- 
sertions of  Mr.  O'Brien  : — 

"  And  here  I  must  enter  a  decided  protest  against  all  Pro- 
fessor Kelland's  reasoning  on  the  subject  of  transverse  and 
normal  vibrations."  "  Now  this  error  in  the  fundamental 
equations  vitiates  all  his  results,  so  far  as  they  relate  to  the  na- 
ture of  the  vibrations  and  the  velocity  of  propagation,"  &c. 
"  This  error  runs  through  all  Professor  Kelland's  papers  and 
his  f  Theory  of  Heat,'  so  far  as  I  have  read  them,"  &c. 

What  could  have  dictated  such  expressions  so  utterly  un- 
grounded, I  leave  to  the  world  to  judge. 

In  conclusion,  Gentlemen,  allow  me  to  thank  you  for  your 
kindness  in  receiving  my  former  communications,  and  to  re- 
quest that  you  will  publish  this  in  your  forthcoming  Number. 
I  have  the  honour  to  be  your  obliged  Servant, 

P.  Kelland. 

LXII.  On  certain  Spectral  Appearances,  and  on  the  discovery 
of  Latent  Light.  By  J.  W.  Draper,  M.D.,  Professor  of 
Chemistry  in  the  University  of  New  York. 

To  the  Editors  of  the  Philosophical  Magazine  and  Journal. 
Gentlemen, 
TF  there  be  a  thing  in  which  I  have  a  disinclination  to  en- 
gage,  it  is  controversy  of  a  personal  kind  with  scientific 
fellow-labourers.  But,  as  you  well  know,  it  ordinarily  happens 
that  there  is  no  other  gain  to  philosophers  beyond  the  mere 
credit  of  their  discoveries,  they  may  be  forgiven  for  reluc- 
tantly endeavouring  to  secure  this  their  only  reward. 

I  have  recently  returned  from  a  long  journey,  undertaken 


FhiLMag.  S.3.  VoLJZL  £11. 


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\ffltrmt/'i/imti.";i!!ir;:«uiiaari<lZL 


wmiiMii/mmiimmiiim/miitti 


Linear  Solar  Spectra  with  their  corresponding  Tithonographs 
shewing  thcPhysical  independence  of  Tithoniat\  and  Light. 


and  on  the  Discovery  of  Latent  Light.  349 

for  the  purpose  of  making  trials  on  the  sunlight  in  lower  lati- 
tudes, and  am  grieved  to  see  in  the  reports  that  have  reached 
this  country  of  the  Proceedings  of  the  British  Association, 
certain  announcements,  received  from  Professor  Bessel*,  of 
phantoms  which  can  be  produced  on  surfaces  by  mercury  va- 
pour, by  the  breath,  and  other  means, — as  though  the  thing  were 
new.  Years  ago,  if  you  look  in  your  own  Journal  (February 
1840,  p.  84);  Sept.  1840,  p.  218;  Sept.  1841,  pp.  198,  199; 
you  will  find  that  1  had  published  facts  of  the  kind ;  spectral 
appearances,  that  could  be  revived  on  metals,  glass,  and  other 
bodies,  by  the  breath,  by  vapour  of  camphor,  by  mercury 
vapour,  &c.  The  very  purpose  for  which  I  described  them  was 
the  striking  resemblance  of  some  of  them  to  Daguerreotype 
images.  I  have  repeatedly  shown,  that  by  placing  a  coin  or 
any  other  object  on  iodized  .silver,  in  the  dark,  the  vapour  of 
mercury  will  bring  out  a  representation  of  it.  And  in  one  of 
the  papers  just  quoted,  the  condition  under  which  camera 
images  can  be  reproduced  on  a  silver  plate,  even  after  the 
plate  has  been  rubbed  with  rottenstone,  is  described. 

I  have  further  seen  (Literary  Gazette,  July  23,  1842,  Paris 
letter)  that  the  fact  that  light  becomes  latent  in  bodies,  after 
the  manner  of  heat,  was  announced  in  France  as  a  new  and 
important  discovery  of  Professor  Moser  of  Kbnigsburg.  In 
your  own  Journal,  more  than  a  year  ago,  you  printed  a  long 
paper  written  by  me  on  this  very  t  opic  (September  1841, 
pp.  196,  204,  205,  206),  not  merely  announcing  the  fact,  but 
giving  rude  estimates  of  the  amounts :  more  exact  numerical 
determinations  I  have  now  nearly  ready  for  the  press. 

But  I  will  trouble  you  no  further  with  these  private  matters, 
simply  hoping  that  your  numerous  readers,  who  feel  an  in- 
terest in  such  things,  will  turn  for  themselves  to  the  pages  I 
have  quoted. 

The  accompanying  photographic  impression  of  the  solar 
spectrum,  which  I  will  thank  you  to  give  to  Sir  John  Her- 
schel,  was  obtained  in  the  south  of  Virginia : — probably  you 
can  make  nothing  like  it  in  England,  the  sunlight  here  in 
New  York  wholly  fails  to  give  any  such  result.  It  proves, 
that  under  a  brilliant  sun,  there  is  a  class  of  rays  commencing 
precisely  at  the  termination  of  the  blue,  and  extending  beyond 
the  extreme  red,  which  totally  and  perfectly  arrest  the  action 
of  the  light  of  the  sky.  This  impression  was  obtained  when 
the  thermometer  was  96°  Fahr.  in  the  shade,  and  the  nega- 
tive rays  seem  almost  as  effective  in  protecting,  as  the  blue 
rays  are  in  decomposing  iodide  of  silver. 

*  We  give  among  the  miscellaneous  articles  of  the  present  Number, 
page  409,  a  report  from  the  Athenaeum  of  what  passed  at  the  meeting  at 
Manchester  upon  this  subject. — Ed. 


350        Dr.  Draper  on  certain  Photographic  Impressions. 

The  most  remarkable  part  of  the  phenomenon  is,  that  the 
same  class  of  rays  makes  its  appearance  again  beyond  the  ex- 
treme lavender  ray.  Sir  J.  Herschel  has  already  stated,  in 
the  case  of  bromide  of  silver,  that  these  negative  rays  exist 
low  down  in  the  spectrum.  This  specimen,  however,  proves 
that  they  exist  at  both  ends,  and  do  not  at  all  depend  on  the 
refrangibility.  It  was  obtained  with  yellow  iodide  of  silver, 
Daguerre's  preparation,  the  time  of  exposure  to  the  sun  fif- 
teen minutes. 

In  this  impression,  six  different  kinds  of  action  may  be  di- 
stinctly traced  by  the  different  effects  produced  on  the  mer- 
curial amalgam.  These,  commencing  with  the  most  refran- 
gible rays,  may  be  enumerated  as  follows: — 1st,  protecting 
rays ;  2nd,  rays  that  whiten ;  3rd,  rays  that  blacken ;  4th, 
rays  that  whiten  intensely;  5th,  rays  that  whiten  very  feebly; 
6th,  protecting  rays. 

It  is  obvious  we  could  obtain  negative  photographs  by  the 
Daguerreotype  process  by  absorbing  all  the  rays  coming  from 
natural  objects,  except  the  red,  orange,  yellow,  and  green, 
allowing  at  the  same  time  diffused  daylight  to  act  on  the 
plate. 

This  constitutes  a  great  improvement  in  the  art  of  photo- 
graphy, because  it  permits  its  application  in  a  negative  way  to 
landscapes.  In  the  original  French  plan  the  most  luminous 
rays  are  those  that  have  least  effect,  whilst  the  sombre  blue 
and  violet  rays  produce  all  the  action.  Pictures,  produced 
in  that  way,  never  can  imitate  the  order  of  light  and  shadow 
in  a  coloured  landscape. 

If  it  should  prove  that  the  sunlight  in  tropical  regions  dif- 
fers intrinsically  from  ours,  it  would  be  a  very  interesting 
physical  fact.  There  are  strong  reasons  to  believe  it  is  so. 
The  Chevalier  Fredrichstal,  who  travelled  in  Central  America 
for  the  Prussian  government,  found  very  long  exposures  in  the 
camera  needful  to  procure  impressions  of  the  ruined  monu- 
ments of  the  deserted  cities  existing  there.  This  was  not  due 
to  any  defect  in  his  lens ;  it  was  a  French  achromatic,  and 
I  tried  it  in  this  city  with  him  before  his  departure.  The 
proofs  which  he  obtained,  and  which  he  did  me  the  favour  to 
show  me  on  his  return,  had  a  very  remarkable  aspect.  More 
recently,  in  the  same  country,  other  competent  travellers  have 
experienced  like  difficulties,  and  as  I  am  informed  failed  to 
get  any  impressions  whatever.  Are  these  difficulties  due  to 
the  antagonizing  action  of  the  negative  rays  upon  the  po- 
sitive ? 

Yours  truly, 

Uuiversity,  New  York,  J.  W.  DRAPER. 

Sept.  26,  1842. 


A 


[351  ] 

LXIII.  Note  regarding  the  Structure  of  Muscle, 
By  Martin  Barry,  M.D.,  F.R.SS.  L.  and  E.* 
TN  Part  I.  of  the  Philosophical  Transactions  for  the  present 
~  year  (p.  99)  I  mentioned  having  often  seen  a  muscular 
fibril  becoming  a  fasciculus ;  and  gave  delineations  of  fibrils 
undergoing  this  change.  I  happen  to  have  just  made  a  pre- 
paration in  which  the  transition  is  remarkably  well  seen,  and 
have  sketched  it  (chiefly  in  outline)  in  the  accompanying  figure. 
At  A,  the  young  fasciculus  still  exhibits  the  double  spiral ; 
while  at  B,  it  is  so  far  advanced  as  to  present  the  usual  trans- 
verse striae.  Here  the  striae  are  too  minute  for  examination. 
The  preparation  is  from  muscle  of  a  fish.  In  the  fasciculus 
C    (from   the   Turtle),    the 

transverse  striae  are  obviously  /*"?» 

produced  by  the  windings  of 
spiral  threads.  D  represents 
an  enlarged  fibril  or  young 
fasciculus,  varying  in  its  ap- 
pearance at  different  parts 
from  being  twisted  on  itself. 
The  preparations  themselves 
are  in  a  state  in  which  they 
may  be  viewed  by  my  friends. 

It  is  a  striking  fact,  that 
the  conversion  of  the  fibril 
into  the  fasciculus  is  more 
frequently  met  with  in  the 
ever-acting  heart,  than  in  any 
other  part  that  I  have  exami- 
ned. The  heart  of  the  Turtle 

is  that  which  I  usually  em-  r""  \ 

ploy  and  recommend.     The 

muscle  may  be  preserved  in  very  dilute  spirit,  a  drop  of  which 
is  preferable  to  water  as  a  medium  for  the  examination.  It 
will  be  found  advantageous  to  freeze  the  muscle,  as  then  it  is 
possible,  by  means  of  a  razor,  drawn  in  the  direction  of  the 
fibres,  to  slice  off  an  exceedingly  thin  lamina,  which  being 
thawed,  a  narrow  strip  of  it  should  be  detached  and  teased  out 
with  needles.  , 

Fibrils  are  reproduced  and.  multiplied  by  means  of  nuclei, 
which  in  certain  states  present  the  appearance  of  rows  of  bead- 
like particles.  These, — the  mere  elements  of  spirals, — seem 
to  be  what  some  observers  have  supposed  to  represent  the 
structure  of  the  formed  fibril. 

*  Communicated  by  the  Author. 


k 


IB 


[  352  ] 

LXIV.    On  the  Preparation  of  Artificial  Yeast.    By  George 
Fownes,  Ph.D.* 

TT  often  becomes  a  matter  of  great  practical  importance  to 
-*■  have  it  in  our  power  to  excite  the  vinous  fermentation  under 
circumstances  in  which  ordinary  yeast  cannot  be  obtained.  In 
making  bread,  for  example,  although  the  use  of  yeast  may  be 
avoided  by  employing  what  is  called  "leaven,"  or  dough 
which  has  already  become  sour  and  partly  putrefied  by  spon- 
taneous change — a  practice  which  has  been  followed  from  the 
most  remote  antiquity,  and  is  still  occasionally  in  use — the 
bread  so  made  is  always  to  be  distinguished  by  a  peculiar  sour 
and  nauseous  taste  and  smell,  and  can  never  bear  comparison 
with  that  fermented  by  yeast. 

The  object  of  the  present  notice  is  to  point  out  a  method 
by  which  yeast  of  the  most  unexceptionable  quality  can  be 
artificially  produced  at  will.  I  am  aware  that  some  substitute 
for  ordinary  ferment  in  brewing  has  long  been  known  to  cer- 
tain persons,  who  go  about  the  country  and  impart  their  secret 
to  those  who  are  willing  to  purchase  it :  of  the  nature  of  this 
preparation  I  am  ignorant,  and  a  reference  to  systematic  che- 
mical works  will  suffice  to  show,  that  whatever  it  be  it  has 
never  been  made  public. 

On  turning  to  Berzelius,  it  will  be  found  stated f,  that 
although  the  reproduction,  as  it  were,  of  yeast,  the  conversion 
of  a  small  into  a  large  quantity,  is  a  very  easy  thing,  yet  to 
produce  that  substance  from  the  beginning  is  very  difficult. 
He  describes  a  process  for  this  purpose  on  the  authority  of 
Dr.  Henry,  and  which  consists  in  taking  a  strong  infusion  of 
malt,  saturating  it  with  carbonic  acid,  and  then  exposing  it 
for  some  days  to  the  proper  fermenting  temperature,  when  a 
small  quantity  of  yeast  is  gradually  formed  and  deposited, 
which  may,  by  various  contrivances,  be  made  to  give  origin 
to  a  larger.  I  shall  have  occasion  to  notice  presently  the  be- 
haviour of  a  malt  infusion  when  left  to  itself  at  a  temp,  of  70°  or 
80°  F.  for  some  time,  and  to  show  that  the  addition  of  carbonic 
acid  is  wholly  unnecessary. 

The  principle  of  induced  chemical  action,  which  Liebig  has 
assumed  to  explain  a  great  number  of  those  extraordinary 
phaenomena  to  which  Berzelius  gave  the  term  "  Catalysis  J," 
and  which  principle  has  been  so  fully  confirmed,  and  even, 
perhaps,  extended  by  the  late  valuable  researches  of  MM. 

*  Communicated  by  the  Chemical  Society,  having  been  read  March  15, 
1842. 

•f*  Lehrbuch,  vol.  viii.89.  foot  note,  third  edition. 
[J  See  Phil.  Mag.,  S.  3.  vol.  x.  p.  490.—Edit.] 


Mr.  Fownes  on  the  Preparation  of  Artificial  Yeast.     353 

Boutron  and  Fremy  on  the  formation  of  lactic  acid,  serves  to 
solve  this  difficulty,  as  it  will  doubtless  many  others  of  far 
greater  magnitude  and  importance.  It  has  been  shown  that 
"  the  kind  of  chemical  change  going  on  in  the  decomposing  azo- 
tized  body  or  ferment,  determines  the  kind  of  decomposition 
which  shall  occur  in  the  neutral  ternary  substance,  subject  to 
its  influence;"  that  diastase,  for  example,  according  to  its 
peculiar  condition,  whether  fresh  from  the  germinated  grain, 
slightly  putrefied,  or  in  a  still  more  advanced  state  of  that 
change,  possesses  the  singular  power,  in  the  first  case,  of 
changing  starch  into  dextrin,  and  ultimately  into  grape  sugar; 
in  the  second,  of  causing  the  conversion  of  sugar  into  lactic 
acid ;  and  in  the  third  and  last,  of  exciting  the  vinous  fermen- 
tation. 

Now  if  common  wheaten  flour  be  mixed  with  water  to  a 
thick  paste,  and  exposed,  slightly  covered,  to  spontaneous 
change  in  a  moderately  warm  place,  it  will  be  observed  to 
run  through  a  series  of  changes  which  seem  very  closely  to 
resemble  those  described  by  MM.  Boutron  and  Fremy  in  the 
case  of  diastase. 

About  the  third  day  of  such  exposure  it  begins  to  emit  a 
little  gas,  and  to  exhale  an  exceedingly  disagreeable  sour  odour, 
much  like  that  of  stale  milk ;  after  the  lapse  of  some  time  this 
smell  disappears,  or  changes  in  character,  the  gas  evolved  is 
greatly  increased,  and  is  accompanied  by  a  very  distinct  and 
somewhat  agreeable  vinous  odour :  this  will  happen  about  the 
sixth  or  seventh  day,  and  the  substance  is  then  in  a  state  to 
excite  the  alcoholic  fermentation. 

A  quantity  of  brewers'  wort  is  next  to  be  prepared  in  the 
usual  manner,  by  boiling  with  hops ;  and  when  cooled  to  90° 
or  100°,  the  decomposed  dough  before  described,  after  being 
thoroughly  mixed  with  a  little  tepid  water,  is  added  to  it,  and 
the  temperature  kept  up  by  placing  the  vessel  in  a  warm  si- 
tuation. After  the  lapse  of  a  few  hours  active  fermentation 
commences;  abundance  of  carbonic  acid,  having  its  usual 
agreeable  pungent  smell,  is  disengaged,  and  when  the  action 
is  complete  and  the  liquid  clear,  a  large  quantity  of  excellent 
yeast  is  found  at  the  bottom,  well  adapted  to  all  purposes  to 
which  that  substance  is  applied. 

In  one  experiment  the  following  materials  were  used : — a 
small  handful  of  ordinary  wheat  flour  was  made  into  thick 
paste  with  cold  water,  covered  with  paper,  and  left  seven  days 
on  the  mantel-shelf  of  a  room  where  a  fire  was  kept  all  day, 
being  occasionally  stirred:  at  the  end  of  that  period  three  quarts 
of  malt  were  mashed  with  about  two  gallons  of  water,  the  infu- 
sion boiled  with  the  proper  quantity  of  hops,  and  when  suffi- 


854     Mr.  Fownes  on  the  Preparation  of  Artificial  Yeast. 

ciently  cooled,  the  ferment  added.  The  results  of  the  experi- 
ment were,  a  quantity  of  beer,  not  very  strong,  it  is  true,  but 
quite  free  from  any  unpleasant  taste,  and  at  least  a  pint  of 
thick  barm,  which  proved  perfectly  good  for  making  bread. 

It  appears  to  me  that  this  simple  plan  would  enable  distant 
residents  in  the  country,  and  settlers  in  the  colonies,  to  enjoy 
the  luxury  of  good  bread  when  a  little  malt  could  be  got — 
a  very  easy  home  manufacture  from  grain  of  any  kind :  the 
hops  might  probably  be  omitted  when  the  yeast  alone  was  the 
object. 

A  moderately  strong  infusion  of  malt  which  has  not  been 
boiled,  suffered  to  stand  in  a  warm  place  for  some  days, 
speedily  becomes  sour  and  turbid,  and  begins  to  evolve  gas ; 
this  change  rapidly  progresses,  carbonic  acid  is  given  out 
plentifully,  and  a  deposit  of  thick  insoluble  whitish  matter 
formed,  which  readily  excites  fermentation  in  a  dilute  solution 
of  sugar;  the  supernatant  liquid  contains  alcohol,  acetic  acid, 
and,  I  believe,  lactic  acid. 

When  wort  which  has  been  boiled  and  hopped  is  set  aside 
to  decompose  spontaneously,  the  change  it  undergoes  appears 
to  depend  very  much  upon  its  strength.  When  weak,  three 
or  four  days  elapse  before  anything  is  noticed ;  a  scum  then 
collects  upon  the  surface,  and  a  brown  flocculent  substance  is 
thrown  down,  which  is  incapable  of  exciting  fermentation  in  a 
solution  of  sugar,  while  the  liquid  gives  off  a  flat,  offensive 
smell.  If  the  infusion  experimented  on  be  stronger,  then  the 
change  is  different :  the  liquid  becomes  turbid  from  the  sepa- 
ration of  a  yellowish  adhesive  substance,  a  good  deal  of  gas  is 
very  slowly  emitted,  alcohol  is  formed,  and  the  deposit  at  the 
bottom  of  the  vessel  proves  a  pretty  active  ferment  to  sugar. 
The  acidity  of  the  liquid  is  but  trifling,  and  its  smell  is  some- 
what disagreeable.  These  differences  in  the  behaviour  of 
boiled  wort  may  also  depend  upon  the  quantity  of  hops  added 
and  the  length  of  time  during  which  the  ebullition  had  been 
continued. 

The  effect  produced  in  a  spontaneously  fermentable  liquid  by 
vegetable  acids,  or  acid  salts,  such  as  cream  of  tartar,  is  a  cu- 
rious subject  of  inquiry.  From  an  experiment  made  upon  some 
wort,  it  appeared  not  improbable  that  the  result  of  such  addi- 
tion showed  an  interference  in  the  formation  of  lactic  acid. 
We  know  that  when  the  juice  of  grapes,  or  currants  and  goose- 
berries, is  exposed  to  the  air,  the  vinous  fermentation  is  set  up 
apparently  at  once ;  whereas  in  an  unboiled  infusion  of  malt, 
which  is  destitute  of  these  substances,  lactic  acid  seems  to  be 
first  formed,  although  ultimately  the  two  fermentations  go  on 
together. 


Mr.  Croft  on  some  Salts  of  Cadmium.  355 

I  stated,  when  speaking  of  the  spontaneous  decomposition 
of  wheaten  dough,  that  an  acid  state  preceded  that  in  which 
it  became  an  alcoholic  ferment ;  and  if  in  this  condition  it  be 
mixed  with  a  dilute  solution  of  common  sugar,  and  the  whole 
kept  warm  for  several  days,  it  furnishes  a  sour  liquid  which  is 
rich  in  lactic  acid,  and  from  which  white  crystallized  lactate 
of  zinc  is  easily  prepared.  There  is  a  tendency  in  the  liquid 
to  run  into  the  alcoholic  fermentation,  and  to  produce  vinegar 
by  a  subsequent  change,  but  still  the  quantity  of  lactic  acid  so 
formed  is  very  considerable. 

Common  wheat-gluten  then  in  its  mode  of  decomposition 
strikingly  resembles  diastase ;  like  that  substance  it  runs  in 
succession  through  two  different  dynamic  conditions ;  it  is 
successively  a  lactic  acid  and  an  alcohol  ferment;  is  it  too 
much  to  expect  that  it  might  by  proper  means  be  detected  in 
a  third  condition,  namely,  as  a  "  sugar  ferment,"  like  diastase 
itself  in  the  state  in  which  it  exists  in  malt  ?  Is  it  not  possible 
that  diastase,  as  a  definite  proximate  principle,  has  no  more 
existence  than  yeast ;  that  its  powers  are  purely  dynamic,  and 
that  it  is,  in  short,  nothing  more  than  the  gluten  of  the  seed 
in  one  of  its  earliest  stages  of  decomposition?  This  is  an  in- 
teresting inquiry,  but  its  prosecution  will  be  somewhat  difficult 
from  the  rapidity  with  which  these  changes  succeed  each  other ; 
it  must  be  remembered  that  no  one  has  yet  succeeded  in  get- 
ting diastase  in  a  state  fit  for  analysis. 


LXV.    On  some  Salts  of  Cadmium.    By  Henry  Croft,  Esq.* 

/"^  HLORIDE  of  cadmium  is  exceedingly  soluble  in  water  and 
^-/  cannot  be  obtained  in  good  crystals.  If  it  be  treated  with 
a  solution  of  ammonia,  it  is  not  at  first  dissolved ;  but  on  heat- 
ing, the  white  powder  which  is  at  first  formed,  disappears, 
and  on  cooling  a  granular  crystalline  powder  falls  out  of  the 
solution.  It  is  a  compound  of  the  chloride  with  ammonia.  By 
heating,  it  loses  16'63  per  cent  of  ammonia ;  according  to  the 
formula  CdCl  +  H3N  it  would  lose  15*12;  the  excess  ob- 
tained is  owing  to  a  portion  of  the  chloride  being  decomposed 
when  sal-ammonia  is  evolved.  The  proof  of  this  is  that  the 
heated  salt  is  not  perfectly  soluble  in  water. 

If  dry  ammonia  be  passed  over  pulverised  anhydrous  chlo- 
ride of  cadmium,  the  powder  increases  greatly  in  bulk  under 
evolution  of  heat.  At  first  there  is  but  little  action,  and  the 
stream  of  ammonia  must  be  passed  over  the  salt  for  some  time 
before  violent  absorption  takes  place.      1*276  gr.  absorbed 

*  Communicated  by  the  Chemical  Society,  having  been  read  May  1 7, 1842. 


356  Mr.  Croft  on  some  Salts  of  Cadmium. 

0*6835.gr.  of  ammonia,  or  100  parts  absorbed  53*56;  accord- 
ing to  the  formula  Cd  CI  +  3  N  H3  it  would  be  56*47 :  the 
difference  probably  arises  from  the  great  increase  in  bulk 
which  the  salt  undergoes,  and  which  may  prevent  the  ammo- 
nia reaching  every  particle. 

This  compound  loses  ammonia  when  exposed  to  the  air ; 
when  it  has  ceased  to  smell  of  ammonia,  it  is  converted  into 
the  first-mentioned  compound,  viz.  that  containing  one  atom 
of  ammonia. 

Bromide  of  cadmium  crystallizes  in  long  prisms  somewhat 
similar  to  nitre ;  it  loses  its  water  of  crystallization  when  ex- 
posed to  a  dry  atmosphere :  2*422  grs.  lost,  when  heated  to 
100°,  0*5075  gr.  of  water;  that  is,  20*95  per  cent;  accord- 
ing to  the  formula  Cd  Br  +  4  aq  it  should  be  21*17 :  it  fuses 
easily  and  crystallizes  on  cooling.  Bromide  of  cadmium  dis- 
solves in  hot  caustic  ammonia,  and  gives  on  cooling  a  granu- 
lar crystalline  powder;  by  slow  cooling  the  salt  is  deposited 
in  the  form  of  regular  octohedrons.  It  contains  11*69  per 
cent,  of  ammonia,  or  1  atom,  and  is  therefore  analogous  to 
the  chloride/ 

The  anhydrous  bromide  absorbs  a  large  quantity  of  ammo- 
nia, like  the  chloride,  but  the  quantity  varies  between  two  and 
three  atoms*. 

All  these  compounds  are  decomposed  by  water,  and  oxide 
of  cadmium  is  separated. 

The  chloride,  bromide  and  iodide  of  cadmium  form  very 
beautiful  double  salts  with  the  alkaline  chlorides,  bromides 
and  iodides. 

They  may  be  prepared  by  dissolving  the  respective  salts  in 
atomic  proportions. 

Cadmio-chloride  of  potassium. — From  the  concentrated  so- 
lution the  salts  crystallize  in  silky  needles  which  contain 
water.  If  these  crystals  be  allowed  to  stand  in  the  solution 
they  gradually  disappear,  and  large  crystals  are  formed  in  their 
stead  ;  they  have  the  form  of  regular  rhombohedrons ;  they 
contain  no  water.  Their  formula  is  Cd  CI  +  KC1;  the  aci- 
cular  salt  contains  one  atom  of  water.  100  parts  of  water  at 
60°  F.  dissolve  33*45. 

Cadmio-bromide  of  potassium  is  precisely  similar  to  the 
double  chloride :  it  is,  however,  much  more  soluble  in  water. 
Formula  Cd  Br  +  KBr.     The  acicular  salt  contains  water. 

Cadmio-iodide,  &c,  does  not  crystallize  like  the  bromide 

*  In  the  last  number  of  the  Reports  of  the  Academy  of  Berlin,  I  find 
that  Raramelsberg  has  prepared  and  analysed  the  crystallized  bromide  and 
its  compounds  with  ammonia.  That  prepared  in  the  dry  way  contains,  as 
he  says,  two  atoms  of  ammonia. 


Mr.  Murchison  on  the  Salt  Steppe  south  of  Orenburg.     357 

and  chloride ;  the  anhydrous  salt  is  Cd  I  +  KI.  It  is  very 
soluble  in  water. 

Cadmio-chloride  of  sodium  does  not  crystallize  in  a  regular 
form,  but  in  verrucose  crystals.  The  formula  is  Cd  CI  + 
Na  CI  +  3  aq.     100  parts  of  water  at  60  dissolve — 71*32. 

Cadmio-chloride  of  ammonium  crystallizes  like  the  potassium 
salt  in  two  forms ;  the  large  crystals  are  anhydrous. 

All  these  salts  are  somewhat  soluble  in  alcohol  and  wood- 
spirit,  but  not  so  much  so  as  the  simple  chloride,  iodide  and 
bromide. 

The  analyses  of  these,  as  well  as  some  other  salts  of  cad- 
mium, will  be  published  in  a  second  paper. 

LXVI.  On  the  Salt  Steppe  south  of  Orenburg,  and  on  a  re- 
markable Freezing  Cavern.  By  Roderick  Impey  Mur- 
chison, Esq.,  Pres.  G.S.* 

HPHIS  salt  steppe  is  distinguished  from  many  of  those  which  are 
■*■  interposed  between  the  Ouralsk  and  the  Volga  or  are  situated 
on  the  Siberian  side  of  the  Ural  Mountains,  by  consisting  not  of 
an  uniform  flat  resembling  the  bed  of  a  dried-up  sea,  but  of  wide 
undulations  and  distantly  separated  low  ridges  ;  nevertheless  it  is, 
Mr.  Murchison  states,  a  true  steppe,  being  devoid  of  trees  and  little 
irrigated  by  streams.  The  surface  consists  of  gypseous  marls  and 
sands,  considered  by  the  author  to  be  of  the  age  of  the  zechsteinf, 
and  it  is  pierced  in  the  neighbourhood  of  the  imperial  establishment 
of  Uletzkaya  Zatchita  by  small  pyramids  of  rock-salt.  These  pro- 
truding masses  attracted  the  attention  of  the  Kirghiss  long  before 
the  country  was  colonized  by  the  Russians,  but  it  is  only  during  a 
short  period  that  the  great  subjacent  bed  has  been  extensively 
worked.  The  principal  quarries,  exposed  to  open  day,  are  situated 
immediately  south  of  the  establishment,  and  have  a  length  of  300 
paces,  with  a  breadth  of  200  and  a  depth  of  40  feet.  The  mass  of 
salt  thus  exposed,  is  of  great  purity,  the  only  extraneous  ingredient 
being  gypsum,  distantly  distributed  in  minute  filaments.  At  first 
sight  the  salt  seems  to  be  horizontally  stratified,  but  this  apparent 
structure,  Mr.  Murchison  states,  is  owing  to  the  mineral  being  ex- 
tracted in  large  parallelopipedal  blocks  twelve  feet  long,  three  feet 
deep  and  three  wide.  On  the  side  where  the  quarry  was  first 
worked,  the  cuttings  presented,  in  consequence  of  the  action  of  the 
weather,  a  vertical  face  as  smooth  as  glass,  but  at  its  base  there 
was  a  black  cavern  formed  by  the  water  which  accumulates  at  cer- 
tain periods  of  the  year,  and  froni  its  roof  were  saline  stalactites. 

*  From  the  Proceedings  of  the  Geological  Society,  vol.  ii.  part  2;  ha- 
ving been  read  March  9, 1842. 

j-  His  extensive  surveys  of  Russia  have  convinced  Mr.  Murchison  that 
rock-salt  and  salt  springs  occur  in  all  the  lower  sedimentary  rocks  of  that 
empire,  from  great  depths  below  the  Devonian  or  old  red  sandstone  system 
to  the  zechstein  and  the  overlying  marls  and  sandstones. 


358  Mr.  Murchison  on  the  Freezing  Cave  of  llletzkaya  Zatchita. 

The  entire  range  of  this  bed  of  salt  is  not  known,  but  the  mass  has 
been  ascertained  to  extend  two  versts  in  one  direction,  and  Mr. 
Murchison  is  of  opinion  that  it  constitutes  the  subsoil  of  a  very  large 
area ;  its  entire  thickness  also  does  not  appear  to  have  been  deter- 
mined, but  it  is  stated  to  exceed  100  feet.  The  upper  surface  of 
the  deposit  is  very  irregular,  penetrating,  in  some  places,  as  already 
mentioned,  the  overlying  sands  and  marls. 

In  consequence  of  the  salt  occurring  at  so  small  a  depth  every 
pool  supplied  with  springs  from  below  is  affected  by  it*  ;  and  one 
of  them  used  by  the  inhabitants  as  a  bath  is  so  highly  charged  with 
saline  contents  that  there  is  a  difficulty  in  keeping  the  body  sub- 
merged, and  the  skin  on  leaving  the  pool  is  encrusted  with  salt. 
This  brine  swarms  with  animalcules. 

Mr.  Murchison  then  describes  the  freezing  cavern  and  the 
phasnomena  exhibited  by  it.  The  cave  is  situated  at  the  southern 
base  of  a  hillock  of  gypsum  at  the  eastern  end  of  the  village  con- 
nected with  the  imperial  establishment ;  and  it  is  one  of  a  series  of 
apparently,  for  the  greater  part,  natural  hollows,  used  by  the  pea- 
santry for  cellars  or  stores.  The  cave  in  question  is,  however,  the 
only  one  which  possesses  the  singular  property  of  being  partially 
filled  with  ice  in  summer  and  of  being  destitute  of  it  in  winter. 
"  Standing  on  the  heated  ground  and  under  a  broiling  sun,  I  shall 
never  forget,"  says  the  author,  "  my  astonishment  when  the  woman 
to  whom  the  cavern  belonged  unlocked  a  frail  door  and  a  volume 
of  air  so  piercingly  keen  struck  the  legs  and  feet  that  we  were  glad 
to  rush  into  a  cold  bath  in  front  of  us  to  equalize  the  effect."  Three 
or  four  feet  within  the  door  and  on  a  level  with  the  village  street, 
beer  and  quash  were  half  frozen.  A  little  further  the  narrow  chasm 
opened  into  a  vault  fifteen  feet  high,  ten  paces  long,  and  from  seven 
to  eight  wide,  which  seemed  to  send  off  irregular  fissures  into  the  body 
of  the  hillock.  The  whole  of  the  roof  and  sides  were  hung  with  solid 
undripping  icicles,  and  the  floor  was  covered  with  hard  snow,  ice, 
or  frozen  earth.  During  the  winter  all  these  phenomena  disappear, 
and  when  the  external  air  is  very  cold  and  all  the  country  is  frozen 
up,  the  temperature  of  the  cave  is  such  that  the  Russians  state  thev 
could  sleep  in  it  without  their  sheep-skins. 

In  order  to  lay  before  the  Society  an  explanation  of  these  curious 
opposite  conditions  of  the  cave,  the  author  communicated  with  Sir 
JohnHerschel  and  received  the  documents  which  follow  this  abstract. 
With  respect  to  the  observations  in  Sir  J.  Herschel's  letter,  Mr.  Mur- 
chison says,  he  does  not  conceive  that  the  ice  caverns  at  Teneriffe,  in 
Auvergne  and  elsewhere  are  analogous  cases  with  that  at  llletzkaya 
Zatchita,  the  frozen  materials  in  the  last  not  arising  from  the  pre- 
servation of  the  snow  or  ice  of  the  preceding  winter,  but  from  the 

*  The  abundance  of  these  brine-springs  in  various  parts  of  Russia  must 
lead,  the  author  says,  to  the  abandonment  of  Pallas's  hypothesis,  that  the 
saline  pools  and  lakes  are  the  residue  of  former  Caspians  ;  though  he  admits 
that  some  of  the  vast  low  steppes  of  the  South  formed  the  bottom  of  a  for- 
mer condition  of  the  existing  Caspian. 


Sir  J.  Herschei  on  the  Phenomena  of  the  Freezing  Cave.  859 

peculiar  condition  of  the  cavern  during  the  hottest  summer  months. 
He  states  also  that  he  particularly  urged  the  authorities  at  Oren- 
burg as  well  as  the  directors  of  the  Salines  to  keep  accurate  regis- 
ters of  the  temperature  throughout  the  year,  and  to  ascertain  pre- 
cisely the  changes  which  the  cave  undergoes  between  the  extremes 
of  summer  and  winter.  There  is,  he  observes,  a  very  marked  dif- 
ference between  the  climate  of  the  steppes  south  of  Orenburg  and 
that  of  Ekaterinburg,  not  merely  due  to  the  difference  of  six  de- 
grees of  latitude,  but  arising  also  from  the  altitude  of  the  position 
of  Ekaterinburg  and  the  shortness  of  its  varying  summers  as  well 
as  from  the  long  droughty  summers  of  the  steppes,  which  are  re- 
moved from  all  mountain  chains,  and  possess  comparatively  no  great 
altitude  above  the  sea.  In  the  southern  region,  he  conceives,  a  sub- 
stratum of  frozen  matter  cannot  exist,  there  being  a  most  extraor- 
dinary difference  between  the  climate  of  Yakatsk  (lat.  62|°  N.  long. 
131°  E.)  and  that  of  Orenburg  (lat.  51°  46'  N.),  the  winter  of  the 
former  lasting  eight  or  nine  months,  with  the  thermometer  during  long 
periods  constantly  30°  and  sometimes  40°  of  Reaumur  below  zero*. 

Respecting  the  explanation  that  the  difference  of  temperature  in 
the  cave  is  due  to  the  propagation  through  the  gypsum  hillock  of 
the  heat  or  cold  of  the  preceding  summer  or  winter  season,  Mr. 
Murchison  conceives  that  the  fissures  which  ramify  from  the  cave 
into  the  hill,  present  difficulties  to  such  a  solution.  When  he  was 
on  the  spot,  the  existence  of  these  fissures  led  him  to  speculate  upon 
the  possibility  of  the  phenomena  being  due  to  currents  of  air' 
passing  over  subterranean  floors  of  moistened  rock-salt,  and  on  the 
effects  which  would  be  produced  when  such  currents  came  in  contact 
with  a  stream  of  dry  heated  air. 


LXV II.  Extractsfrom  a  letter  addressed  by  Sir  J.  Herschel, 
Bart.9  F.G.S.,  to  Mr.  Murchison,  explanatory  of  the  Phe- 
nomena of  the  Freezing  Cave  of  Illetzkaya  Zatchitaf. 

"HPHAT  the  cold  in  ice-caves  (several  of  which  are  alluded  to  in  a 
■■-  part  of  this  letter  not  published)  does  not  arise from  evaporation, 
is,  I  think,  too  obvious  to  need  insisting  on.  It  is  equally  impos- 
sible that  it  can  arise  from  condensation  of  vapour,  which  produces 
heat,  not  cold.  »  When  the  cold  (by  contrast  with  the  external  air, 

*  Mr.  Murchison  ascertained  during  his  journey  in  the  North  of  Russia 
in  1840,  that  much  remains  to  be  done  relative  to  the  circumstances  of  the 
recorded  frozen  substratum  at  Yakatsk ;  and  he  states  the  following  as  points 
requiring  attention.  1st.  With  the  exception  of  about  sixty  feet  of  alluvial 
soil,  the  whole  shaft  to  a  depth  of  350  feet  was  sunk  through  solid  strata 
of  limestone  two  to  six  feet  thick,  and  shale  with  a  little  coal ;  2ndly,  That 
none  of  the  sinkings  took  place  in  summer  although  renewed  for  several 
years,  on  account  of  the  foul  air  generated  in  the  shaft ;  3rdly,  That  when 
Admiral  Wrangel  descended  the  shaft  during  the  summer,  and  the  surface 
was  burnt  up,  he  found  the  thermometer  to  stand  at  6°  Reaum.  below  zero. 

f  From  the  Proceedings  of  the  Geological  Society,  vol.  ii.  part  2;  having 
been  read  March  9, 1842. 


360         Sir  John  Herschel  on  the  Phenomena  of  the 

i.  e.  the  difference  of  temperature)  is  greatest,  the  reverse  process 
is  going  on.  Caves  in  moderately  free  communication  with  the  air 
are  dry  and  (to  the  feelings)  warm  in  winter,  wet  or  damp  and  cold 
in  summer.  And  from  the  general  course  of  this  law  I  do  not  con- 
sider even  your  Orenburg  caves  exempt,  since  however  apparently 
arid  the  external  air  at  120°  Fahr.  !  may  be,  the  moisture  in  it  may 
yet  be  in  excess  and  tending  to  deposition,  when  the  same  air  is 
cooled  down  to  many  degrees  beneath  the  freezing  point. 

"  The  data  wanting  in  the  case  of  your  Orenburg  cave  are  the 
mean  temperature  of  every  month  in  the  year  of  the  air,  and  of  ther- 
mometers buried  say  a  foot  deep,  on  two  or  three  points  of  the  sur- 
face of  the  hill,  which  if  I  understand  you  right  is  of  gypsum  and  of 
small  elevation.  I  do  not  remember  the  winter  temperature  of 
Orenburg,  but  for  Catherinenburg  (only  5°  north  of  Orenburg), 
the  temperatures  are  given  in  Kuppfer's  reports  of  the  returns  from 
the  Russian  magnetic  observatories.  If  anything  similar  obtains  at 
Orenburg  I  see  no  difficulty  in  explaining  your  phenomenon.  Re- 
jecting diurnal  fluctuations  and  confining  ourselves  to  a  single  sum- 
mer wave  of  heat  propagated  downwards  alternately  with  a  single 
winter  wave  of  cold,  every  point  at  the  interior  of  an  insulated  hill 
rising  above  the  level  plain  will  be  invaded  by  these  waves  in  suc- 
cession (converging  towards  the  centre  in  the  form  of  shells  similar 
to  the  external  surface),  at  times  which  will  deviate  further  from 
mid-winter  and  mid-summer  the  deeper  the  point  is  in  the  interior, 
so  that  at  certain  depths  in  the  interior,  the  cold-wave  will  arrive  at 
mid-summer  and  the  heat-wave  in  mid-winter.  A  cave  (if  not  very 
wide-mouthed  and  very  airy)  penetrating  to  such  a  point  will  have 
its  temperature  determined  by  that  of  the  solid  rock  which  forms 
its  walls,  and  will  of  course  be  so  alternately  heated  and  cooled. 
As  the  south  side  of  the  hill  is  sunned  and  the  north  not,  the  sum- 
mer wave  will  be  more  intense  on  that  side  and  the  winter  less  so; 
and  thus  though  the  form  of  the  wave  will  still  generally  correspond 
with  that  of  the  hill,  their  intensity  will  vary  at  different  points  of  each 
wave-surface.  The  analogy  of  naves  is  not  strictly  that  of  the  pro- 
gress of  heat  in  solids,  but  nearly  enough  so  for  my  present  purpose. 

"  The  mean  temperature  for  the  three  winter  months,  December, 
January,  February,  and  the  three  summer  months,  June,  July,  Au- 
gust, for  the  years  1836,  7,  8,  and  the  mean  of  the  year,  are  for 
Catherinenburg  as  follows : — 


1836. 

1837. 
1838. 

Winter. 

-  10°'93  R. 

-  12°-90 

-  12°'37 

Summer. 
+  11°'90  R. 
+  12°'93 
-f-  12°-37 

Annual  Mean. 
+  l°-22  R. 
+  0°'30 
+  0°'60 

Mean. 

-  12°-07  R. 
+  4°-83  Fahr. 

+  12°-40  R. 
+  59°-9  Fahr. 

+  0'70  R. 
+  33°"57  Fahr. 

M  The  means  of  the  intermediate  months  are  almost  exactly  that 


Freezing  Cave  of  IlletzJcaya  Zatchita.  361 

of  the  whole  year,  and  the  temperature  during  the  three  winter  as 
well  as  the  three  summer  months  most  remarkably  uniform. 

"  This  is  precisely  that  distribution  of  temperature  over  time 
which  ought  under  such  circumstances  to  give  rise  to  well-defined 
and  intense  waves  of  heat  and  cold ;  and  I  have  little  doubt  there- 
fore that  this  is  the  true  explanation  of  your  phenomenon. 

"  I  should  observe,  that  in  the  recorded  observations  of  the  Ca- 
therinenburg  ohservatory,the  temperatures  are  observed  two-hourly, 
from  eight  a.m.  to  ten  p.m.,  and  not  at  night.  The  mean  monthly 
temperatures  are  thence  concluded  by  a  formula  which  I  am  not 
very  well  satisfied  with ;  but  the  error,  if  any,  so  introduced  must 
be  far  too  trifling  to  affect  this  argument.  The  works  whence  the 
above  data  are  obtained  are,  '  Observations  Meteor  ologiques  et 
Magneliques  faites  dans  Vinl&rieur  de  I' Empire  de  Russie, '  and 
'  Annuaire  Magne'tique  et  Meteor ologique  du  Corps  des  Ingenieurs 
des  Mines  de  Russie,'  works  which  we  owe  to  the  munificence  of 
the  Russian  government,  and  which  it  is  satisfactory  to  find  thus 
early  affording  proofs  of  utility  to  science  in  explaining  what  cer- 
tainly might  be  regarded  as  a  somewhat  puzzling  phenomenon, 
as  it  is  one  highly  worthy  of  being  further  studied  and  being 
made  the  subject  of  exact  thermometric  researches  on  the  spot,  and 
wherever  else  anything  similar  occurs." 

Sir  John  Herschel  then  states,  that  since  he  began  this  letter  he 
had  examined  some  old  documents  and  found  the  paper  which  ac- 
companied his  letter.  "  The  date  of  this  manuscript,"  he  adds,  '*  as 
nearly  as  I  can  collect  it  from  collateral  circumstances,  must  have 
been  somewhere  about  the  year  1829,  or  rather  before  than  after. 
"  I  remain,  &c, 

"  J.  F.  W.  Herschel. 

"  P.S.  Thermometric  observations  in  the  Steppes,  of  the  mean 
monthly  temperature  of  the  soil  at  different  depths  from  one  to  100 
feet  (at  Forbes's  intervals),  would  be  most  interesting.  At  Cathe- 
rinenburg  the  mean  temperature  of  the  air  being  38°-6  Fahr.,  no 
permanently  frozen  soil  would  probably  be  reached,  but  a  very  little 
more  to  the  northward  that  phenomenon  must  occur. 

11  The  '  thinning  out'  of  the  frozen  stratum  would  be  most  inter- 
esting to  trace,  but  in  thinning  out  by  decrease  of  latitude  it  might 
possibly  at  the  same  time  '  dip '  beyond  reach,  all  above  it  being  oc- 
cupied by  soil  subject  to  the  law  of  periodic  frost  and  thaw,  and 
giving  room  under  favourable  circumstances  to  ice-caverns,  pits,  or 
galleries.  What  determines  the  distinct  definition  of  the  hot  and 
cold  alternating  layers  is  the  exceedingly  peculiar  form  of  the  curve 
of  the  monthly  temperatures  as  given  in  the  tables  above  referred  to." 


Phil.  Mag.  S.  3.  Vol.  21.  No.  139.  Nov.  1842.       2  B 


[     362     ] 

LXVIII.  On  some  Phenomena  observed  on  Glaciers,  and  on 
the  internal  temperature  of  large  Masses  of  Ice  or  Snow,  with 
some  Remarks  on  the  natural  Ice-caves  which  occur  below 
the  limit  of  perpetual  Snow.  By  Sir  John  Herschel, 
Bart.,  F.G.S.,  $c* 
IN  a  visit  to  the  glacier  of  Chamouni  in  the  summer  of  1821, 1  was 
■*-  struck  with  the  very  remarkable  positions  of  several  large  blocks 
of  granite  resting  on  the  glacier  in  various  parts.  They  were  perched 
on  stools  of  ice  of  less  diameter  than  the  blocks  themselves,  which 
overhang  their  supports  on  all  sides,  as  a  mushroom  does  its  stalk. 
The  position  of  these  large  masses  was  rendered  the  more  striking 
when  contrasted  with  that  of  small  fragments  of  stone,  equally  (to 
appearance)  exposed  to  all  the  local  heating  and  cooling  influences, 
but  which  were  uniformly  found  to  have  sunk  into  the  ice,  and 
that  the  deeper,  (within  certain  limits)  the  less  their  size.  On  con- 
sideration, the  cause  became  apparent,  and,  as  it  affords  a  very 
pretty  illustration  of  the  laws  of  the  propagation  of  heat  through 
bad  conductors,  and  the  steps  by  which  an  average  temperature  is 
attained  in  large  masses  from  a  varying  source,  I  will  here  state  it 
as  it  occurred  to  me  at  the  time. 

With  regard  to  the  sinking  of  small  masses  into  the  ice  when 
heated  by  the  sun,  it  is  the  natural  effect  of  the  greater  power  of 
absorbing  heat  which  stone  possesses  beyond  ice.  Whenever  the 
sun  shines,  the  stone  will  detain  more  of  its  heat  than  an  equal  sur- 
face of  ice  would  do  ;  and  as  it  gives  this  out  to  the  ice  below  nearly 
as  fast  as  it  receives  it,  a  greater  depth  of  ice  is  melted  in  a  given 
time  beneath  the  stone  than  in  the  parts  around.  On  the  other  hand, 
at  night,  ice  radiates  terrestrial  heat  nearly  or  quite  as  copiously  as 
stone,  and  thus  they  are  on  a  par  in  frigorific  power. 

The  elevation  of  great  masses  above  the  general  level,  which  at 
first  sight  would  appear  to  contradict  this  explanation,  is  however 
equally  a  consequence  of  the  laws  of  the  propagation  of  heat.  To 
conceive  this,  let  us  imagine  a  very  large  block  of  stone,  at  the  com- 
mencement of  the  summer,  to  lie  on  a  level  surface  of  ice,  in  a  si- 
tuation exposed  to  the  direct  rays  of  the  sun,  where  the  mean  tem- 
perature of  day  and  night  is  (even  in  summer)  but  little  above  the 
freezing-point,  but  where,  however,  no  fresh  snow  falls  during  the 
whole  summer.  In  the  day  time  then,  while  receiving  the  sun's 
rays,  the  upper  surface  of  the  stone  will  be  strongly  heated,  and  a 
wave  of  heat  will  be  propagated  slowly  downwards  through  the 
stone  towards  the  ice,  diminishing  in  intensity  rapidly,  however,  as 
it  travels,  since  each  superior  stratum  only  divides  its  excess  of 
temperature  with  that  below.  Long  before  this  can  reach  the  ice, 
however,  night  comes  on.  The  surface  cools  below  the  mean  or 
even  below  the  actual  temperature  of  the  air  by  radiation,  and  a 
wave  of  cold  is  propagated  (or,  which  comes  to  the  same  thing,  heat 
is  abstracted  from  stratum  to  stratum)  by  the  same  laws.    This  fol- 

*  From  the  Proceedings  of  the  Geological  Society,  vol.  ii.  part  2 ;  having 
been  read  March  9, 1842. 


Sir  J.  Herschel  on  some  Phenomena  on  Glaciers,  fyc.    363 

lows  close  on  the  wave  of  heat  below  and  travels  with  equal  velo- 
city. In  consequence,  the  heated  stratum  parts  with  its  heat,  now, 
both  upwards  and  downwards,  and  thus  the  intensity  of  the  wave  of 
heat  diminishes  with  much  greater  rapidity  as  it  proceeds  down- 
wards. It  is  manifest,  that  were  the  thickness  of  the  stone  infinite, 
the  wave  of  heat  being  always  followed  close  up  by  the  wave  of 
cold,  and  a  perpetual  tendency  to  an  equilibrium  of  temperature 
going  on  between  them,  they  would  ultimately  reduce  each  other  to 
their  mean  quantity  and  (not  to  take  the  extreme  case  of  infinity) 
at  some  very  moderate  depth,  the  fluctuations  above  and  below  the 
mean  temperature  of  the  air,  as  the  successive  nocturnal  and  diur- 
nal waves  pass  through  a  particle  of  the  stone  there  situated,  will  be 
rendered  very  trifling,  and  may  for  our  present  purpose  be  regarded 
as  evanescent.  Beyond  this  depth,  whatever  mass  of  stone  may 
exist,  may  be  regarded  as  a  slow  conducting  mass,  interposed  be- 
tween a  surface  of  ice  constantly  maintained  at  32°,  and  a  surface 
of  stone  constantly  maintained  at  the  mean  temperature  of  the  air, 
which  by  hypothesis  is  very  little  above  it.  Through  this  then  the 
heat  will  percolate  uniformly  but  feebly,  and  the  ice  below  will  be 
very  slowly  melted,  and  the  more  so  in  proportion  to  the  thickness 
of  the  interposed  stratum.  Let  us  now  consider  what  happens  to 
the  ice  on  the  parts  undefended  by  the  stone.  In  the  day  time  these 
experience  the  direct  radiation  of  the  sun,  and  therefore  melt  and 
run  off  in  water.  At  night,  it  is  true,  the  remaining  surface  cools 
by  radiation ;  but  this  cold  is  propagated  downwards,  and  on  the 
return  of  day  the  superficial  lamina  is  necessarily  put  in  equilibrium 
with  the  air  and  melted  by  the  sun,  and  however  cold  the  interior  of 
the  mass  may  be,  the  surface  will  still  be  kept  all  day  in  a  state  of 
fusion.  Thus  the  degradation  of  the  general  surface  of  the  ice  will 
be  in  proportion  to  the  direct  intensity  of  the  sun's  rays  and  the  time 
they  shine,  while  that  of  the  surface  beneath  the  stone  will  only  be 
in  proportion  to  the  excess  of  the  mean  temperature  of  day  and  night 
above  32°,  diminished  by  the  effect  of  the  thickness  of  the  stone. 
This  of  course  will  produce  a  difference  of  level,  and  a  relative  ele- 
vation of  the  stone  sunk  as  really  observed.  One  curious  and,  at 
at  first  sight,  paradoxical  consequence  seems  to  follow  from  this 
reasoning,  viz.  that  the  ice  of  a  glacier,  or  other  great  accumulation 
of  the  kind,  may,  at  some  depth  beneath  the  surface,  have  a  per- 
manent temperature  very  much  below  freezing,  though  in  a  situa- 
tion whose  mean  annual  temperature  is  sensibly  above  that  point. 
In  fact  (continuing  to  use  the  metaphorical  expression  already  em- 
ployed), there  is  no  reason  why  waves  of  cold,  of  any  intensity  be- 
low 32°,  may  not  be  propagated  downwards  into  the  interior  of  the 
ice ;  but  waves  of  heat  above  that  point,  of  course,  never  can.  Thus, 
the  cold  of  winter  and  the  frost  produced  by  radiation  in  the  clear 
nights  of  summer,  will  enter  the  mass  and  lower  its  internal  tempe- 
rature, while  the  heat  of  the  summer  air  and  that  imparted  by  solar 
radiation  will  mainly  be  employed  in  melting  the  surface,  and  will 
run  off  with  the  water  produced. 

2  B  2 


864     Sir  J.  Herschel  on  some  Phenomena  on  Glaciers,  SfC. 

I  am  not  aware  of  any  observations  on  the  internal  temperature 
of  glaciers — they  are  of  course  difficult  from  their  usual  rifty  state  ; 
but  the  point  may  not  be  unworthy  the  attention  of  the  scientific 
traveller.  May  not  this  be  the  cause  of  those  natural  formations  of 
ice  which  have  been  observed  in  caverns,  in  Teneriffe,  and  on  some 
elevated  points  of  the  Jura  chain,  below  the  level  of  perpetual  snow  ? 
It  is  obviously  no  matter  whether  the  interior  mass  in  the  above 
reasoning  be  ice  or  rock.  It  is  enough,  that  its  surface,  during  the 
whole  or  great  part  of  the  year,  should  be  covered  with  ice  to  bring 
down  the  mean  annual  temperature  of  its  interior  materially  below 
the  temperature  due  to  its  elevation,  and  which  it  would  have  were 
it  not  so  covered.  Conceive  now  a  mountain  whose  summit  is  in 
this  predicament,  viz.  constantly  maintained  at  a  mean  temperature 
below  that  due  to  its  elevation.  This  intense  cold  will  not  break  off' 
at  the  level  of  the  line  of  perpetual  snow,  which  is  determined  by 
the  mean  temperature  of  the  atmosphere  due  to  elevation,  but  will 
be  propagated  downwards  in  the  interior  of  its  mass.  Hence,  if  at 
a  short  distance  below  the  line  of  perpetual  snow,  where  the  mean 
diurnal  temperature  of  the  exposed  part,  taken  at  a  few  feet  or  a  few 
yards  deep  in  the  soil  or  rock,  is  a  little  above  freezing,  we  drive  an 
adit,  or  take  advantage  of  a  natural  fissure  to  obtain  the  internal 
temperature  at  a  much  greater  depth  from  the  surface  ;  we  ought  to 
find  it  below  32°,  and  ice  ought  constantly  to  form  in  such  cavities. 
But  even  when  the  summit  of  a  hill  is  not  covered  with  ice,  and 
when  therefore  this  particular  principle  does  not  apply,  it  is  easy  to 
see,  on  the  same  general  grounds,  that  something  of  the  same  kind 
may  obtain.  It  is  obvious,  that  whenever  a  change  of  temperature  on 
the  surface  of  a  solid  takes  place,  a  wave  of  heat  or  cold,  as  the  case 
may  be,  will  be  propagated  through  its  substance  ;  and  if  the  changes 
be  regularly  periodic,  the  waves  will  be  also.  Moreover  it  is  clear 
that  the  longer  the  periods  of  the  external  fluctuations  are  supposed, 
the  greater  will  be  the  interval  of  the  waves,  so  as  to  make  the 
time  taken  for  the  propagated  heat  to  run  over  them  precisely  equal 
to  the  period  of  fluctuation.  Now  the  rapidity  with  which  succes- 
sive waves  of  heat  and  cold  destroy  each  other,  is  inversely  as  the 
intervals,  and  thus  the  fluctuations  of  temperature  depending  on 
long  periods  of  external  change  will  be  propagated  to  greater  depths 
than  those  arising  from  shorter  periods,  nearly  in  the  ratio  of  the 
lengths  of  the  periods.  Thus  the  depths  at  which  the  annual  fluc- 
tuations of  temperature  cease  to  be  sensible,  will  be  between  300  and 
400  times  greater  than  those  at  which  the  diurnal  ones  are  neutral- 
ized. Now  it  may  happen,  from  the  slowness  of  propagation  through 
so  considerable  a  depth,  that  the  winter  wave  of  cold  (consisting  of 
many  diurnal  waves  of  alternate,  greater  and  less  intensity)  may  not 
travel  down  to  the  adit  or  cavern  till  the  hottest  period  of  the  next 
summer,  or  of  many  summers  ;  in  short,  that  if  at  any  given  time 
the  interior  of  the  mountain  were  sounded  by  thermometers  down  its 
whole  axis,  these  instruments  would  exhibit  alternate  deviations  + 
and  —  from  the  mean  temperature  of  the  air. 


[     365     ] 
LXIX.    Proceedings  of  Learned  Societies. 

GEOLOGICAL  SOCIETY. 

[Continued  from  p.  309.] 

Dec.  1,  A  paper  was  first  read,  entitled,  "Report  of  the  Destruc- 
1841.  -t\.  tion  by  Earthquake  of  the  Town  of  Praya  de  Victoria, 
on  the  15th  of  June,  1841."  By  Mr.  Consul  Hunt;  communicated 
by  direction  of  the  Right  Hon.  the  Foreign  Secretary  of  State. 

't he  town  of  Praya  stood  at  the  east  end  of  the  island  of  Terceira, 
and  contained  562  houses ;  near  it  were  the  villages  of  Lageas  (523 
houses),  Villa  Nova  (206  houses),  Agoalva  (244  houses),  Fontinha 
(203  houses),  and  Fonte  do  Bastardo  (144  houses),  the  total  popula- 
tion being  about  9000  souls.  The  town  of  Praya  had  been  on  a 
former  occasion  (1614)  totally  destroyed  by  an  earthquake,  and 
Angra,  the  capital  of  the  island,  situated  twelve  English  miles 
distant,  was  considerably  injured,  the  shocks  being  severely  felt 
in  the  island  of  St.  Michael.  Although  menaced  during  many 
earthquakes,  Praya  had  escaped  injury  from  that  time  till  the  12th 
of  June  1841,  when,  at  4  p.m.,  a  violent  shock  was  felt,  and  with 
diminished  force  to  the  westward.  At  twenty-five  minutes  past 
five,  a  second,  more  powerful  shock  was  experienced,  and  through- 
out the  13th  of  June,  tremblings  were  felt  at  short  intervals.  At 
4  a.m.  on  the  14th  a  perfectly  perceptible  undulation  destroyed  all 
those  buildings  which  had  been  previously  weakened,  but  during  the 
remainder  of  that  day  the  island  was  visited  by  only  occasional  slight 
shocks.  On  the  15th,  at  3  a.m.,  violent  tremblings  and  horizontal 
undulations  of  the  ground  commenced,  and  continued,  with  intervals 
of  ten  minutes,  and  a  duration  of  about  10  seconds,  until  30  minutes 
past  3  o'clock,  when  a  strong,  vibrating  and  distinctly  visible  rocking 
motion  was  communicated  to  the  surface,  and  threw  down  the  un- 
destroyed  portion  of  Praya,  several  churches  and  houses  of  the  adja- 
cent villages,  and  considerably  injured  the  remainder,  as  well  as 
many  elevated  public  buildings  in  other  parts  of  the  island.  The 
ground  then  remained  comparatively  at  rest  until  40  minutes  past  2 
a.m.  on  the  16th,  when  a  violent  earthquake  did  further  damage; 
but  from  that  period  no  additional  injury  was  sustained,  though  the 
island  did  not  resume  a  permanently  quiescent  state  till  the  26th  of 
June.  The  number  of  houses  thrown  down  is  estimated  to  be  800, 
but  several  others  must  be  rebuilt,  and  of  the  remainder  the  greater 
number  require  extensive  repairs. 

During  the  whole  of  these  earthquakes  the  motion  was  greatest  at 
Praya,  diminishing  in  force  to  the  westward,  and  every  convulsion 
was  preceded  by  a  loud  subterranean  or  submarine  noise  to  the  east- 
ward of  Terceira,  which  so  exactly  varied  in  intensity  with  the  force 
of  the  succeeding  shocks,  that  the  noise  became  not  only  the  harbinger 
but  the  measure  of  the  severity  of  the  earthquake.  A  rent  an  English 
mile  in  length  was  formed  in  the  ground,  extending  from  the  shore 
to  the  westward. 

The  less  severe  shocks  were  not  felt  beyond  Terceira :  others  were 


366  Geological  Society  :  the  Rev:  R.  Everest's 

experienced,  of  apparently  equal  force,  at  St.  George's,  about  fifty 
miles  to  the  south-west,  and  at  Graciosa,  about  the  same  distance  to 
the  north-west  of  Praya ;  but  only  the  earthquake  which  destroyed 
that  town  was  felt,  though  not  powerfully,  at  the  capitals  of  Pico, 
sixty-eight  miles  south-west,  and  of  St.  Michael's,  the  same  distance 
to  the  south-east.  At  Fayal,  eighty-five  miles  west  by  south,  and  at 
the  eastern  end  of  St.  Michael's,  105  miles  south-east  by  east,  no  mo- 
tion was  perceived,  as  far  as  Mr.  Consul  Hunt  had  been  able  to  ascer- 
tain. If  the  shocks  felt  about  30  minutes  past  3  o'clock  on  the 
morning  of  the  15th  of  June,  in  the  several  islands,  be  divided  into 
four  degrees  of  intensity,  each  interval,  the  author  says,  will  be 
found  to  contain  a  distance  of  about  seventeen  miles,  the  eastern 
end  of  Terceira  being  on  the  first  degree,  or  seventeen  miles  from 
the  centre  of  eruption  ;  the  western  end  thirty-four  miles  ;  Graciosa 
and  St.  George's  fifty-one,  and  the  capitals  of  Pico  and  St.  Michael's 
sixty-eight  miles.  The  latter  places,  equally  distant  from  the  centre 
of  eruption,  experienced  shocks  of  equal  degrees  of  diminished 
force. 

Mr.  Consul  Hunt  then  alludes  to  Buffon's  notice  of  submarine  ex- 
plosions between  St.  Michael's  and  Terceira,  attended  by  earthquakes 
in  those  islands,  and  the  appearance  of  newly  formed  islets  ;  also  to 
the  throwing  up  of  Sabrina,  near  St.  Michael's,  in  1811*,  the  effects 
of  which  were  powerfully  felt  in  that  island,  but  not  in  Terceira, 
fifty  miles  distant ;  and,  on  account  of  these  phaenomena,  he,  in 
conclusion,  advises  mariners  to  keep  a  sharp  look-out  for  shoal  water 
on  approaching  Terceira  from  the  eastward. 

A  paper,  entitled  "  Some  Geological  Remarks  made  in  a  Journey 
from  Delhi,  through  the  Himalaya  Mountains,  to  the  frontier  of 
Little  Thibet,  during  1837,"  by  the  Rev.  Robert  Everest,  F.G.S., 
was  then  read. 

The  author's  route,  after  quitting  Delhi,  lay  through  Seharun'- 
pore,  the  Keeree  pass  in  the  Sevalik  hills,  and  Mussoori  to  the  Jumna, 
thence  nearly  north-west  to  the  valley  of  the  Paber,  as  far  as  Roo- 
roo,  where  it  quitted  the  course  of  that  river  and  crossed  the  moun- 
tain range  to  Rampore.  It  then  ascended  the  valley  of  the  Sutluj 
to  the  Leo  River,  and  terminated  near  the  Khealkhur  Fort,  on  the 
frontier  of  Little  Thibet.  The  country  consists  of  alluvial  deposits, 
the  tertiary  strata  of  the  Sevaliks,  a  vast  sandstone  deposit,  an  ex- 
tensive clay-slate  formation  containing  limestone  and  sandstone, 
various  metamorphic  rocks,  greenstone  and  granite. 

Delhi  is  situated  on  the  most  northern  promontory  of  an  extensive 
sandstone  formation,  which  stretches  many  miles  in  a  south-west  and 
south-east  direction,  following  the  course  of  the  Jumna,  and  re- 
sembles, in  mineral  characters,  the  transition  quartzose  sandstones 
of  Europe.  It  alternates,  though  rarely,  with  layers  of  soft  talc  slate, 
and  a  few  miles  to  the  southward  of  Delhi  with  clay  slate.  To  the 
south-west,  a  little  beyond  Goongony,  and  in  other  localities,  sienitic 

[*  An  original  letter  on  the  elevation  of  Sabrina  appeared  in  Phil.  Mag., 
S.  1.  vol.  xxxviii.  p.  229,  and  a  reprint,  from  the  Philosophical  Transac- 
tions, of  Capt.Tillard'8  narrative  respecting  it,  in  vol.  xxxix.  p.  451. — Edit.] 


Geological  Remarks  made  in  a  Journey  in  India.    367 

rocks  are  connected  with  it.  No  fossil  remains  have  heen  discovered 
in  the  formation.  At  Delhi  the  strata  are  highly  inclined  towards 
the  east-south-east. 

From  Delhi  to  beyond  Seharunpore,  a  distance  of  more  than  100 
miles,  the  surface  of  the  country  consists  of  a  fine  sandy  soil,  and 
contains  nodules  of  kunkur,  similar  to  alluvial  granitic  or  primary 
detritus  brought  down  by  the  Jumna.  Beyond  Seharunpore  the 
tertiary  beds  of  the  Sevalik  range  commence ;  but  Mr.  Everest  alludes 
to  their  mammalian  remains  only  for  the  purpose  of  remarking,  that 
no  portions  of  the  wild  elephant,  which  now  abounds  in  that  district, 
have  been  found  in  the  tertiary  strata ;  and  he  quotes,  as  an  analo- 
gous case,  the  absence  of  the  bones  of  the  Asiatic  elephant  in  the 
mammalian  deposits  of  the  Irawaddi.  From  these  facts  he  infers 
that  the  present  species  did  not  co-exist  with  the  Elephas  primige- 
nius,  the  mastodon,  or  the  associated  mammifers. 

The  chain  of  the  Himalayas,  which  rises  like  a  black  wall  on  the 
opposite  of  the  valley  of  the  Dhoon,  or  that  which  separates  it  from 
the  Sevalik  hills,  consists,  where  crossed  by  the  author  (about  77° 
55'  E.  long.),  of  strata  highly  inclined  to  the  north-east,  and  com- 
posed of  dark  blue  or  variegated  clay  slate,  sometimes  sufficiently 
hard  to  be  used  for  roofing  slates,  but  generally  soft,  of  compact, 
dark  blue  and  black  carbonaceous  limestone,  and  of  highly  conso- 
lidated quartzy  sandstone  resembling  that  near  Delhi.  No  organic 
remains  have  been  noticed  in  these  beds.  Dykes  of  greenstone  con- 
taining diallage  were  observed  by  the  author. 

From  Mussoori*  (lat.  30°  25',  long.  77°  55'  E.),  Mr.  Everest  de- 
scended to  the  Jumna,  over  beds  similar  to  those  just  described,  and 
of  slate  containing  angular  fragments.  In  the  bed  of  the  river  the 
strata  are  very  much  disturbed.  Beyond  the  Jumna  the  rocks  con- 
sist of  purplish  clay  slate,  often  passing  into  quartz  slate  and  talc 
slate.  The  general  dip  is  to  the  north-east,  but  the  angle  of  incli- 
nation is  stated  to  vary  from  nearly  horizontal  to  vertical.  Beyond 
the  village  of  Luchwarree,  not  far  from  the  Jumna,  occur  blocks  of 
greywacke  similar  to  those  observed  in  the  descent  to  that  river. 
Thence  to  the  heights  of  Deobun,  the  most  lofty  point  between  the 
Jumna  and  the  Tonse  (lat.  about  30°  47',  long,  about  77°  48'  E.), 
the  strata  present  little  variety,  but  the  last  2000  feet  of  ascent  con- 
sist of  rugged,  black  and  grayish  blue  limestone,  similar  to  that  at 
Mussoori.  The  descent  towards  the  Tonse  exhibits  slates  similar  to 
those  previously  described,  dipping  between  north  and  east.  They 
are  occasionally  intersected  by  greenstone  containing  pistacite,  and 
passing  in  some  places  into  hornblende  slate  and  serpentine.  At  the 
village  of  Kundah,  before  reaching  the  Tonse,  limestone  reappears, 
highly  inclined  to  the  north-east,  and  extends  to  the  bridge.  The 
bed  of  the  Tonse,  and  of  its  tributary  the  Paber,  are  filled  with 
boulders  of  gneiss,  and  they  occur  at  heights  of  200  feet  above  those 
rivers.     The  slate  rocks,  in  ascending  the  river-valleys,  change  in 

*  The  degrees  of  latitude  and  longitude  given  in  this  abstract  must  be 
considered  only  as  approximations. 


368  Geological  Society :  the  Rev.  R.  Everest's 

their  composition  from  that  previously  exhibited ;  containing,  first, 
frequently  nodules  and  layers  of  quartz,  and,  though  rarely,  of  fel- 
spar, and  afterwards  passing  into  well-defined  gneiss  ;  and  still  fur- 
ther, as  at  Raeenghur  and  Rooroo,  different  varieties  of  gneiss  alter- 
nate with  talc-slate,  quartzose  slate  and  mica  slate.  This  progress- 
ive change,  from  the  party-coloured  earthy  slates  of  Mussoori  to 
crystalline  schists,  on  approaching  the  higher  ranges  of  mountains 
covered  with  perpetual  snow,  perfectly  accords,  Mr.  Everest  states, 
with  what  he  had  previously  observed  in  two  journeys  to  the  sources 
of  the  Ganges  and  the  Jumna.  The  dip  of  the  beds  in  the  valleys  of 
the  Tonse  and  Paber  is  to  the  north-east. 

At  Rooroo  Mr.  Everest  quitted  the  course  of  the  Paber  and 
crossed  the  mountain  range  to  the  valley  of  the  Sutluj.  The  highest 
point  which  he  attained  on  this  ridge  was  only  8000  feet  above  the 
level  of  the  sea,  and  it  was  then,  the  middle  of  April,  nearly  free  from 
snow.  From  the  view  which  this  pass  afforded,  the  author  ascer- 
tained that  the  country  shelves  or  declines  from  the  north-east  to  the 
south-west,  the  mountains  between  the  north  and  east  rising  far  above 
the  limits  of  forests  and  being  white  with  snow,  while  among  those 
to  the  westward  or  southward  few  peaks  appeared  above  the  range 
of  forests,  and  little  snow  was  seen.  The  rocks  composing  this  moun- 
tain range  consist  near  Rooroo  of  mica  slate,  with  a  very  slight  dip  to 
the  east  and  south-east,  but  the  inclination  of  the  beds  in  ascending 
towards  the  pass  becomes  considerable,  but  in  the  same  direction. 
North  of  Kersole  (lat.  31°  25',  long.  77°  33'  E.)  gneiss  appears  dipping 
south  and  south-east,  and  approaching  occasionally  granite  in  cha- 
racter. This  rock  ranges  half  way  to  the  Sutluj,  where  black,  com- 
pact limestone,  and  black,  glimmering,  soft  slate  are  exposed.  Near 
the  junction  of  the  Nuggur  with  the  Sutluj,  strata  of  crystalline, 
white  quartz  slate  dip  to  the  south,  and  are  traversed  by  a  mass  of 
greenstone,  which  first  rises  vertically  through  the  strata,  then  passes 
horizontally  between  them,  and  finally  bursts  upwards  and  projects 
above  the  surface.  Where  the  position  of  the  greenstone  conforms  to 
the  bedding  of  the  slate,  the  lamina;  of  mica  and  hornblende  assume 
a  similar  arrangement,  and  where  the  greenstone  intersects  the  slate, 
those  minerals  have  a  position  vertical  to  it.  A  gradual  passage  from 
greenstone  into  the  quartz  slate  was  likewise  noticed  by,  the  author. 
About  two  miles  below  Rampore  (lat.  31°  34',  long.  77°  30'), 
in  the  valley  of  the  Sutluj,  quartz  slate  alternates  with  chlorite 
slate  and  talc  slate,  the  dip  being  to  the  west  and  south-west  at  a 
considerable  angle.  Above  Rampore  the  rocks  first  consist  of  alter- 
nations of  white  quartz  slate  and  clay  slate,  the  strata  being  much 
disturbed ;  and  afterwards  of  talc  slate  associated  with  greenstone  or 
hornblende  rock,  dipping  north-east.  Before  reaching  Seran,  gneiss 
containing  kyanite  appears,  and  extends  with  occasionally  interve- 
ning masses  of  granite  to  Nasher  (lat.  31°  47',  long.  77°  46'  E.). 
On  the  opposite  side  of  the  river  at  that  place  are  precipices  of 
slate  traversed  by  white  veins ;  but  at  the  bridge,  a  large-grained 
white  granite  with  tourmalines  appears,  and  extends,  in  connexion 
with  mica  slate  and  gneiss  intersected  by  granite  veins,  seven  days' 


Geological  Remarks  made  in  a  Journey  in  India.     369 

journey  to  Akbah  (lat.  31°  56',  long.  78°  8'  E.).  At  this  village 
granite  also  occurs,  but  separated  from  that  rock  by  a  narrow 
ravine  is  a  low  promontory  of  clay  slate  and  dark  flinty  slate  dip- 
ping to  the  north.  Beyond  Akbah  the  Sutluj  bends  to  the  north, 
and  on  both  sides  of  the  river  the  outline  of  the  rocks  is  considerably 
softened  in  consequence  of  their  being  evidently  composed  of  perish- 
able clay  slate  similar  to  that  at  Mussoori ;  but  in  the  more  distant 
ranges,  granite,  mica  slate  and  gneiss  may  be  detected  by  the  rugged 
outline  and  the  great  height  of  the  rocks.  This  clay  slate,  Mr. 
Everest  says,  is  not  of  later  origin  than  the  granite  and  crystalline 
schists,  because  it  is  penetrated  by  veins  of  granite  which  may  be 
traced  to  the  great  masses  of  that  formation.  The  dip  of  the  slate 
on  one  side  of  the  river  is  west,  and  on  the  opposite  apparently  east. 
Beyond  Lipi,  a  few  miles  from  Akbah,  are  precipices  of  clay  slate, 
talc  slate,  and  dark  flinty  slate  interstratified  with  greenstone. 
After  quitting  Khanum  the  country  becomes  still  more  desolate,  and 
the  strata  consist,  first  of  earthy  slate,  in  some  places  carbonaceous, 
in  others  brecciated,  then  of  greyish  green  highly  consolidated  green- 
stone, and  afterwards  of  masses  of  blackish  and  brownish  grey  com- 
pact limestone.  The  valley  of  the  Namkulling,  a  small  tributary  of 
the  Sutluj,  presents  a  fine  section  of  these  strata,  the  upper  part 
being  composed  of  the  limestone  and  the  lower  of  the  slate.  The 
dip  from  Khanum  is  between  west  and  south-west.  From  Seenum 
(lat.  32°5',long.  78°  16'E.)  Mr.  Everest  proceeded  across  theHun- 
gung  pass,  14,837  feet  above  the  sea.  The  ground  being  covered  with 
snow,  little  of  the  structure  of  the  country  was  visible,  but  projecting 
strata  of  reddish  brown  compact  limestone  appeared  on  the  crest  of 
the  hill.  The  view  northward  presented  bare  rocks  as  far  as  the  eye 
could  reach,  but  from  the  softness  of  the  outlines,  Mr.  Everest  infers, 
that  the  strata  belong  to  secondary  or  tertiary  deposits.  Rugged 
ridges  of  primary  rocks  resembling  dykes  cross  this  dreary  expanse. 
Beyond  Hango  (lat.  32°  12',  long.  38°  18'  E.)  beds  of  reddish  and 
greenish  grey  compact  limestone  alternate  with  earthy  and  car- 
bonaceous shale,  the  dip  being  to  the  north-west,  and  blocks  of 
greyish  quartzose  sandstone  are  scattered  over  the  surface.  These 
appearances  extend  to  the  heights  above  Leo,  where  the  earthy  shales 
are  traversed  by  veins  and  layers  of  granite,  and  at  the  point  of 
contact  are  changed  into  mica  slate.  In  the  descent  to  the  village, 
nearly  2000  feet,  the  granite  veins  gradually  increase  in  number,  pre- 
dominating in  the  lower  parts ;  and  the  associated  rocks  become  more 
and  more  crystalline,  so  that  near  the  river  nothing  is  visible  but 
mica  slate,  gneiss,  quartz  slate  and  granular  limestone,  the  strata 
dipping  to  the  south-west.  Beyond  Leo  (lat.  32°  18',  long.  78°  17'E.) 
the  road  ascends  over  granite  and  dark  mica  slate,  containing  kyanite 
and  pistacite ;  but  the  earthy  strata  are  stated  to  occur  at  higher  levels. 
On  the  opposite  side  of  the  river  is  a  section  several  thousand  feet  in 
vertical  dimensions  intersected  by  a  net- work  of  granite  veins  and 
crossed  by  black  stains  derived  from  the  carbonaceous  layers.  On 
opening  on  the  hollow  in  which  the  village  of  Change  is  situated 
earthy  strata  again  appear.    This  point  was  the  boundary  of  Mr. 


370         Geological  Society :  Prof.  Owen's  Description 

Everest's  journey,  and  he  was  prevented  from  examining  the  locality 
which  produces  the  Ammonites  and  other  fossils  obtained  by  Dr. 
Gerard ;  but  he  believes,  from  the  information  supplied  by  the  natives, 
that  they  are  met  with  abundantly  beyond  the  frontier,  imbedded 
in  black  compact  limestone  and  earthy  carbonaceous  shale.  Mr. 
Everest  further  states,  that  since  his  journey  Captain  Hutton  has 
discovered  them  within  the  frontier. 

In  the  course  of  the  memoir  the  author  mentions  having  seen  at 
Seenum  the  skin  of  a  "  leopard  "  recently  killed  near  the  village, 
though  large  quantities  of  snow  were  then  (May)  lying  upon  the 
ground,  and  that  he  has  frequently  observed  in  February  and  March 
their  tracks  on  the  snow  as  high  as  the  limit  of  the  forests.  He 
also  states  that  he  has  observed  monkeys  at  the  height  of  full  8000 
feet  above  the  sea  in  the  same  months  when  the  ground  was  co- 
vered deep  with  snow,  feeding  in  great  numbers  on  the  seeds  of  the 
fir  cones. 

A  paper  was  afterwards  read  containing  a  "  Description  of  the  Re- 
mains of  Six  Species  of  Marine  Turtles  (Chelones)  from  the  London 
Clay  of  Sheppey  and  Harwich."  By  Richard  Owen,  Esq.,  F.R.S., 
F.G.S.,  Hunterian  Professor  in  the  Royal  College  of  Surgeons. 

The  author  commences  by  quoting  the  generalizations  given  in 
the  latest  works  which  treat  of  Fossil  Chelonians,  and  examines  the 
evidence  on  which  those  from  the  Eocene  day  of  Sheppey  had  been 
referred  exclusively  to  the  freshwater  genus  Emys  by  Cuvier  and 
others,  and  he  points  out  the  circumstances  which  invalidate  the 
conclusions  that  had  been  deduced  from  it.  He  then  proceeds  to 
describe  the  fossils  and  to  show  the  characters  by  which  he  has 
established  the  existence  of  five  species  of  marine  turtles  from  the 
London  Clay  at  Sheppey,  and  a  sixth  species  from  the  same  forma- 
tion near  Harwich. 

1 .  Chelone  breviceps. — The  first  species,  found  at  Sheppey,  is  called 
by  the  author  Chelone  breviceps,  and  its  unequivocal  marine  nature 
was  recognised  by  a  nearly  perfect  cranium,  wanting  only  the  occipital 
spine,  and  presenting  a  strong  and  uninterrupted  roof,  extended 
from  the  parietal  spine  on  each  side  over  the  temporal  openings  ;,  the 
roof  being  formed  chiefly  by  a  great  development  of  the  posterior 
frontals.  Further  evidence  of  its  marine  origin  exists  in  the  large 
size  and  lateral  aspect  of  the  orbits,  their  posterior  boundary  extend- 
ing beyond  the  anterior  margin  of  the  parietals  ;  also  in  the  absence 
of  the  deep  emargination  which  separates  the  superior  maxillary  from 
the  tympanic  bone  in  freshwater  tortoises,  especially  the  Emys 
expansa. 

In  general  form  the  skull  resembles  that  of  the  Chelone  Mydas,  but 
it  is  relatively  broader,  the  anterior  frontals  are  less  sloping,  and  the 
anterior  part  of  the  head  is  more  vertically  truncate :  the  median 
frontals  also  enter  into  the  formation  of  the  orbits  in  rather  a  larger 
proportion  than  in  C.  Mydas.  In  Chelone  imbricata  they  are  wholly 
excluded  from  the  orbits. 

The  trefoil  shape  of  the  occipital  tubercle  is  well-marked;  the 
laterally  expanded  spinous  plate  of  the  parietal  bones  is  united  by  a 


of  the  Remains  of  Marine  Turtles  from  the  London  Clay.    371 

straight-  suture  to  the  post-frontals  along  three-fourths  of  its  extent, 
and  for  the  remaining  fourth  with  the  temporal  or  zygomatic  ele- 
ment. 

These  proportions  are  reversed  in  the  Emys  expansa,  in  which  the 
similarly  expanded  plate  of  the  parietals  is  chiefly  united  laterally 
with  the  temporal  hones.  In  other  freshwater  tortoises  the  parietal 
plate  in  question  does  not  exist. 

The  same  evidence  of  the  affinity  of  the  Sheppey  Chelonite  in 
question  to  the  marine  turtles  is  afforded  by  the  base  of  the  skull : — 
the  basi-occipital  is  deeply  excavated ;  the  processes  of  the  pterygoids 
which  extend  to  the  tympanic  pedicles  are  hollowed  out  lengthwise ; 
the  palatal  processes  of  the  superior  maxillary  and  palatine  bones  are 
continued  backwards  to  the  extent  which  characterizes  the  existing 
Cheloniae ;  and  the  posterior  or  internal  opening  of  the  nasal  passages 
is,  in  a  proportional  degree,  carried  further  back  in  the  mouth.  The 
lower  opening  of  the  zygomatic  spaces  is  wider  in  the  Sheppey  Che- 
lonite than  in  the  Emys  expansa. 

The  external  surface  of  the  cranial  bones  in  the  fossil  is  broken  by 
small  irregular  ridges,  depressions,  and  vascular  foramina,  which  give 
it  a  rough  shagreen-like  character. 

The  lower  jaw,  which  is  preserved  in  the  present  fossil,  likewise 
exhibits  two  characters  of  the  marine  turtles  ;  the  dentary  piece,  e.g., 
forms  a  larger  proportion  of  the  lower  jaw  than  in  land  or  fresh- 
water tortoises.  The  under  part  of  the  symphysis,  which  is  not 
larger  than  in  Chelone  My  das,  is  slightly  excavated  in  the  fossil. 

In  the  rich  collection  of  Sheppey  fossils  belonging  to  Mr.  Bower- 
bank,  there  is  a  beautiful  Chelonite,  including  the  carapace,  plastron, 
and  the  cranium,  which  is  bent  down  upon  the  forepart  of  the  plas- 
tron ;  and  which,  though  mutilated,  displays  sufficient  characters  to 
establish  its  specific  identity  with  the  skull  of  the  Chelone  breviceps 
just  described.  The  outer  surface  of  the  carapace  and  plastron  has 
the  same  finely  rugous  character  as  that  of  the  cranium,  in  which 
we  may  perhaps  perceive  a  slight  indication  of  the  affinity  with  the 
genus  Trionyx. 

The  carapace  is  long,  narrow,  ovate,  widest  in  front,  and  tapering 
towards  a  point  posteriorly ;  it  is  not  regularly  convex,  but  slopes 
away,  like  the  roof  of  a  house,  from  the  median  line,  resembling  in 
this  respect,  and  its  general  depression,  the  carapace  of  the  turtle. 
There  are  preserved  eleven  of  the  vertebral  plates,  the  two  last  alone 
being  wanting.  The  eight  pairs  of  expanded  ribs  are  also  present, 
with  sufficient  of  the  narrower  tooth-like  extremities  of  the  six  an- 
terior pairs  to  determine  the  marine  character  of  the  fossil,  which  is 
indicated  by  its  general  form.  Other  minute  characters  are  detailed ; 
and  a  comparison  with  the  Chelonite  from  the  tertiary  beds  near 
Brussels,  figured  by  Cuvier,  is  instituted. 

The  sternum  of  the  Chelone  breviceps,  although  more  ossified  than 
in  existing  Cheloniae,  yet  presents  all  the  essential  characters  of  that 
genus.  There  is  a  central  vacuity  left  between  the  hyosternals  and 
hyposternals ;  but  these  bones  differ  from  those  of  the  young  Emys 
in  the  long  pointed  processes  which  radiate  from  the  two  anterior 


372        Geological  Society:  Prof.  Owen's  Description 

angles  of  the  hyosternals,  and  the  two  posterior  angles  of  the  hy- 
posternals. 

The  xiphisternals  have  the  slender  elongated  form  and  oblique 
union  by  reciprocal  gomphosis  with  the  hyposternals,  which  is  cha- 
racteristic of  the  genus  Chelone. 

The  posterior  extremity  of  the  right  episternal  presents  the  equally 
characteristic  slender  pointed  form. 

With  these  proofs  of  the  sternum  of  the  present  fossil  being  modi- 
fied according  to  the  peculiar  type  of  the  marine  Chelones,  there  is 
evidence,  however,  that  it  differs  from  the  known  existing  species  in 
the  more  extensive  ossification  of  the  component  pieces  :  thus,  the 
pointed  rays  of  bone  extend  from  a  greater  proportion  of  the  margins 
of  the  hyo-  and  hyposternals,  and  the  intervening  margins  do  not 
present  the  straight  line  at  right  angles  to  the  radiated  processes. 

In  the  Chelone  My  das,  for  example,  one  half  of  the  external  margin 
of  the  hyo-  and  hyposternals,  where  they  are  contiguous,  are  straight, 
and  intervene  between  the  radiated  processes,  which  are  developed 
from  the  remaining  halves ;  while  in  the  Chelone  breviceps  about  a 
sixth  part  only  of  the  corresponding  external  margins  are  similarly 
free,  and  there  form  the  bottom,  not  of  an  angular,  but  a  semicircular 
interspace. 

The  radiated  processes  from  the  inner  margins  of  the  hyo-  and  hy- 
posternals are  characterized  in  the  Chelone  breviceps  by  similar  mo- 
difications, but  their  origin  is  rather  less  extensive  ;  they  terminate 
in  eight  or  nine  rays,  shorter  and  with  intervening  angles  more  equal 
than  in  existing  Chelones.  The  xiphisternal  piece  receives  in  a  notch 
the  outermost  ray  or  spine  of  the  inner  radiated  process  of  the  hy- 
posternal,  as  in  the  Chelones,  and  is  not  joined  by  a  transverse 
suture,  as  in  the  Emydes,  whether  young  or  old. 

The  characters  thus  afforded  by  the  cranium,  carapace,  plastron, 
and  some  of  the  bones  of  the  extremity,  prove  the  present  Sheppey 
fossil  to  belong  to  a  true  sea-turtle ;  and  at  the  same  time  most 
clearly  establish  its  distinction  from  the  known  existing  species  of 
Chelone  ;  from  the  shortness  of  the  skull,  especially  of  the  facial  part 
as  compared  with  its  breadth,  the  author  proposes  to  name  this  extinct 
species  Chelone  breviceps. 

2.  Chelone  longiceps. — The  second  species  of  Sheppey  turtle,  called 
Chelone  longiceps,  is  founded  upon  the  characters  of*  the  cranium,  ca- 
rapace, and  plastron.  The  cranium  differs  more  from  those  of  exist- 
ing species,  by  its  regular  tapering  into  a  prolonged  pointed  muzzle, 
than  does  that  of  the  Chelone  breviceps  by  its  short  and  truncated  jaws. 

The  surface  of  the  cranial  bones  is  smoother ;  and  their  other  mo- 
difications prove  the  marine  character  of  the  fossil  as  strongly  as  in 
the  Chelone  breviceps. 

The  orbits  are  large,  the  temporal  fossae  are  covered  principally 
by  the  posterior  frontals,  and  the  exterior  osseous  shield  completely 
overhangs  the  tympanic  and  ex-occipital  bones.  The  compressed 
spine  of  the  occiput  is  the  only  part  that  projects  further  backwards. 

The  palatal  and  nasal  regions  of  the  skull  afford  further  evidence 
of  the  affinities  of  the  present  Sheppey  Chelonite  to  the  Turtles. 


of  the  Remains  of  Marine  Turtles  from  the  Londo?i  Clay.    373 

The  bony  palate  presents  in  an  exaggerated  degree  its  great  extent 
from  the  intermaxillary  bones  to  the  posterior  nasal  aperture,  and  it 
is  not  perforated,  as  in  the  Trionyxes,  by  an  anterior  palatal  fora- 
men. 

The  extent  of  the  bony  palate  is  relatively  greater  than  in  the 
Chelone  Mydas  ;  the  trenchant  alveolar  ridge  is  less  developed  than 
in  the  Chel.  Mydas  ;  the  groove  for  the  reception  of  that  of  the  lower 
jaw  is  shallower  than  in  the  existing  Cheloniae,  or  the  extinct  Chel. 
breviceps,  arising  from  the  absence  of  the  internal  alveolar  ridge. 

The  present  species  is  distinguished  by  the  narrowness  of  the 
sphenoid  at  the  base  of  the  skull,  and  by  the  form  and  groove  of  the 
pterygoid  bones,  from  the  existing  Cheloniae,  and  <i  fortiori  from  the 
Trionyxes ;  to  which,  however,  it  approaches  in  the  elongated  and 
pointed  form  of  the  muzzle,  and  the  trenchant  character  of  the  alve- 
olar margin  of  the  jaws. 

The  general  characters  of  the  carapace  are  next  given,  and  a  spe- 
cimen from  Mr.  Bowerbank's  collection  is  more  particularly  described. 

This  carapace,  as  compared  with  that  of  the  C.  breviceps  in  the 
same  collection,  presents  the  following  differences  :  it  is  much  broader 
and  flatter ;  the  vertebral  plates  are  relatively  broader ;  the  lateral 
angle,  from  which  the  intercostal  suture  is  continued,  is  much  nearer 
the  anterior  margin  of  the  plate ;  the  C.  longiceps  in  this  respect  re- 
sembling the  existing  species  :  the  expanded  portions  of  the  ribs  are 
relatively  longer ;  they  are  slightly  concave  transversely  to  their  axis 
on  their  upper  surface,  while  in  C.  breviceps  they  are  flat.  The  ex- 
ternal surface  of  the  whole  carapace  is  smoother,  and  although  as 
depressed  as  in  most  turtles,  it  is  more  regularly  convex,  and  sloping 
away  by  two  nearly  plane  surfaces  from  the  median  longitudinal  ridge 
of  the  carapace. 

Among  the  minor  differences  of  the  two  Sheppey  fossils  the  author 
states,  that  the  first  vertebral  plate  of  C.  longiceps  is  more  convex  at 
its  middle  part,  and  sends  backwards  a  short  process  to  join  the 
second  vertebral  plate,  in  which  it  resembles  the  C.  Mydas.  The 
second  plate  is  six-sided,  the  two  posterior  lateral  short  sides  being 
attached  to  the  second  pair  of  ribs,  in  which  the  present  species  differs 
from  both  C.  Mydas  and  C.  breviceps.  The  third  vertebral  plate  is 
quadrangular  instead  of  the  second,  as  in  C.  breviceps  and  C.  Mydas. 
The  impressions  of  the  epidermal  scutes  are  deeper,  and  the  lines 
which  bound  the  sides  of  the  vertebral  scutes  meet  at  a  more  open 
angle  than  in  the  C.  breviceps,  in  which  the  vertebral  scutes  have 
the  more  regular  hexagonal  form  of  those  of  the  C.  Mydas. 

The  plastron  is  more  remarkable  than  that  of  the  C.  breviceps  for 
the  extent  of  its  ossification,  the  central  cartilaginous  space  being 
reduced  to  an  elliptical  fissure.  The  four  large  middle  pieces,  called 
hyosternals  and  hyposternals,  have  their  transverse  extent  relatively 
much  greater,  as  compared  with  their  antero-posterior  extent,  than 
in  C.  breviceps.  The  median  margins  of  the  hyosternals  are  deve- 
loped in  short  toothed  processes  along  their  anterior  two-thirds ;  and 
the  median  margins  of  the  hyposternals  have  the  same  structure 
along  their  posterior  halves. 


374-        Geological  Society :  Prof.  Owen's  Description 

The  xiphisternals  are  relatively  broader  than  in  C.  breviceps  or  in 
any  of  the  existing  species,  and  are  united  together  by  the  whole  of 
their  median  margins.  The  entosternal  piece  is  flat  on  its  under 
surface.  • 

Each  half  of  the  plastron  is  more  regularly  convex  than  in  C.  My- 
das.  The  breadth  of  the  sternum  along  the  median  suture,  uniting 
the  hyosternals  and  hyposternals,  is  five  inches ;  and  the  breadth  at 
the  junction  of  the  xiphisternals  with  the  hyposternals  is  two  inches. 

The  posterior  part  of  the  cranium  is  preserved  in  this  fossil,  with- 
drawn beneath  the  anterior  part  of  the  carapace  ;  the  fracture  shows 
the  osseous  shield  covering  the  temporal  fossae  ;  and  the  pterygoids 
remain,  exhibiting  the  wide  and  deep  groove  which  runs  along  their 
under  part. 

It  has  been  most  satisfactory,  the  author  says,  to  find  that  the  two 
distinct  species  of  the  genus  Chelone,  first  determined  by  the  skulls 
only,  should  thus  have  been  established  by  the  subsequent  observa- 
tion of  their  bony  cuirasses  ;  and  that  the  specific  differences  mani- 
fested by  the  cuirasses  should  be  proved  by  good  evidence  to  be  cha- 
racteristic of  the  two  species  founded  on  the  skulls. 

Thus  the  portion  of  the  skull  preserved  with  the  carapace  first 
described,  served  to  identify  that  fossil  with  the  more  perfect  skull 
of  the  Chelone  breviceps,  by  which  the  species  was  first  indicated. 
And,  again,  the  portion  of  the  carapace  adhering  to  the  perfect  skull 
of  the  Chelone  longiceps  equally  served  to  connect  with  it  the  nearly 
complete  osseous  buckler,  which  otherwise,  from  the  very  small  frag- 
ment of  the  skull  remaining  attached  to  it,  could  only  have  been 
assigned  conjecturally  to  the  Chel.  longiceps ;  an  approximation  which 
would  have  been  the  more  hazardous,  since  the  Chel.  breviceps  and 
Chel.  longiceps  are  not  the  only  turtles  which  swarm  those  ancient 
seas  that  received  the  enormous  argillaceous  deposits  of  which  the 
isle  of  Sheppey  forms  a  part. 

3.  Chelone  latiscutata. — A  considerable  portion  of  the  bony  cuirass 
of  a  young  turtle  from  Sheppey,  three  inches  in  length,  including 
the  2nd  to  the  7  th  vertebral  plates,  with  the  expanded  parts  of  the 
first  six  pairs  of  ribs,  and  the  hyosternal  and  hyposternal  elements 
of  the  carapace,  most  resembles  that  of  the  Chelone  coniceps  in  the 
form  of  the  carapace,  and  especially  in  the  great  transverse  extent  of 
the  above-named  parts  of  the  sternum  j  it  differs,  however,  from  the 
Chel.  longiceps  and  from  all  the  other  known  Chelonites  in  the  great 
relative  breadth  of  the  vertebral  scutes,  which  are  nearly  twice  as 
broad  as  they  are  long. 

The  central  vacuity  of  the  plastron  is  subcircular,  and,  as  might 
be  expected,  from  the  apparent  nonage  of  the  specimen,  is  wider 
than  in  the  Chel.  longiceps ;  but  the  toothed  processes  given  off  from 
the  inner  margin  of  both  hyo-  and  hyposternals  are  small,  sub- 
equal,  regular  in  their  direction,  and  thus  resemble  those  of  the 
Chel.  longiceps. 

The  length  of  the  expanded  part  of  the  third  rib  is  one  inch  seven 
lines ;  its  antero-posterior  diameter  or  breadth,  six  lines ;  in  the  form 
of  the  vertebral  extremities  of  the  ribs  and  of  the  vertebral  plates  to 


of  the  Remains  of  Marine  Turtles  from  the  London  Clay.    31 '5 

which  they  are  articulated,  the  present  fossil  resembles  the  Chel. 
longiceps. 

The  author  knows  of  no  recent  example,  however,  of  the  Chelone 
that  offers  such  varieties  in  the  form  of  its  epidermal  scutes  as  would 
warrant  the  present  Chelonite  being  considered  a  variety  merely 
of  the  Chel.  longiceps-;  and  he  therefore  indicates  the  distinct  species 
which  it  seems  to  represent,  by  its  main  distinctive  character,  under 
the  name  of  Chelone  latiscutata. 

4.  Chelone  convexa. — The  fourth  species  of  Chelone,  indicated  by 
a  nearly  complete  cuirass,  from  Sheppey,  holds  a  somewhat  inter- 
mediate position  between  the  C.  breviceps  and  C.  longiceps ;  the  ca- 
rapace being  narrower  and  more  convex  than  that  of  C.  coniceps ; 
broader,  and  with  a  concavity  arising  from  a  more  regular  curvature 
than  in  C.  breviceps.  The  expanded  parts  of  the  ribs  have  an  inter- 
mediate length  with  those  of  the  two  Chelones  with  which  this  spe- 
cimen is  compared,  and  therefore  is  a  difference  independent  of  age. 

The  distinction  of  C.  convexa  is  still  more  strikingly  established  in 
the  plastron,  which  in  its  defective  ossification  more  nearly  resembles 
that  of  the  existing  species  of  Chelone.  All  the  bones,  especially 
the  xiphisternals,  are  more  convex  on  their  outer  surface  than  in  other 
turtles,  recent  or  fossil.  The  internal  rays  of  the  hyosternals  are 
divided  into  two  groups ;  the  lower  consisting  of  two  short  and 
strong  teeth  projecting  inwards,  while  the  rest  extend  forwards  along 
the  inner  side  of  the  episternals.  The  same  character  may  be  ob- 
served in  the  corresponding  processes  of  the  hyposternals,  but  the 
external  process  is  relatively  much  narrower  than  in  C.  breviceps. 
The  following  differences  are  stated  to  distinguish  the  sternum  of 
C.  convexa  from  that  of  C.  Mydas.  The  median  margin  of  the  hyo- 
sternals forms  a  gentle  curve,  not  an  angle :  that  of  the  hyposternals 
is  likewise  curved,  but  with  a  slight  notch.  The  longitudinal  ridge 
on  the  external  surface,  and  near  the  median  margin  of  the  hyo-  and 
hyposternals,  is  less  marked  in  the  Sheppey  fossil ;  especially  in  the 
hyposternals,  which  are  characterized  by  a  smooth  concavity  in  their 
middle. 

The  suture  between  the  hyo-  and  hyposternals  is  nearer  to  the 
external  transverse  radiated  process  of  the  hyposternals.  The  me- 
dian vacuity  of  the  sternal  apparatus  is  elliptical  in  the  Chel.  con- 
vexa, but  square  in  the  Chel.  Mydas. 

The  characteristic  lanceolate  form  of  the  episternal  bone  in  the 
genus  Chelone  is  well  seen  in  the  present  fossil. 

The  true  marine  character  of  the  present  Sheppey  Chelonite  is 
likewise  satisfactorily  shown  in  the  small  relative  size  of  the  entire 
femur  which  is  preserved  on  the  left  side,  attached  by  the  matrix  to 
the  left  xiphisternal.  It  presents  the  usual  form,  a  slight  sigmoid 
flexure,  characteristic  of  the  Chelones ;  it  measures  one  inch  in 
length.  In  an  Emys  of  the  same  size,  the  femur,  besides  its  greater 
bend,  is  1^  inch  in  length. 

5 .  Chelone  subcristata. — The  fifth  species  of  Chelone  from  Sheppey, 
distinguishable  by  the  characters  of  its  carapace,  approaches  more 
nearly  to  the  Chelone  Mydas  in  the  form  of  the  vertebral  scutes, 


376         Geological  Society :  Prof.  Owen's  Description 

which  are  narrow  in  proportion  to  their  length,  than  in  any  of  the 
previously  described  species  ;  hut  is  more  conspicuously  distinct  by 
the  form  of  the  6th  and  8th  vertebral  plates,  which  support  a  short, 
sharp,  longitudinal  crest.  The  middle  and  posterior  part  of  the  first 
vertebral  plate  is  raised  into  a  convexity,  as  in  the  Chel.  longiceps, 
but  not  into  a  crest. 

The  keeled  structure  of  the  sixth  and  eighth  plates  is  more  marked 
than  in  the  fourth  and  sixth  plates  of  Chelone  Mydas,  which  are 
raised  into  a  longitudinal  ridge. 

The  characters  of  the  carapace  are  then  minutely  described. 

Sufficient  of  the  sternum  is  exposed  in  the  present  fossil  to  show, 
by  its  narrow  elongated  xiphisternals,  and  the  wide  and  deep  notch 
in  the  outer  margin  of  the  conjoined  hyo-  and  hyposternals,  that  it 
belongs  to  the  marine  Chelones. 

The  xiphisternals  are  articulated  to  the  hyposternals  by  the  usual 
notch  or  gomphosis ;  they  are  straighter  and  more  approximated 
than  in  the  Chel.  Mydas ;  the  external  emargination  of  the  plastron 
differs  from  that  of  the  Chel.  Mydas  in  being  semicircular  instead 
of  angular,  the  Chel.  subcristata  approaching,  in  this  respect,  to  the 
Chel.  breviceps. 

The  shortest  antero-posterior  diameter  of  the  conjoined  hyo-  and 
hyposternals  is  two  inches  seven  lines.  The  length  of  the  xiphi- 
sternal two  inches  six  lines.  The  breadth  of  both,  across  their 
middle  part,  one  inch  three  lines. 

The  name  proposed  for  this  species  indicates  its  chief  distinguish- 
ing character,  viz.  the  median  interrupted  carina  of  the  carapace, 
which  may  be  presumed  to  have  been  more  conspicuous  in  the  horny 
plates  of  the  living  animal  than  in  the  supporting  bones  of  the  fos- 
silized carapace. 

6.  Chelone  planimentum. — This  species  is  founded  on  an  almost 
entire  specimen  of  skull  and  carapace  of  the  same  individual,  in  the 
museum  of  Prof.  Sedgwick;  on  a  skull  and  carapace  belonging  to 
different  individuals,  in  the  museum  of  Prof.  Bell ;  and  on  a  carapace 
in  the  British  Museum ;  all  of  which  specimens  are  from  the  London 
clay  at  Harwich. 

The  skull  resembles,  in  the  pointed  form  of  the  muzzle,  the  Chel. 
longiceps  of  Sheppey,  but  differs  in  the  greater  convexity  and  breadth 
of  the  cranium,  and  the  great  declivity  of  its  anterior  contour. 

The  great  expansion  of  the  osseous  roof  of  the  temporal  fossae,  and 
the  share  contributed  to  that  roof  by  the.  post-frontals,  distinguish 
the  present,  equally  with  the  foregoing  Chelonites,  from  the  fresh- 
water genera  Emys  and  Trionyx.  In  the  oblique  position  of  the 
orbits,  and  the  diminished  breadth  of  the  interorbital  space,  the  pre- 
sent Chelonite,  however,  approaches  nearer  to  Trionyx  and  Emys  than 
the  previously  described  species. 

Its  most  marked  and  characteristic  difference  from  all  existing  or 
extinct  Chelones  is  shown  by  the  greater  antero-posterior  extent  and 
flatness  of  the  under  part  of  the  symphysis  of  the  lower  jaw,  whence 
the  specific  name  here  given  to  the  species. 

Since  at  present  there  is  no  means  of  identifying  the  well-marked 


of  the  Remains  of  Marine  Turtles  from  the  London  Clay.     377 

species  of  which  the  skull  is  here  described  with  the  Chelonite  figured 
in  the  frontispiece  to  Woodward's  '  Synoptical  Table  of  British 
Organic  Remains,'  and  alluded  to  without  additional  description  or 
characters  as  the  '  Chelonia  Harvicensis '  in  the  additions  to  Mr. 
Gray's  'Synopsis  Reptilium,'  p.  78,  1831;  and  since  it  is  highly 
probable  that  the  extensive  deposit  of  Eocene  clay  along  the  coast  of 
Essex,  like  that  at  the  mouth  of  the  Thames,  may  contain  the  relics 
of  more  than  one  species  of  our  ancient  British  turtles,  the  author 
prefers  indicating  the  species  here  described  by  a  name  having  refer- 
ence to  its  peculiarly  distinguishing  character,  to  arbitrarily  associa- 
ting the  skull  with  any  carapace  to  which  the  vague  name  of  Harvi- 
censis has  been  applied. 

Besides  the  specimen  of  Chelonite  from  Harwich,  in  the  museum 
of  Norwich,  figured  by  Woodward,  there  is  a  mutilated  carapace  of 
a  young  Chelone  from  the  same  locality  in  the  British  Museum. 
This  specimen  exhibits  the  inner  side  of  the  carapace,  with  the  heads 
and  part  of  the  expanded  bodies  of  four  pairs  of  ribs.  It  is  not  suf- 
ficiently entire  to  yield  good  specific  characters,  but  it  demonstrates 
unequivocally  its  title  to  rank  with  the  marine  turtles.  It  is  figured 
in  Mr.  Kcenig's  '  Icones  Sectiles,'  pi.  xvi.  fig.  192,  under  the  name 
of  Testudo  plana. 

The  carapace  of  a  larger  specimen  of  Chelone,  from  the  coast  of 
Harwich,  was  purchased,  by  the  British  Museum,  of  Mr.  Charles- 
worth,  by  whom  a  lithograph  of  the  inner  surface  of  this  Chelonite,  of 
the  natural  size,  has  been  privately  distributed,  without  description. 

The  carapace  in  the  museum  of  Prof.  Sedgwick,  forming  part  of 
the  same  individual  (Chelone  planimentum)  as  the  skull  above  described, 
exhibits  many  points  of  anatomical  structure  more  clearly  than  the 
last-mentioned  Chelonite  in  the  British  Museum  ;  it  also  displays  the 
characteristic  coracoid  bone  of  the  right  side  in  its  natural  relative 
position.  The  resemblance  of  this  carapace  in  general  form  to  that 
of  the  Chelone  caretta  is  pretty  close ;  it  differs  from  that  and  other 
known  existing  turtles,  and  likewise  from  most  of  the  fossil  species, 
in  the  thickness  and  prominence  of  the  true  costal  portions  of  the 
expanded  vertebral  ribs,  which  stand  out  from  the  under  surface  of 
the  plate  through  their  entire  length,  and  present  a  somewhat  angular 
obtuse  ridge  towards  the  cavity  of  the  abdomen. 

In  the  large  proportional  size  of  the  head,  the  Chelone  planimentum 
corresponds  with  the  existing  turtles ;  and  that  the  extinct  species 
here  described  attained  larger  dimensions  than  those  given  above,  is 
proved  by  a  fossil  skull  from  the  Harwich  clay,  in  the  collection  of 
Prof.  Bell,  which  exhibits  well  the  character  of  the  broad  and  flattened 
symphysis. 

A  carapace  of  a  smaller  individual  of  Chelone  planimentum  from  the 
Harwich  coast,  with  the  character  of  the  inwardly  projecting  ribs 
strongly  marked,  is  likewise  preserved  in  the  choice  collection  of  the 
same  excellent  naturalist.  One  of  the  hyosternal  bones  enclosed  in 
the  same  nodule  of  clay  testifies  to  the  partial  ossification  of  the 
plastron  in  this  species. 

In  the  summary  of  the  foregoing  details  the  author  observes,  that 
Phil.  Mag.  S.  3.  Vol.  21 .  No.  1 39.  Nov.  1842.  2  C 


378  Chemical  Society. 

they  lead  to  conclusions  of  much  greater  interest  than  the  previous 
opinions  respecting  the  Chelonites  of  the  London  basin  could  have 
originated.  Whilst  these  were  supposed  to  have  belonged  to  a  fresh- 
water genus,  the  difference  between  the  present  fauna  and  that  of 
the  Eocene  period,  in  reference  to  the  Chelonian  order,  was  not  very 
great ;  since  the  Emys  or  Cistudo  Europaa  still  abounds  on  the  Con- 
tinent, and  lives  long  in  our  own  island  in  suitable  localities :  but 
the  case  assumes  a  very  different  aspect  when  we  come  to  the  con- 
viction, that  the  majority  of  the  Sheppey  Chelonites  belong  to  the 
true  marine  genus  Chelone ;  and  that  the  number  of  species  of  the 
Eocene  extinct  turtles  already  obtained  from  so  limited  a  space  as 
the  isle  of  Sheppey  exceeds  that  of  the  species  of  existing  Chelone. 

Notwithstanding  the  assiduous  search  of  naturalists,  and  the  attrac- 
tions to  the  commercial  voyager  which  the  shell  and  the  flesh  of  the 
turtles  offer,  all  the  tropical  seas  of  the  world  have  hitherto  yielded 
no  more  than  five  well-defined  species  of  Chelone,  and  of  these  only 
two,  as  the  C.  Mydas  and  C.  caretta,  are  known  to  frequent  the  same 
locality. 

It  is  obvious,  therefore,  that  the  ancient  ocean  of  the  Eocene  epoch 
was  less  sparingly  inhabited  by  turtles ;  and  that  these  presented  a 
greater  variety  of  specific  modifications  than  are  known  in  the  seas 
of  the  warmer  latitudes  of  the  present  day. 

The  indications  which  the  Sheppey  turtles  afford  of  the  warmer 
climate  of  the  latitude  in  which  they  lived,  as  compared  with  that 
which  prevails  there  in  the  present  day,  accord  with  those  which  all 
the  organic  remains  of  the  same  depositary  have  hitherto  yielded  in 
reference  to  this  interesting  point. 

That  abundance  of  food  must  have  been  produced  under  such  in- 
fluences cannot,  Mr.  Owen  states,  be  doubted ;  and  he  infers,  that  to 
some  of  the  extinct  species — which,  like  the  C.  coniceps  and  C.platy- 
gnathus,  exhibit  either  a  form  of  head  well  adapted  for  penetrating 
the  soil,  or  with  modifications  that  indicate  an  affinity  to  the  Trio- 
nyxes — was  assigned  the  task  of  checking  the  undue  increase  of  the 
extinct  crocodiles  of  the  same  epoch  and  locality,  by  devouring  their 
eggs  or  their  young,  becoming  probably,  in  return,  themselves  an  oc- 
casional prey  to  the  older  individuals  of  the  same  carnivorous  saurian. 


CHEMICAL  SOCIETY. 
[Continued  from  p.  320.] 
March  15,  1842. — The  following  communications  were  read : — 
Second  Part  of  Mr.  Hutchinson's  Paper.     (See  p.  3 1 8.) 
"On  the  Preparation  of  artificial  Yeast,"  by  George  Fownes,  Ph.D. 
This  paper  appears  in  the  present  Number,  p.  352. 

March  30. — Anniversary  Meeting,  Thomas  Graham,  Esq.,  F.R.S., 
Professor  of  Chemistry  in  University  College,  London,  President,  in 
the  Chair. 

The  Report  of  the  Council  on  the  state  and  prospects  of  the  So- 
ciety was  read,  and  the  following  gentlemen  were  elected  as  Officers 
and  Council  for  the  ensuing  year  : — 


Dr.  Schweitzer's  Analysis  of  the  Chalk  of  Brighton.    379 

President. — Thos.  Graham,  Esq.  Vice-Presidents. — William  Thos. 
Brande,  Esq. ;  John  Thos.  Cooper,  Esq. ;  Michael  Faraday,  Esq., 
D.C.L. ;  Richard  Phillips,  Esq.  Treasurer. — Arthur  Aikin,  Esq. 
Secretaries. — Robert  Warington  and  George  Fownes;  Foreign  Secre- 
tary.— E.  F.  Teschemacher.  Council. — Dr.  Thos.  Clark ;  Dr.  Chas. 
Daubeny ;  John  Fred.  Daniell,  Esq. ;  Thos.  Everitt,  Esq. ;  W.  R. 
Grove,  Esq. ;  James  F.  W.  Johnston,  Esq. ;  Percival  N.  Johnson, 
Esq. ;  George  Lowe,  Esq. ;  ^William  H.  Miller,  Esq. ;  Robert  Por- 
rett,  Esq. ;  Dr.  G.  O.  Rees  ;  Lieut.-Colonel  Philip  Yorke. 

The  laws  of  the  Society,  as  drawn  up  by  the  Council,  were  sub- 
mitted to  the  meeting,  and  having  been  read  and  discussed,  were 
confirmed,  with  amendments,  and  ordered  to  be  printed  for  the  use 
of  the  members. 

April  5. — The  following  communications  were  read : — 

Extract  from  a  letter  from  Wm.  H.  Miller,  Esq.,  Professor  of  Mi- 
neralogy in  the  University  of  Cambridge. 

"  I  regret  that  my  engagements  in  Cambridge  have  prevented  my 
being  present  at  the  meeting  of  the  Chemical  Society,  especially  as 
I  was  desirous  of  offering  my  services  in  determining  the  form  of  any 
crystalline  products  that  may  present  themselves  to  chemists  who 
are  engaged  in  original  researches.  Also,  in  return,  I  might  make 
bold  to  ask  some  members  of  the  Society  to  supply  me  with  certain 
objects  of  crystallographic  and  optical  research  from  their  laborato- 
ries." 

"  On  the  Analysis  of  the  Chalk  of  the  Brighton  Cliffs,"  by  Dr. 
Edw.  G.  Schweitzer. 

My  attention  was  directed  to  the  soil  of  this  neighbourhood,  for 
the  purpose  of  ascertaining  if  the  chalk  contains  any  ingredient  pe- 
culiarly favourable  to  the  growth  of  Gramineae,  in  consequence  of 
the  well-known  fact,  that  the  herbage  of  the  South  Downs,  along 
the  coast  of  Sussex,  affords  a  superior  food  for  cattle,  producing  meat 
of  excellent  quality,  for  which  these  Downs  are  justly  celebrated. 
The  result  of  my  analysis  substantiates  the  presence  of  phosphate  of 
lime,  an  ingredient  valuable  for  the  nutrition  of  plants.  The  chalk 
is  composed  of  the  following  substances  in  100  parts: — 


98-57 

of  magnesia  .... 

0-38 
Oil 
0-08 

006 
016 

Silica 

0*64 

10000 

To  ascertain  the  quantity  of,  phosphoric  acid,  I  followed  Dr. 
Schulze's  method  (Journal  fiir  prakt.  Chemie,  xxi.  S.  387-389), 
which  he  recommends  for  the  analytical  investigation  of  soils. 
Finding  it  useful  and  correct,  I  subjoin  an  extract  from  his  treatise. 
The  process  is  based  upon  the  fact,  that  phosphate  of  lime  and 
phosphate  of  magnesia  are  soluble  in  acetic  acid,  while  the  phos- 
phate of  peroxide  of  iron  and  phosphate  of  alumina  are  not  so. 

2C2 


380  Chemical  Society :  Mr.  Parnell  on  the 

This  being  the  case,  the  soil  or  mineral  is  to  be  treated  with  hydro- 
chloric acid,  and  the  iron  which  the  solution  contains  per-oxidised, 
the  phosphate  of  protoxide  of  iron  being  soluble  in  acetic  acid. 
Should  the  muriatic  solution  contain  more  phosphoric  acid  than 
oxide  of  iron  or  alumina,  (which  seldom  is  the  case,  as  the  latter  are 
usually  predominant,)  peroxide  of  irc.^.  or  alumina  is  to  be  added, 
the  solution  must  also  be  freed  from  every  trace  of  silica.  The 
earthy  muriates  are  precipitated  with  ammonia,  after  which  acetic 
acid  is  added,  and  the  whole  gently  digested.  The  precipitate  will 
dissolve  again,  with  the  exception  of  the  phosphates  of  peroxide  of 
iron  and  alumina.  When  both  these  ingredients  enter  into  the  pre- 
cipitate, caustic  potassa  will  give  the  means  of  ascertaining  their 
respective  quantities. 

The  solubility  of  the  phosphate  of  protoxide  of  iron,  and  the  inso- 
lubility of  the  phosphate  of  peroxide  of  iron  in  acetic  acid,  when 
freshly  precipitated,  give  an  excellent  method  to  separate  quantita- 
tively these  two  degrees  of  oxidation.    The  manipulation  is  obvious. 

The  discovery  by  Professor  Ehrenberg,  that  the  Brighton  chalk 
consists  of  microscopic  shells,  is  a  decided  proof  of  its  animal  origin, 
to  which  may  now  be  added  an  additional  one,  viz.  the  presence  of 
phosphate  of  lime,  which  is  a  usual,  although  secondary  ingredient 
of  the  shells  of  Crustacea?. 

"  On  the  Action  of  Chromate  of  Potash  on  the  Protosulphate  of 
Manganese,"  by  Robert  Warington,  Esq.     See  Chem.  Soc. 

In  the  course  of  some  experiments  on  the  formation  of  double 
salts  of  chromic  acid  with  various  bases  depending  on  the  tendency 
which  might  arise,  from  the  resulting  affinities,  to  the  formation  of 
certain  crystallized  combinations,  the  subject  of  the  present  brief 
communication  came  under  my  notice. 

On  adding  a  solution  of  the  yellow  chromate  of  potash  to  one  of 
the  protosulphate  of  manganese,  no  turbidity  or  precipitate  takes 
place,  but  the  mixed  fluids  become  of  a  deep  orange  red  colour,  and 
after  a  short  period  the  surface  is  covered  with  a  dark  brown  crust 
or  film,  and  the  whole  of  the  containing  vessel  is  coated  with  the 
same  substance ;  at  times  when  the  solutions  are  dilute,  this  deposit 
assumes  a  crystalline  appearance.  If  this  compound  is  prepared 
under  the  microscope,  in  the  manner  described  in  a  former  paper, 
the  first  effect  is  the  appearance  of  numerous  minute  spherical  gra- 
nules of  a  fine  crimson  brown  colour,  which  gradually  increase  in 
size  until  about  from  six  to  seven  250ths  or  '025  of  an  inch  in  dia- 
meter ;  a  number  of  delicate  crystallized  spiculse  are  then  observed 
to  start  out  in  radii  from  their  sides  ;  and  when  the  solutions  em- 
ployed for  its  production  are  diluted,  fine  stellated  groups  of  pris- 
matic crystals  are  obtained.  When  this  substance,  which  has  a 
dark  chocolate  hue,  is  examined  by  a  strong  transmitted  light,  it 
has  a  rich  crimson  brown  colour  :  it  possesses  the  following  proper- 
ties : — it  is  soluble  in  diluted  nitric  or  sulphuric  acids,  without 
residue,  yielding  an  orange-coloured  solution ;  when  acted  upon  by 
hydrochloric  acid  chlorine  is  evolved,  and  a  brown  fluid  results, 
which  by  the  addition  of  a  few  drops  of  alcohol  or  other  deoxidizing 


Equilibrium  of  Temperature  of  Bodies  in  Contact.     381 

agent,  becomes  of  a  fine  emerald  green.  The  following  analysis  was 
made  of  it : — 8*2  grains,  previously  dried  at  a  temperature  of  boiling 
water,  were  submitted  to  a  long-continued  red  heat  in  a  small  green 
glass  tube,  to  which  a  chloride  of  calcium  tube  was  attached;  it 
lost  1*0  grain,  which  corresponded  with  the  weight  gained  by  the 
absorption  tube ;  8*2  grains  dissolved  in  dilute  nitric  acid,  and  pre- 
cipitated while  boiling  by  caustic  potash,  gave,  after  the  necessary 
treatment,  4*5  grains  of  the  red  oxide  of  manganese ;  the  solution 
was  then  acidified  by  sulphuric  acid,  and  evaporated  to  dryness  to 
expel  the  nitric  acid,  redissolved,  deoxidized  by  alcohol  and  the 
oxide  of  chromium  thrown  down  by  ammonia,  again  evaporated  to 
dryness,  to  avoid  the  possibility  of  any  of  the  oxide  being  in  solu- 
tion, and  the  oxide  of  chromium,  well  washed,  gave  2*3  grains.  We 
have  therefore 

4*5  grains  red  oxide  manganese. .   =4*188  protoxide 
2*3     ...     protoxide  chromium  . .  =  3*000  chromic  acid 
1*0     ...     water 1*000  water 

8*188 

By  calculation  this  should  be  . .      4*141  protoxide 

3*014  chromic  acid 
1*043  water 

Or,  1  atom  chromic  acid  -f  2  atoms  protoxide  of  manganese  +  2 
atoms  water.     Represented  by  Cr  03  +  2  Mn  O  .  +  2  H .  O 

April  19. — The  following  communications  were  read  : — 

"  On  the  Equilibrium  of  the  Temperature  of  Bodies  in  contact," 
by  E.  A.  Parnell,  Esq. 

In  reference  to  observations  recently  made  by  Mr.  Hutchinson  on 
the  difficulty  of  raising  the  temperature  of  any  substance  to  the  de- 
gree of  the  medium  by  which  the  heat  is  applied*,  Mr.  Parnell  ob- 
serves, "  From  what  I  know  of  the  mode  in  which  Mr.  Hutchinson 
operated,  it  is  probable  that  a  loss  of  heat  occurred  by  radiation  from 
the  substance  operated  on ;  by  radiation,  first  to  the  cover  of  the 
bath,  and  from  this  to  external  objects.  On  adopting  precautions 
to  avoid  this  source  of  error,  I  found  that  in  a  steam-bath  the  tem- 
peratures attained  by  substances,  were 

1.  Olive  oil &  degree  below  the  temperature  of  the  steam. 

2.  Water § 

And  in  a  water-bath, — 

3.  Water ^  degree  below  the  temperature  of  the  water. 

4.  Vapour  of  aether  1  ...  ...  ... 

5.  Air 1 

In  the  two  first  experiments,  the  apparatus  used  was  a  large  flask, 
closed  with  a  cork,  having  several  perforations,  through  one  of  which 
was  admitted  a  wide  tube  containing  the  liquid  operated  on,  the 
tube  not  dipping  so  far  as  the  surface  of  the  water  in  the  flask,  which 
was  kept  boiling. 

In  the  remaining  three  a  copper  water-bath  was  employed,  the 

[*  An  abstract  of  Mr.  Hutchinson's  paper  will  be  found  at  p.  318.] 


S82  Chemical  Society, 

water,  vapour  or  air  being  contained  in  a  glass  globe  of  about  fif- 
teen cubic  inches  capacity,  having  a  narrow  neck,  through  which 
the  thermometer  was  admitted.  The  globe  was  supported  in  the 
bath  by  a  wire -cage  in  the  same  manner  as  is  done  in  the  operation 
of  taking  the  density  of  vapours. 

It  would  hence  appear  from  the  proximity  of  the  temperature  of 
the  substance  heated  and  the  bath,  that  if  the  experiments  were  con- 
tinued a  sufficient  length  of  time,  and  every  chance  of  error  avoided, 
the  substance  might  be  heated  to  an  equal  degree,  and  the  law  of 
equilibrium  of  temperature  maintain  its  universality. 

I  could  never,  however,  raise  the  temperature  of  aether  vapour 
nearer  than  one  degree  below  the  temperature  of  the  bath,  and  to 
effect  this  required  at  least  half  an  hour.  I  would  therefore  recom- 
mend, in  taking  the  density  of  vapours,  that  the  temperature  of  the 
globe  be  considered  as  one  degree  less  than  that  of  the  bath,  in 
making  the  calculations.  Notwithstanding,  with  this  correction 
the  weight  of  the  vapour  can  scarcely  be  effected  to  a  greater  extent 
than  '04  grain. 

"  On  the  Preparation  of  Hippuric  Acid,"  by  Geo.  Fownes,  Esq.* 

Being  very  desirous  of  possessing  a  specimen  of  a  very  interesting 
substance,  hippuric  acid,  namely,  and  failing  to  obtain  it  in  any 
quantity  from  the  horse-urine  collected  in  London  stables,  I  was 
induced  to  make  trial  of  that  of  cows,  and  speedily  found  it  to  be  a 
substance  highly  advantageous  for  the  purpose. 

Perfectly  fresh  cow-urine  presents  the  aspect  of  a  transparent 
amber-coloured  liquid  of  peculiar  but  not  disagreeable  odour,  and 
quite  neutral  to  test-paper.  When  this  is  evaporated  down  in  a 
water-bath  to  about  one-tenth,  and  mixed  with  hydrochloric  acid,  a 
very  large  quantity  of  a  brown  crystalline  substance  separates, 
which  is  hippuric  acid.  It  is  very  easy  in  this  way  to  operate  upon 
whole  gallons  of  the  liquid,  and  thus  procure  many  ounces  of  hip- 
puric acid. 

To  purify  this  substance,  I  find  the  following  method  very  ad- 
vantageous. The  brown  rough  acid  is  dissolved  in  boiling  water, 
of  which,  by  the  way,  it  requires  a  much  larger  quantity  than  from 
the  descriptions  given  would  be  imagined,  and  through  the  solution 
a  stream  of  chlorine  gas  is  transmitted,  until  the  odour  of  that  gas 
becomes  perceptible  in  the  liquid,  and  its  brown  colour  passes  into 
a  sort  of  deep  amber-yellow.  The  hot  solution  is  then  filtered 
through  cloth,  and  upon  cooling,  the  acid,  still  very  impure,  crystal- 
lizes out.  The  acid  is  next  dissolved  in  a  dilute  hot  solution  of 
carbonate  of  soda,  taking  care  to  have  a  little  excess  of  the  alkali, 
digested  for  a  few  minutes  with  a  little  animal  charcoal,  filtered,  and 
lastly,  the  solution  strongly  acidified  by  hydrochloric  acid,  which 
removes  the  base  and  sets  free  the  hippuric  acid.  Should  that 
substance  not  be  by  such  treatment  rendered  perfectly  white,  it 

[*  A  paper  on  the  conversion  of  benzoic  into  hippuric  acid,  by  Mr. 
Garrod,  read  before  the  Chemical  Society,  January  18,  will  be  found  in 
Phil.  Mag.,  S.  3.  vol.  xx.  p.  501.] 


Mr.  Fownes  on  the  Preparation  of  Hippuric  Acid.    383 

may  be  again  dissolved  in  hot  water,  a  little  chlorine  passed,  the 
solution  supersaturated  with  carbonate  of  soda,  digested  with  animal 
charcoal,  and  once  more  decomposed  by  an  acid. 

It  is  to  be  observed,  that  hippuric  acid  only  crystallizes  in  a 
distinct  and  characteristic  manner  when  pure,  or  at  least  when  in 
a  condition  approaching  that  state ;  under  other  circumstances  it 
usually  separates  either  as  short  radiated  needles,  or  as  a  granular 
crystalline  powder.  The  latter  happens  when  soluble  salt  is 
present. 

If  the  urine,  instead  of  being  quite  fresh,  is  at  all  ammoniacal, 
then  during  the  evaporation  a  very  large  quantity  of  ammonia  is 
disengaged,  accompanied  by  slow  effervescence,  and  the  liquid 
affords,  as  Liebig  has  already  pointed  out,  benzoic  acid  only,  with- 
out a  trace  of  hippuric. 

The  great  density  of  the  urine  of  the  cow  is  a  remarkable  circum- 
stance ;  one  sample,  affording  much  hippuric  acid,  gave  the  sp.  gr. 
of  1*0325,  which  is  considerably  higher  than  that  of  human  urine. 
This  density  is  chiefly  due  to  a  most  prodigious  quantity  of  urea, 
which  is  easily  extracted  from  the  brown  liquid  remaining  after  the 
separation  of  the  hippuric  acid,  by  the  aid  of  a  hot  strong  solution  of 
oxalic  acid,  which  throws  down  the  slightly  soluble  oxalate.  This 
can  be  decomposed  by  chalk,  and  the  urea  extracted  without  ha- 
ving recourse  to  alcohol.  Besides  these  two  substances,  hippuric 
acid,  or  rather  hippurate  of  an  alkali,  and  urea,  cow-urine  contains 
a  little  uric  acid,  phosphates  and  other  salts  in  tolerable  abun- 
dance. 

The  constant  occurrence  of  so  much  urea  in  the  urine  of  all  ani- 
mals, both  granivorous  and  flesh- eating,  tends  greatly  to  strengthen 
the  opinion,  that  it  is  by  this  channel  almost  alone  that  the  removal 
of  those  portions  of  the  azotized  constituents  of  the  body,  which 
have  been  worn  out,  as  it  were,  or  in  the  act  of  undergoing  decay,  is 
effected.  It  is  well  known  that  such  substances,  by  ordinary  putre- 
faction, furnish  carbonate  of  ammonia ;  but  in  the  body  this  process 
seems  to  have  been  modified  in  such  a  manner,  that  in  place  of  that 
substance,  urea  or  carbamide  is  generated,  which  is  destitute  of  the 
irritating  power  upon  the  organs  which  a  corresponding  quantity  of 
the  ammoniacal  salt  would  possess. 

It  has  been  suggested  that  hippuric  acid  is  not  a  direct  product 
of  the  animal  system,  but  is  formed  by  the  union  of  benzoic  acid  or 
its  elements  with  those  of  lactate  of  urea,  the  benzoic  acid  being 
present  in  the  food,  and  the  recent  experiments  of  Mr.  Garrod  cer- 
tainly countenance  the  opinion.  But  these  attempts  to  detect  ben- 
zoic acid  in  the  food  of  these  animals  were  in  the  hands  of  Liebig 
quite  unsuccessful,  and  it  seems  unlikely  that  it  would  be  found  at 
any  rate  in  considerable  quantity  in  such  substances  as  grains  and 
mangel-wurzel,  which,  with  the  addition  of  a  little  hay,  consti- 
tuted the  food  of  the  cows  from  which  such  an  abundant  supply  of 
hippuric  acid  was  obtained. 

There  is  only  one  other  point  which  requires  notice,  and  that  is 
1  the  nature  of  the  change  which  hippuric  acid  so  readily  undergoes 


384  Chemical  Society. 

by  putrefaction.  It  is  astonishing  that  a  substance  which  so  pow- 
erfully resists  the  action  of  chlorine,  should  be  so  easily  affected  by 
simple  contact  with  putrefying  matter. 

A  glance  at  the  composition  of  hippuric  acid  will  show  that  this 
change  is  altogether  different  from  that  which  urea  suffers  under 
similar  circumstances,  the  assimilation,  namely,  of  the  elements  of 
water  by  which  it  becomes  carbonate  of  ammonia.  Hippuric  acid, 
on  the  contrary,  seems  to  pass  into  benzoic  by  an  absorption  of 
oxygen  from  the  air,  carbonic  acid  and  ammonia  being  at  the  same 
time  produced. 

Hippuric  acid  ....     C18  H8  N  05 
Subtract — Benzoic  acid CH  H5      03 

C4    H3  N  Os 

which  by  addition  of  6  eq.  of  oxygen  from  the  air,  would  furnish 
1  eq.  ammonia  and  4  eq.  carbonic  acid. 

May  3. — The  following  communication  was  made  : — 

"On  a  curious  Formation  of  Prussian  Blue,"  by  Robert  Por- 
rett,  Esq. 

Mr.  Porrett  was  led  to  attend  to  this  subject  by  an  observation 
accidentally  made  while  walking  in  the  garden  of  a  friend.  He 
found  that  a  great  number  of  the  pebbles  in  the  gravel  walk  were 
tinged  of  a  fine  bright  blue  colour ;  and  on  remarking  the  appear- 
ance to  the  owner,  and  inquiring  as  to  the  cause,  though  it  had 
never  before  attracted  notice,  he  ascertained  that  before  the  fresh 
gravel  had  been  laid  down,  the  walks  had  been  strewed  with  some 
refuse  lime  from  the  gas-works,  for  the  purpose  of  destroying  the 
worms,  and  over  which  the  red  gravel  of  the  neighbourhood  of 
London  had  been  placed  only  a  few  weeks  before  the  appearances 
described  were  observed. 

The  blue  colour  was  entirely  confined  to  the  upper  surface  of  the 
pebbles  which  was  exposed  to  the  atmospheric  air,  and  was  found  to 
be  Prussian  blue.  The  pebbles  affected  were  siliceous,  having  a 
white  exterior  coating.  Mr.  Porrett  considers  this  production  of 
Prussian  blue  to  have  arisen  from  some  of  the  gas-lime  having  been 
'  dropped  accidentally  on  the  surface  of  the  new  gravel,  and  that  the 
peroxide  of  iron  there  found  had  been  deoxidized  by  some  of  the 
sulphur  compounds  contained  in  the  gas-kme,  giving  rise  to  the 
formation  of  a  combination  of  iron  with  cyanogen,  also  present  in 
the  Ume,  and  calcium,  and  that  this  compound  had  been  decomposed 
by  the  action  of  the  carbonic  acid  of  the  atmosphere,  or  by  the 
siliceous  matter  of  the  stone,  and  thus  causing  the  formation  of  the 
Prussian  blue*. 

May  17. — The  following  communications  were  read : — 

Extract  from  a  letter  from  Professor  Clark. 

"  The  burner  is  to  be  fixed  into  a  table  by  screwing  thereto  the  cir- 

[*  On  a  subject  allied  to  that  of  Mr.  Porrett's  paper,  see  Phil.  Mag., 
S.  3.  vol.  x.  p.  329,  and  also  the  notice  referred  to,  p.  333.] 


Professor  Clark's  Gas  Burner. 


385 


I 


cular  projection//".  There  are  two  stop-cocks.  The 
horizontal  one  g  is  for  admitting  the  supply  of  gas, 
which  passes  up  the  fixed  tubepp  into  the  sliding  tube 
m  m.  Between  the  outer  fixed  tube  1 1  and  the  inner 
fixed  tube  p  p,  water  is  contained  to  serve  as  a  lute  to 
confine  the  gas.  The  sliding  tube  is  kept  at  whatever 
height  it  may  be  placed,  by  means  of  a  spring  inserted 
in  a  stuffing-box  formed  by  the  screws 5  above ff. 
The  spring  is  represented  apart,  r.  It  is  formed  out 
of  a  short  bit  of  another  metallic  tube  of  such  bore  as 
only  to  permit  the  tube  mm  to  slide  through  it  easily. 
Four  holes  in  the  circle  of  the  wider  tube  r  are  bored 
at  equal  distances,  and  a  vertical  slit  is  cut  by  a  saw 
from  each  hole  through  to  the  bottom  of  the  tube. 
After  being  thus  cut,  the  cut  parts  are  squeezed  to- 
gether by  the  hand,  and  the  tube  r  being  put  over 
the  tube  m  and  confined  in  the  stuffing-box  at  s,  forms 
a  convenient  spring  for  keeping  the  sliding  tube  m  at 
whatever  height  it  may  be  placed.  The  stop-cock  w 
is  to  let  out  any  water  that  may  by  accident  get  into 
the  tube  pp.  The  tube  mm  should  not  be  less  than 
half  an  inch  in  diameter.  The  burner  b,  which  is 
copied  after  one  inProfessor  Graham's  laboratory,  Uni- 
versity College,  burns  after  the  manner  of  a  rose- 
burner,  but  it  is  in  the  form  of  a  ring,  instead  of 
being  solid.  It  may  be  called  a  ring-burner.  It  per- 
mits a  much  more  free  access  of  air,  especially  when 
the  flame  is  placed  very  close  to  a  vessel.  This  burner 
also  supplies  gas  very  advantageously  for  mixture  with 
air  in  a  cylinder,  at  the  top  of  which  the  mixture 
burns  over  wire  gauze.   The  sliding  tube  relieves  the       \l  |J  8 

operator  from  all  cumbrous  supports  to  his  burner,  or 
from  the  necessity  of  having  moveable  supports  to 
the  vessels  to  be  heated.  A  ring  supported  by  three 
legs,  the  whole  made  of  tinned  iron,  affords  a  cheap, 
stable  and  convenient  support  to  vessels,  although  of 
considerable  weight." 

"  On  some  Salts  of  Cadmium,"  by  Henry  Croft, 
Esq.  This  paper  is  inserted  in  the  present  Number 
of  the  Philosophical  Magazine,  p.  355. 

"  An  Examination  of  two  specimens  of  South  Sea  Guano,  im- 
ported for  agricultural  use,"  by  George  Fownes,  Esq. 

No  1. — Presented  the  aspect  of  a  pale-brown  soft  powder,  with 
a  few  lumps,  having  in  their  inside  whitish  specks  ;  its  odour  was 
exceedingly  offensive. 

Treated  with  hot  water  and  filtered,  it  gave  a  yellow,  feebly  alka- 
line solution,  not  rendered  turbid  to  any  extent  by  the  addition  of 
acid,  which  contained  much  ammoniacal  salt,  some  sulphate  and 
chloride,  a  very  large  quantity  of  oxalate,  and  both  potash  and  soda, 
the  latter  most  abundant. 


386  Chemical  Society, 

The  undissolved  substance  appeared  to  be  a  mixture  of  uric  acid, 
earthy  phosphates,  and  brown  organic  matter. 

Fifty  grains  of  guano  by  incineration  in  a  platinum  vessel  left  16*9 
grs.  fine  greyish  white-ash.  This  ash,  treated  with  hot  water,  and 
the  whole  placed  on  a  filter,  left  a  quantity  of  insoluble  matter, 
weighing,  after  being  well  washed,  dried  and  ignited,  14*6  grs. : 
this  was  almost  entirely  soluble  in  warm  dilute  hydrochloric  acid, 
precipitated  by  the  addition  of  ammonia,  and  evidently  consisted  of 
phosphates  of  lime  and  magnesia. 

The  aqueous  solution  was  slightly  alkaline,  contained  much  chlo- 
ride, some  sulphate,  a  very  notable  quantity  of  soluble  phosphate, 
some  potash,  and  a  good  deal  of  soda. 

Hence  the  following  approximate  result  :< — 
Oxalate  of  ammonia  with  trace  of  carbonate, 

undecomposed  uric  acid,  brown  organic  mat-  ^     33' 1         66*2 

ter  and  water 

Earthy  phosphates,  with  very  little  sandy  matter 
Alkaline  phosphate   and  chloride   with  little"! 

sulphate  J 


'7 


14-6 

29-2 

2-3 

4-6 

50- 

100-0 

smell. 

Examined 

22-3 

44-6 

20-6 

41-2 

7-1 

14-2 

No.  2. — Darker  in  colour,  and  having  but  little  smell, 
as  in  preceding  case ;  it  contained  no  uric  acid. 

Fifty  grains  gave — 
Oxalate  of  ammonia,  with  little  carbonate,  or-  \ 

ganic  matter  and  water  / 

Earthy  phosphates,  with  little  gritty  matter . . 
Alkaline  sulphates,  chlorides  and  phosphates,  T 

(both  potash  and  soda,  the  latter  most  abun-  > 

dant) J 

50-         100- 

The  last  specimen  is  evidently  older  and  in  a  more  advanced  state 
of  decomposition  than  the  other ;  its  odour  is  far  less  powerful  and 
offensive  ;  it  contains  little  or  no  uric  acid,  but  a  larger  proportion 
of  inorganic  substances*. 

It  is  difficult  to  imagine  a  manure  better  fitted  for  almost  uni- 
versal use  than  this  "  guano ; "  it  contains  in  a  highly  concentrated 
form  everything  that  plants  require  for  their  sustenance,  with  the 
exception  perhaps  of  potash,  which  however  is  often  abundantly 
supplied  by  a  soil  poor  in  other  respects. 

The  presence  of  a  large  quantity  of  oxalate  of  ammonia  is  a  cu- 
rious fact,  and  was  early  noticed ;  there  can  be  no  doubt  that  this 
substance  owes  its  existence  in  some  way  or  other  to  the  uric  acid 
contained  in  the  excrement  of  the  sea-birds,  to  the  decomposition  of 
which  the  guano-deposits  are  due.  We  can  easily  imagine  that  in 
this  mass  of  putrefying  substance,  kept  in  a  moistened  state  by  the 
dews  of  night,  a  decomposition  of  a  peculiar  kind  may  be  set  up  in 
the  uric  acid,  and  its  gradual  conversion  into  new  products,  among 

[*  On  the  composition  of  guano,  see  also  Phil.  Mag.,  S.  3.  vol.  xix.  p.  49.] 


Mr.  Cock  on  Artificial  XJranite.  387 

which  may  easily  he  oxalate  of  ammonia,  effected  perhaps  somewhat 
after  the  following  fashion : — 

Uric  acid C5  H2  N2  03 1        C  2  eq.  oxal.  acid  C4  06 

4  eq.  water H4       04  >  =  <  2  . .    ammonia       H6  N2 

1  eq.  oxyg.  from  air  O  J        Ll  ..  carb.acidC  02 

CsH6Ns08  C5H6N208 

This  view,  it  must  be  remembered,  is  merely  hypothetical,  yet  is 
borne  out  by  the  facts. 

The  only  case  in  which  oxalic  acid  is  known  to  arise  from  uric 
acid,  is  in  the  artificial  formation  of  allantoin  discovered  by  Liebig, 
and  in  which  uric  acid,  water  and  peroxide  of  lead  being  boiled 
together,  give  rise  to  oxalate  of  the  protoxide  of  lead,  allantoin  and 
urea ;  it  is  in  short  an  oxidizing  action,  so  far  resembling  the  one 
imagined,  but  more  complex. 

Uric  acid  (doubled)  C10  H4  N4  06  ]       f  Allantoin. .  . .  C4  H3  N2  03 

3  eq.  water Hg      03  >  =  I  Urea C2  H4  N2  02 

2. .  ox.  fromperox.  02J        (^2  eq. oxal. acid C4  06 

C10H7N4On  C10H7N4Ou 

It  is  very  unlikely  that  this  peculiar  mode  of  decomposition 
should  occur  under  the  circumstances  in  which  the  guano  is  pro- 
duced ;  urea  certainly  would  not  resist  destruction  a  week,  and  no 
doubt  the  allantoin  would  share  the  same  fate. 

It  was  thought  worth  while  nevertheless  to  examine  one  of  the 
specimens  (No.  1)  carefully  for  these  two  bodies,  a  portion  of  the 
substance  being  acted  upon  by  hot  water,  and  the  filtered  solution 
cautiously  evaporated  to  a  small  bulk,  whereupon  crystals  were 
abundantly  formed  on  cooling.  These  being  dissolved  in  hot  water, 
decolorized  with  animal  charcoal,  and  the  solution  once  more  con- 
centrated, a  second  crop  was  got,  but  slightly  coloured.  These 
however  turned  out  on  examination  to  be  nothing  but  oxalate  of 
ammonia.     The  search  for  urea  was  equally  unsuccessful. 

There  is  a  curious  relationship  between  the  three  bodies,  oxalate 
of  ammonia,  oxamide  and  allantoin,  the  only  difference  in  compo- 
sition being  the  diminishing  proportion  of  the  elements  of  water. 
Anhydrous  oxalate  of  ammonia  (doubled)  . .    C4  H6  N2  06 

Oxamide  (doubled)  C4  H4  N2  04 

Allantoin C4  H3  N2  03 

"  On  the  production  of  Artificial  Uranite,"  by  W.  J.  Cock,  Esq. 

The  subject  of  the  present  communication  was  observed  during  the 
preparation  of  the  oxide  of  uranium  from  its  mineral,  Pitchblende  ; 
it  was  obtained  as  follows  : — 

The  mineral  was  pulverized  and  well  calcined ;  it  was  then  di- 
gested with  diluted  nitric  acid,  which  dissolved  the  greater  part  of 
the  soluble  contents.  (From  this  solution  none  of  the  precipitate 
was  obtained.) 

The  undissolved  residuum  was  washed  and  dried,  and  again  cal- 
cined.    It  was  digested  in  nitric  acid  rather  stronger  than  before, 


388  Chemical  Society. 

and  gave  a  solution  of  a  darker  green  than  the  first.  This  solution 
was  left  several  weeks  in  open  vessels,  and  upon  its  being  drawn  off, 
a  quantity  of  the  green  precipitate  was  found  adhering  to  the  bottom 
and  sides  of  the  vessels. 

The  composition,  which  is  very  variable,  of  the  mineral  Pitchblende, 
as  given  by  Berthier  in  his  Traitd  des  Essais  par  la  voie  seche  from 
two  analyses,  is  in  the  100  parts, — 

Protoxide  of  uranium 51'6         60*0 

Carbonate  of  magnesia 3*3 

Peroxide  of  iron 7*2  2*5 

Alumina  (clay) 17*2  9-0 

Sulphuret  of  iron  and  copper 1*2  5*5 

Arsenical  pyrites  (iron) 5-8  9*2 

Sulphuret  of  lead 6*0  3*5 

Sulphuret  of  zinc , .  . .  1*4 

Carbonate  of  lime 2*2  2'2 

Water  and  bitumen 4*2  5*2 

98-7         98-5 
No  mention  is  here  made  of  the  phosphoric  acid  which  enters  into 
the  composition  of  the  artificial  uranite.    The  composition  of  the  na- 
tive uranite,  as  also  of  the  double  phosphate  of  uranium  and  copper 
(chalkolite),  are  thus  given  by  Berzelius  : — 

Uranite.       Chalkolite. 

Oxide  of  uranium    59'37         60-25 

Lime i 5-65 

Oxide  of  copper 8'44 

Barytes    1*51 

Magnesia  and  oxide  of  manganese  '19 

Phosphoric  acid 14'63         15*56 

Water 14'90         15*05 

Gangue    285             '70 

Fluoric  acid  and  oxide  of  tin  ... .  trace 

9910       lOO* 
It  appears  that  these  two  minerals  are  found  mixed  together  in  all 
proportions,  and  from  the  artificial  compound  which  forms  the  sub- 
ject of  the  present  notice,  containing  both  oxide  of  copper  and  lime, 
that  it  is  also  a  mixture  of  these  salts. 

The  following  analysis  of  the  "  Artificial  Uranite,"  made  under 
the  superintendence  of  Mr.  Parnell,  was  read  as  an  appendix  to  the 
above  j — 

Phosphate  of  uranium    49* 

Oxide  of  copper 19*5 

Lime    1*8 

Water 21*5 

Phosphoric  acid  in  combination  with"!         „  „ 

oxide  of  copper  and  lime  (loss)  . . . .  / 

100-00 
The  process  of  analysis  was  the  following : — 
(1.)  Having  previously  ascertained  by  a  qualitative  analysis  that 


Royal  Irish  Academy.  389 

the  sole  constituents  of  the  substance  are  phosphoric  acid,  peroxide 
of  uranium,  oxide  of  copper,  lime  and  water,  a  known  weight  was 
dissolved  in  hydrochloric  acid,  and  copper  was  precipitated  as  sul- 
phuret  by  transmitting  sulphuretted  hydrogen  gas  through  the  solu- 
tion. The  precipitated  sulphuret,  when  filtered  and  washed,  was 
digested  in  nitric  acid,  and  from  the  solution  thus  obtained,  oxide  of 
copper  was  precipitated  by  potash,  washed,  ignited  and  weighed. 

(2.)  The  solution,  separated  by  filtration  from  the  sulphuret  of 
copper,  was  next  evaporated  to  dryness  and  mixed  with  a  little  con- 
centrated sulphuric  acid  to  convert  phosphate  of  lime  into  sulphate, 
the  mixture  was  diluted  with  alcohol,  in  which  sulphate  of  lime  is 
quite  insoluble,  and  filtered.  The  sulphate  of  lime  was  washed  with 
alcohol,  dried,  ignited  and  weighed. 

(3.)  The  filtered  alcoholic  solution,  containing  phosphate  of  ura- 
nium dissolved  in  the  excess  of  sulphuric  acid,  was  evaporated  to 
dryness,  the  residue  digested  in  nitric  acid,  and  phosphate  of  ura- 
nium precipitated  from  the  acid  solution  by  ammonia.  This,  when 
washed  and  dried,  was  gently  ignited  and  weighed. 

(4.)  The  water  contained  in  the  substance  was  determined  by  ob- 
serving what  loss  in  weight  it  sustained  when  calcined  at  a  dull  red 
heat ;  and 

(5.)  The  remaining  ingredient,  the  phosphoric  acid  in  combina- 
tion with  oxide  of  copper  and  lime,  was  considered  as  the  deficiency 
on  the  weight  of  the  original  substance. 

"  Some  additional  Observations  on  the  Red  Oxalate  of  Chro- 
mium and  Potash,"  by  Robert  Warington,  Esq.  This  paper  has 
been  inserted  in  the  present  volume,  p.  201. 

ROYAL  IRISH  ACADEMY. 

[Continued  from  p.  233.] 

May  24,  1841  (Continued).— The  following  Note  "On  the  Force 

of  aqueous  Vapour  within  the  Range  of  atmospheric  Temperature," 

was  read  by  James  Apjohn,  M.D.,  M.R.I. A.,  Professor  of  Chemistry 

in  the  Royal  College  of  Surgeons. 

Having  had  it  in  contemplation  some  time  since  to  investigate  by 
means  of  an  indirect,  but  I  believe  a  very  accurate  process,  the  ca- 
loric of  elasticity  of  the  vapours  of  several  liquids,  I  found  myself 
stopped  on  the  threshold  of  the  inquiry  by  a  want  of  knowledge  of 
the  tension  of  such  vapours  at  different  temperatures ;  for,  with  the 
exception  of  the  vapours  of  water,  alcohol,  aether,  and  oil  of  turpen- 
tine, the  tension  of  no  others  had  been  made  the  subject  of  experi- 
ment ;  and  even  in  the  case  of  the  fluids  just  named,  the  results  re- 
corded in  the  books  appeared  to  me  very  far  from  being  of  such  a 
nature  as  to  preclude  the  necessity  of  further  research. 

The  method  which  I  intended  to  employ,  in  order  to  arrive  at  the 
latent  heats  of  vapours,  not  requiring  a  knowledge  of  their  tensions 
beyond  the  range  of  atmospheric  temperature,  it  occurred  to  me,  that 
the  necessary  data  for  the  solution  of  the  preliminary  problem  might 
be  obtained  with  facility,  and,  at  the  same  time,  with  much  precision, 
in  the  following  manner : — 


890  Royal  Irish  Academy :  Dr.  Apjohn  on  the 

Let  a  known  volume  of  dry  air  be  charged  with  moisture  at  any 
given  temperature,  and  let  the  expansion  produced  by  the  moisture 
be  accurately  noted.  The  pressure  being  also  measured  by  an  ac- 
curate barometer,  we  have  the  means  of  calculating  the  force  of  the 
vapour  which  has  produced  the  expansion.  For  if  v  be  the  volume 
of  the  dry  air,  and  v'  that  of  same  air  when  charged  with  moisture, 
/  the  force  of  the  vapour,  and  p  the  existing  atmospheric  pressure, 
we  shall  have 


from  which  we  deduce 


v'  =  v  x         — , 
P-f 


f=m**- 


It  was  not  my  original  intention  to  make  any  experiments  upon 
the  force  of  aqueous  vapour,  believing  the  table  which  I  have  hitherto 
employed,  and  which  was  calculated  by  the  author  of  the  article 
"  Hygrometry,"  in  Brewster's  Encyclopaedia,  from  the  experiments 
of  Dalton,  to  have  been  sufficiently  exact.  But  the  correctness  of 
this  table  having  been  indirectly  called  in  question  by  sk>  high  an 
authority  as  M.  Kupffer,  who  has  come  to  the  conclusion,  that  the 
table  of  the  force  of  aqueous  vapour,  given  by  a  German  meteorologist 
of  the  name  of  Kamtz,  is  alone  to  be  relied  upon,  I  resolved  to  com- 
mence with  the  vapour  of  water,  in  the  hope  that  I  might  be  able, 
by  the  results  of  direct  experiment,  to  corroborate  a  conclusion  pre- 
viously drawn  by  Professor  Lloyd,  from  a  discussion  of  some  hygro- 
metrical  observations  of  mine,  viz.  that  for  temperatures  within  the 
atmospheric  range,  the  table  of  Kamtz  is  less  accurate  than  that  of 
Dalton,  the  values  given  in  the  former  being  all  too  low. 

The  apparatus  I  have  employed  in  my  experiments  is  composed  of 
a  glass  ball  prolonged  on  the  one  side  into  a  short  tube,  furnished 
with  a  cap  and  stop-cock,  and,  on  the  other,  into  a  long  tube  of 
somewhat  smaller  diameter,  divided  into  100  equal  parts,  each  being 
•042  of  a  cubic  inch,  or  the  -001  of  the  total  capacity  of  ball  and 
tubes  down  as  far  as  the  division  marked  1000. 

The  first  step  consisted  in  filling  this  vessel  with  dry  air,  which 
was  done  in  the  following  manner :  into  the  extremity  of  the  gra- 
duated tubular  portion,  a  cork  pierced  by  a  small  tube,  open  at  both 
ends,  was  inserted,  and  this  tube  was  then  connected  with  the  orifice 
of  a  table  air-pump  usually  occupied  by  a  syphon  gauge.  The  stop- 
cock was  now  connected  with  one  end  of  a  long  tube,  packed  with 
fragments  of  fused  caustic  potash,  while  the  other  end  of  this  tube 
was  attached  by  means  of  a  slip  of  caoutchouc  to  a  second  tube 
passing  through  an  air-tight  cork  fixed  in  one  of  the  mouths  of  the 
bottle,  at  present  used  for  the  inhalation  of  chlorine.  This  bottle 
being  charged  with  oil  of  vitriol,  and  the  orifice  of  the  plate  of  the 
pump  being  closed,  the  pump  was  worked,  and  a  current  of  air  was 
thus  drawn  through  the  glass  vessel  for  about  fifteen  minutes,  which 
in  passing  through  the  oil  of  vitriol,  and  over  the  fused  potash,  was 
deprived  of  all  hygrometric  moisture.    The  included  air  being  now 


Farce  of  Aqueous  Vapour  at  Atmospheric  Temperatures.     391 

absolutely  dry,  the  stop-cock  was  closed,  and  the  small  tube  connect- 
ing the  air  vessel  with  the  pump  having  been  drawn  out  in  the  mid- 
dle, and  sealed  hermetically  by  means  of  a  spirit  lamp,  the  air  ap- 
paratus was  separated  from  the  potash  tube,  and  transferred  to  a  tall 
jar  containing  mercury,  after  which  the  sealed  end  of  the  small  glass 
tube  was  broken  beneath  the  surface  of  the  quicksilver.  The  ap- 
paratus, however,  being  now  completely  filled,  it  became  necessary 
to  remove  some  of  the  air,  and  this  was  done  by  opening  the  stop- 
cock very  gradually,  care  being  taken  that  during  this  manipulation 
the  external  mercury  should  be  higher  than  its  level  within  the  tu- 
bular portion.  The  entire  was  then  placed  in  a  small  room,  the 
temperature  of  which  was  found  not  to  vary  more  than  one  degree 
Fahrenheit  during  the  twenty-four  hours,  the  stop-cock  having  been 
first  attached  to  one  extremity  of  a  string,  which  was  carried  over  a 
fixed  pulley  placed  in  the  ceiling,  and  whose  other  end  carried  a 
counterpoise  by  which  the  air  vessel  was  kept  in  a  vertical  position, 
and  the  observer  was  enabled  readily  to  bring  the  mercury  within 
and  without  to  the  same  level,  before  he  registered  the  volume  of 
the  included  air. 

On  the  next  day,  after  the  apparatus  was  mounted,  and  the  four 
following  ones,  the  volume  of  the  dry  air,  its  temperature,  and  the 
existing  pressure  were  accurately  noted.  This  pressure,  which  was 
measured  by  a  portable  barometer  of  Newman's,  having  undergone 
a  variety  of  corrections,  for  the  capacity  of  the  cistern  compared  to 
that  of  the  tube,  for  the  excess  of  the  temperature  of  the  quicksilver 
over  32°,  for  capillarity,  and  for  a  constant  error  by  which  I  found 
my  barometer  affected,  when  compared  with  the  standard  instru- 
ment in  the  Observatory  of  Trinity  College,  I  reduced  by  calculation 
in  each  instance  the  observed  volume  of  air  to  what  it  would  be  at 
32°,  and  under  a  pressure  of  30,  using  for  the  expansion  of  air  the 
corrected  coefficient  ^^,  which  has  resulted  from  the  experiments 
of  Rudberg,  and  thus  obtained  the  following  numbers,  which,  it 
will  be  observed,  differ  very  little  from  each  other  : — 

1  911-11 

2 911-85 

3 910-21 

4 913-30 

5 911-72 

911*64,  therefore,  the  mean  of  the  five  observations,  may  be  as- 
sumed as  the  true  volume  of  the  included  dry  air,  at  32°,  and  under 
a  pressure  of  30. 

The  volume  of  the  dry  air  being  determined,  the  next  step  was  to 
charge  it  with  moisture.  In  order  to  accomplish  this,  the  air  vessel 
was  lifted  by  means  of  the  string,  so  as  that  the  mercury  within  should 
be  about  an  inch  higher  than  the  external  mercury,  and  distilled 
water  was  then  poured  into  the  upper  cavity  of  the  stop- cock,  so  as 
completely  to  fill  it.  The  stop-cock  was  now  cautiously  turned,  so 
as  to  admit  the  entrance  of  the  moisture  guttatim  •  and  more  water 
being  occasionally  poured  on,  this  manipulation  was  repeated  until  the 
mercury  within  came  to  be  covered  by  a  film  of  water  of  about  one- 


392  Royal  Irish  Academy :  Dr.  Apjohn  on  the 

tenth  of  an  inch  in  thickness.  The  stop-cock  was  now  closed,  and 
the  apparatus  being  lowered,  the  whole  was  left  to  itself  until  the 
following  day,  when  the  first  of  a  series  of  observations,  continued 
for  twenty  successive  days,  was  made,  each  comprehending  the  vo- 
lume of  the  moist  air,  the  pressure,  and  the  temperature  both  of  the 
air  and  of  the  mercury  in  the  barometer.     To  deduce  from  these  by 


the  formula /  = 


X  p,  the  force  of  vapour,  it  was  necessary, 


in  the  first  instance,  to  apply  to  p  all  the  corrections  already  ex- 
plained, and  in  addition  to  raise  91T64,  the  volume  of  the  dry  air, 
to  what  it  would  be  at  the  temperature  and  pressure  of  the  moist 
air,  as  noted  in  each  observation.  But,  as  this  involved  tedious 
arithmetical  computations,  and  as  the  thermometer  during  the  per- 
formance of  the  twenty  experiments  varied  only  about  15°,  I  came 
to  the  resolution,  being  at  the  time  upon  the  eve  of  leaving  town  for 
a  couple  of  months,  to  postpone  the  calculations  until  I  should  be 
possessed  of  data  applicable  to  the  solution  of  the  problem  I  had  un- 
dertaken, throughout  a  more  extended  range  of  temperature. 

Accordingly,  in  November  last,  I  resumed  the  subject  with  the 
very  same  apparatus,  which  had  been  left  statu  quo  in  the  interval, 
and  succeeded  in  completing  a  series  of  forty-five  additional  observa- 
tions, extending  nearly  as  low  as  32°,  and  which  I  had  every  reason 
to  expect  would  lead  to  satisfactory  results.  Upon,  however,  sub- 
mitting the  whole  to  calculation,  I  have  been  led  to  the  mortifying 
conviction,  that  in  consequence  either  of  the  absorption  of  the  oxygen 
by  the  mercury  and  brass-work,  or  some  accident  which  befel  the 
apparatus  during  my  absence  from  town,  the  entire  of  the  latter 
series  of  observations  is  of  no  value,  as  they  lead  to  results  for  the 
force  of  aqueous  vapour,  which  are  certainly  greatly  below  the  truth. 
Upon  the  present  occasion,  therefore,  I  can  direct  attention  only  to 
the  observations  made  in  July  and  August  last.  These  are  contained 
in  the  following  table,  and,  as  has  been  already  stated,  they  amount 
to  twenty  in  number,  the  highest  temperature  having  been  65°,  and 
the  lowest  490,6.  The  numbers  in  the  last  column  represent  the 
bulks  which  the  911*64  volumes  of  dry  air  would  have,  if  reduced  to 
the  temperature  t,  and  the  corrected  pressure  p. 

Table  I. 


Tempera- 

911-64 re- 

v'. 

t. 

p  observed. 

ture  of 
barometer. 

p  corrected. 

duced  to  t  and 
p  corrected. 

1001 

60-4 

1  29'450 

59-9 

29-430 

982-82 

1001-5 

59-8 

29-364 

60-1 

29-338 

984-77 

997 

60 

29-548 

60 

29-524 

978-94 

984 

59-1 

29-822 

59-5 

29-807 

967-97 

977 

58-4 

29-980 

58-6 

29-971 

961-38 

984 

58-4 

29-780 

58-9 

29-767 

967-97 

991 

59 

29-624 

59-4 

29-607 

974-33 

Force  of  Aqueous  Vapour  at  Atmospheric  Temperatures.   393 
Table  (continued). 


Tempera- 

911-64 re- 

t/. 

t. 

p  observed. 

ture  of 
barometer. 

p  corrected. 

duced  to  t  and 
p  corrected. 

983-5 

59-4 

29-862 

59-8 

29-847 

967-23 

979-5 

60-2 

30-100 

60-6 

30-086 

962-69 

977-5 

61-2 

30-132 

61-3 

30-165 

960-35 

983 

61-6 

30-05 

62-2 

30-037 

965-18 

973-3 

62-2 

30-230 

62-4 

30-212 

960-69 

978-4 

61-6 

30-214 

62-2 

30-197 

960-06 

983-5 

63-1 

30-156 

63-6 

30-131 

964-93 

987-5 

64-3 

30-130 

64-7 

30-104 

968-01 

991 

64-1 

30-032 

64-6 

30-005 

970-83 

994-5 

64-8 

29-989 

65 

29-961 

973-55 

994-5 

65 

29*972 

66 

29-940 

974-61 

989 

65-2 

30-152 

66-5 

30-120 

969-12 

1000 

64-8 

29-834 

65 

29-306 

978-62 

From  the  first,  last,  and  second  last  columns  of  the  preceding 
table,  the  force  of  aqueous  vapour  has  been  calculated  in  the  manner 
already  explained.  The  values  thus  obtained  are  exhibited  in  the 
second  column  of  Table  II.  Column  1  contains  the  temperatures ; 
column  3  the  tensions,  as  deduced  from  Dalton's  experiments ;  and 
column  4  the  same  as  given  by  Kamtz. 

Table  II. 


1. 

2. 

3. 

4. 

Dalton. 

Kamtz. 

60-4 

•5345 

•5302 

•5125 

59-2 

•4908 

•5197 

•5023 

60- 

•5348 

•5232 

•5061 

59-1 

•4855 

•5077 

•4893 

58-4 

•4917 

•4960 

•4768 

58-4 

•4849 

•4960 

•4768 

59- 

•4980 

•5060 

•4875 

59-4 

•4937 

•5128 

•4949 

60-2 

•5169 

•5265 

•5093 

61-2 

•5292 

•5444 

•5261 

61-6 

•5445 

•5517 

•5343 

62-2 

•5412 

•5628 

•5458 

61-6 

•5660 

•5517 

•5343 

63-1 

•5689 

•5798 

•5615 

64-3 

•5941 

•6033 

•5860 

64-1 

•6107 

•5993 

•5824 

64-8 

•6311 

•6133 

•5949 

65- 

•5988 

•6173 

•5985 

65-2 

•6054 

•6214 

•6029 

64-8 

•6372 

•6133 

•5949 

Phil.  Mag.  S.  3.  Vol.  21.  No.  139.  Nov.  1842.        2  D 


394-  Royal  Irish  Academy. 

When  the  corresponding  numbers  in  the  three  columns  are  com- 
pared, it  will  be  at  once  observed,  that  the  values  of  f,  investigated 
by  the  method  just  explained,  are  somewhat  less  than  those  extracted 
from  the  table  I  have  been  hitherto  in  the  habit  of  using ;  but  that 
they  are  considerably  greater  than  the  values  of  Kamtz,  the  differ- 
ences being  generally  better  than  twice  as  great  in  the  latter  in- 
stance as  in  the  former.  This  will  be  more  manifest  by  taking  a 
mean  of  the  different  results  in  column  2,  and  comparing  it  with  the 
force  of  vapour  corresponding  to  the  same  temperature  as  given  in 
the  two  other  tables.  Now,  the  mean  of  the  temperatures  is  61°'63, 
the  quotient  got  by  dividing  their  sum  by  twenty.  But  the  corre- 
sponding mean  value  of  /,  in  column  2,  must  be  differently  calcu- 
lated, seeing  that  the  temperature  and  the  corresponding  tensions  of 
the  vapour  augment  at  a  very  different  rate.  For  temperatures, 
in  fact,  in  arithmetic  progression,  the  corresponding  tensions  are  in 
geometric  progression,  and,  although  this  is  well  known  to  be  but  an 
approximate  law,  it  may  be  considered  as  rigorously  true  for  the  limit- 
ed range  of  temperature  within  which  my  experiments  have  been  made. 
To  calculate,  therefore,  the  mean  force  of  vapour,  as  deducible  from 
the  numbers  in  column  2,  and  which  must  correspond  to  the  tempe- 
rature 610,63,  it  is  only  necessary  to  add  together  the  logarithms  of 
the  numbers  in  this  column,  and  divide  their  sum  by  twenty,  and 
the  quotient  will  be  the  logarithm  of  the  mean.  When  this  process 
is  gone  through,  the  mean  logarithm  is  found  to  be  "73699,  and  the 
corresponding  number  *54575.  The  following,  therefore,  are  the 
tensions  of  aqueous  vapour  at  610-63,  as  deduced  from  my  experi- 
ments, and  as  extracted  from  the  tables  of  Dal  ton  and  Kamtz. 
My  experiments.  Dalton.  Kamtz. 

61°'63 -5457 '5523 '5349 

Difference  between  Dalton's  number  and  mine =  +  "0066 

Difference  between  Dalton's  number  and  that  of  Kamtz  =  +  '0174. 

It  thus  appears,  that  the  result  at  which  I  have  arrived  is  some- 
what less  than  the  Daltonian  number,  but  considerably  greater  than 
that  given  by  Kamtz ;  and  that,  therefore,  my  experiments,  as  far 
as  they  have  been  discussed,  give  at  least  a.  prima  facie  countenance 
to  the  opinion,  that  the  values  of  the  elastic  force  of  aqueous  vapour, 
as  given  by  the  latter  philosopher,  are,  at  and  about  610-63,  below 
the  truth. 

Before,  however,  this  conclusion  can  be  considered  as  fully  esta- 
blished, and  before  we  can  judge  correctly  of  the  amount  of  the 
errors  by  which  his  table  is  affected,  it  will  be  necessary  to  inquire 
whether  the  thermometer  I  have  employed  be  a  true  one.  This 
essential  inquiry  I  have  been  enabled  to  institute  by  my  friend  Pro- 
fessor Lloyd,  who  has  put  into  my  possession,  for  the  purpose,  a 
thermometer  given  him  by  Professor  John  Phillips,  together  with  a 
table  of  differences  between  it  and  the  standard  thermometer  belong- 
ing to  the  Royal  Society.  Upon  a  comparison  of  the  two  instru- 
ments, I  find,  that  at  and  about  60°,  the  thermometer  I  have  em- 
ployed stands  *6  of  a  degree  higher  than  that  lent  me  by  Professor 
Lloyd,  while  the  latter  stands  *3  of  a  degree  higher  than  the  standard 
in  possession  of  the  Royal  Society ;  so  that  the  indications  of  my 


Royal  Irish  Academy.  395 

instrument  are  at  60o,9-10ths  of  a  degree  higher  than  the  truth. 
If  such  he  the  case,  *5457,  instead  of  being  the  force  of  vapour  at 
61°-63,  is  the  force  at  6T63  —  0*9  =  60°73 ;  and  to  compare  the 
result  of  my  experiments  with  the  tables  of  Dalton  and  Kiimtz,  it 
is  only  necessary  to  extract  from  these  the  values  of  the  force  of 
vapour  corresponding  to  the  temperature  60°* 73. 

My  experiments.  Dalton.  Kamtz. 

60°-73 -5457 "5361 -5157 

Difference  between  Dalton's  number  and  mine —  "0096. 

Difference  between  Dalton's^  number  and  that  of  Kamtz    .  4-  *0184. 

The  consideration,  therefore,  of  the  error  of  my  thermometer,  and 
the  allowance  made  for  it,  only  strengthens  the  conclusion  already 
arrived  at ;  and  I  do  not  now  feel  any  difficulty  in  giving  it  as  my 
deliberate  opinion,  that  the  table  of  the  force  of  vapour  given  by 
Kamtz  is,  within  the  atmospheric  range  of  temperature,  erroneous, 
his  values  being  all  too  low. 

June  14,  1841.— The  Rev.  H.  Lloyd,  V.P.  read  a  "Note  on  the 
mode  of  observing  the  vibrating  Magnet,  so  as  to  eliminate  the  Effect 
of  the  Vibration." 

The  following  modification  of  one  of  the  methods  proposed  by 
Gauss  for  the  attainment  of  this  end,  appears  to  combine  the  greatest 
number  of  advantages ;  namely,  to  take  three  readings,  at  the  times. 

t  —  T,     t,     t+T; 

t  being  the  epoch  for  which  the  position  of  the  magnet  is  desired,  and 
T  its  time  for  vibration*.  In  order  to  show  that  this  method  is  ade- 
quate, it  is  necessary  to  deduce  the  equation  of  motion  of  a  vibrating 
magnet  in  a  retarding  medium. 

Let  X  denote  the  horizontal  part  of  the  earth's  magnetic  force ; 
q  the  quantity  of  free  magnetism  in  the  unit  of  volume  of  the  sus- 
pended magnet,  at  the  distance  r  from  the  centre  of  rotation ;  and  9 
the  deviation  of  the  magnet  from  its  mean  position.  The  moment 
of  the  force  exerted  by  the  earth  on  the  element  of  the  mass,  dm,  is 

X  q  r  d  m  sin  0 ; 
and  the  sum  of  the  moments  of  the  forces  exerted  upon  the  entire 
magnet  is 

X  jW/  sin  0 ; 
where  jo,  denotes  the  value  of  the  integral  fq  r  d  m,  taken  between 
the  limits  r  —  +  I,  2  I  being  the  length  of  the  magnet. 

Again,  the  velocity  being  small,  the  resistance  may  be  assumed  to 
be  proportional  to  the  velocity.  Accordingly,  if  ca  denote  the  angular 
velocity,  the  retarding  force  due  to  resistance,  upon  any  element  of 
the  surface,  d  s,  at  the  distance  r  from  the  centre  of  motion,  is 

—  Kdsrw; 
and  the  entire  EAoment  of  this  force  upon  the  whole  magnet  is 


Ku>fr*ds=-Kuj  rr*dm] 


*  In  practice,  it  is  sufficient  to  take  the  nearest  whole  number  of  seconds 
for  the  value  of  T. 

2D2 


396  Royal  Irish  Academy. 

where  H  =  — —     The  ratio  H  is  constant  for  all  bodies  of  pris- 
ds  r 

matic  form ;  and  for  these,  therefore,  the  moment  of  resistance  is 

_MK 

H    U'' 

M  denoting  the  moment  of  inertia / r2  dm. 

The  differential  equation  of  motion  is,  therefore, 

dta       Xu   .    a       K 

— —  =  — -f-  sin  9 to. 

dt        M  H 

rf  9 

But  w  =  —  — - ;  and,  0  being  small,  we  may  substitute  0  for  sin  0. 
dt 

The  equation  thus  becomes 

d^  +  Kdj_      Xj, 
dt       Hd*x  M 

Making,  for  abridgement,  —  =  2  A,  — |-  =  B-,  the  integral  is 


0  =  (c  cos  V  B2  —  A3 .  t  +  c'  sin  V  B*  —  A2 .  *)  e~  A '. 
But,  A  being  small,  we  have  approximately 
e-A'  =  l-A*; 
and,  if  T  denote  the  time  of  vibration, 

VBa-Aa.T  =  tf. 
Hence  the  preceding  equation  may  be  put  under  the  form 

0=(1  —  A/)  (ccosifL  4.  c'sin*4Y 

Now,  let  0,  and  0'  denote  the  values  of  0,  when  t  becomes  /  —  T 
and  t  +  T.     It  will  be  seen  at  once,  on  substitution,  that 

0,  +  2  0  +  0'  =  0. 

Hence  by  combining  the  three  readings  according  to  the  preceding 
formula,  the  deviation  of  the  magnet  from  its  mean  position,  arising 
from  the  vibratory  movement,  is  completely  eliminated ;  and  it  will 
readily  appear  that  the  same  result  may  be  attained  by  any  greater 
number  of  readings,  taken  and  combined  according  to  the  same 
law. 

Now,  let  the  value  of  0  contain  an  additional  term,  +  p  t,  propor- 
tional to  the  time  :  or,  in  other  words,  let  us  suppose  that  there  is  a 
progressive  change  of  the  declination,  which  may  be  regarded  as 
uniform  during  the  whole  interval  of  observation,  "it  is  then  mani- 
fest that  0/-J-20  +  0'  =  4^f;  and  accordingly  that  the  quantity 

£(0/  +  20  +  0') 
will  give  the  mean  place  of  the  magnet  corresponding  to  the  epoch  t. 


Royal  Astronomical  Society,  397 

The  supposition  of  a  uniform  change  can,  however,  be  regarded  as 
an  approximation  to  the  truth,  only  when  the  interval  of  time  be- 
tween the  first  and  last  reading  is  very  small,  in  comparison  with  the 
interval  between  the  successive  maxima  and  minima,  in  the  fluctua- 
tions of  the  irregular  movement.  Hence,  we  may  conclude,  that  it  is 
important,  in  the  first  place,  to  employ  three  readings  in  preference 
to  any  greater  number ;  and,  secondly,  that  it  is  desirable  that  the 
time  of  vibration  of  the  magnet  itself  should  be  as  small  as  possible, 
consistently  with  the  accuracy  of  its  indications  in  other  respects. 


ROYAL  ASTRONOMICAL  SOCIETY. 
[Continued  from  p.  61.] 

January  14, 1842. — I.  Observations  of  Halley's  Comet,  made  at  the 
Observatory  of  Geneva  in  the  years  1835  and  1836.  By  M.  Miiller, 
under  the  direction  of  M.  Gautier,  Director  of  the  Observatory.  Com- 
municated by  Sir  J.  F.  W.  Herschel,  Bart. 

These  observations  were  made  on  fifty-two  nights,  beginning  with 
August  31,  1835,  and  ending  with  May  7,  1836 ;  of  which  thirty- 
one  were  before  the  perihelion  passage  of  the  comet,  and  twenty- 
one  after  the  passage.  The  instrument  used  is  an  equatoreal  of 
Gambey,  whose  telescope  has  an  object-glass  of  four  French  inches 
diameter,  and  of  forty-two  French  inches  focal  length.  The  decli- 
nation circle  and  the  hour  circle  of  the  instrument  are  each  thirty 
inches  in  diameter ;  the  former  being  divided  to  every  three  minutes 
of  a  degree,  and  by  means  of  its  verniers  giving  arcs  of  3" ;  and  the 
latter  being  divided  in  time,  and  by  means  of  its  verniers  giving  the 
fifth  part  of  seconds  of  time.  The  times  were  taken  with  a  clock  by 
Lepaute,  which  was  every  evening  compared  with  the  transit  clock. 
The  index  corrections,  obtained  chiefly  by  observations  of  stars  found 
in  the  Astronomical  Society's  Catalogue,  and  whose  observed  places 
were  compared  with  the  places  taken  from  that  Catalogue,  and  from 
Pond's  Catalogue  of  1112  stars,  were  very  consistent  throughout  the 
whole  series  of  observations,  and  show  that  the  firmness  of  the  in- 
strument, as  well  as  its  state  of  adjustment,  were  highly  satisfactory. 
Absolute  observations  of  both  elements  were  obtained  in  every  in- 
stance by  reading  off  both  circles  ;  this  method  being  preferred  by 
M.  Gautier  to  differential  observations  with  a  micrometer.  A  reticu- 
lar micrometer,  made  of  fine  plates  of  metal,  was  used,  the  faintness 
of  the  comet  scarcely  ever  admitting  of  any  illumination  of  the  field. 

In  the  reduction  of  the  observations,  the  mean  refractions  were 
computed  for  all  the  observations  of  the  comet  and  the  comparison- 
stars  ;  and  the  instrumental  right  ascensions  and  north  polar  di- 
stances are  given,  cleared  of  the  effects  of  them.  The  index  cor- 
rections obtained  from  all  the  observations  of  stars  are  also  given. 
It  is,  however,  left  to  those  who  may  be  desirous  of  using  the  ob- 
servations of  the  comet  to  apply  them,  and  also  the  effects  of  paral- 
lax, to  the  observed  places. 

The  height  of  the  observatory  above  the  level  of  the  sea  (above 
400  metres)  caused  the  comet  to  be  visible  at  this  observatory  longer 
than  at  most  other  places  in  Europe ;  and  the  author  hopes  that  the 


398  Royal  Astronomical  Society. 

circumstance  may  render  the  latter  part  of  the  series  especially  valu- 
able, the  southern  position  of  the  comet  and  the  unfavourable  state 
of  the  weather  causing  the  observations  of  it  to  be  in  general  very 
scarce,  after  its  perihelion  passage. 

II.  Note  on  the  Masses  of  Venus  and  Mercury.  By  R.  W.  Roth- 
man,  Esq.  The  following  is  the  conclusion  of  this  note,  the  whole 
of  which  is  given  in  the  Society's  Monthly  Notices  for  January. 

On  the  whole,  it  is  very  remarkable  that  the  planetary  masses 
given  in  the  Me'canique  Celeste  (vol.  iii.  p.  61),  satisfy  the  secular 
motions  affecting  the  orbit  of  Venus  much  better  than  the  masses  of 
later  astronomers.  It  appears  that  in  later  times  the  mass  of  Mer- 
cury has  been  too  much  increased,  and  that  of  Venus  too  much  di- 
minished. What  has  been  previously  remarked  concerning  the 
masses  of  Venus  and  Mercury  is  confirmed  by  the  motion  of  the 
node  of  Mercury.  If  this  motion  be  calculated  by  theory  with  the 
masses  of  the  Mecanique  Celeste,  the  result  agrees  almost  exactly 
with  the  motion  determined  from  observation  by  Lindenau. — See  his 
Tabula  Mercurii,  p.  9. 

III.  Observations  of  the  Immersion  of  p1  Leonis  behind  the  Dark 
Limb  of  the  Moon.     By  R.  Snow,  Esq. 

The  observed  Ashurst  sidereal  time  of  the  immersion  was  15h 
37m  23s*  9.  The  observation  was  made  with  a  power  of  75  on  the 
telescope  of  the  five-feet  equatoreal,  under  very  favourable  circum- 
stances. 

IV.  Extract  of  a  letter  from  Professor  Encke  to  Mr.  Airy,  dated 
20th  December,  1841.  Translated  from  the  German.  Communicated 
by  G.  B.  Airy,  Esq.  This  communication  will  be  found,  entire,  in 
the  preceding  volume,  p.  137. 

V.  Comparisons  of  the  Planet  Venus  in  Right  Ascension  and 
N.  P.  D.  with  the  Star  A.  S.  C.  423,  made  with  the  Equatoreal  In- 
strument of  the  Observatory  at  Ashurst,  on  April  9,  1841.  By  R. 
Snow,  Esq. 

The  equatoreal  instrument  employed  for  these  observations  is  of 
Fraunhofer's  construction,  and  furnished  with  clockwork ;  the  ob- 
ject-glass is  of  five  feet  focal  length,  and  of  four  inches  aperture.  It 
is  supported  on  a  Very  firm  pier,  and  retains  its  position  very  well. 

The  observations  were  made  with  a  position  micrometer,  adjusted 
for  transit  and  declination  observations.  They  consist  of  thirty 
transits  of  the  star  and  of  the  first  limb  of  Venus  over  the  meridian 
wire,  and  of  nine  micrometrical  measures  of  the  differences  of 
N.  P.  D.  of  the  star  and  the  south  limb  of  the  planet :  the  corrected 
sidereal  times  of  the  observations  are  given. 

The  value  of  a  revolution  of  the  micrometer-screw  had  been  de- 
termined by  400  transits  of  stars  near  the  equator.  Measures  of  the 
semidiameter  of  Venus  were  made  at  the  same  time,  by  which  it 
was  found  that  the  measured  value  exceeded  the  tabular  value  given 
in  the  Nautical  Almanac  by  8**1. 

The  circumstances  of  the  observations  were  favourable. 

VI.  Reduction  of  Mr.  Snow's  Observations  of  Venus  and  the  Star 
A.  S.  C.  423,  with  some  remarks  upon  the  employment  of  equa- 


Royal  Astronomical  Society.  399 

toreals  in  Planetary  Observations.     By  the  Rev.  Richard  Sheep- 
shanks. 

Mr.  Snow's  observations  admitted  of  being  so  grouped  as  to  fur- 
nish four  sets  of  comparisons  in  right  ascension  and  five  sets  in  de- 
clination. The  effects  of  parallax  and  refraction  were  computed  by 
the  formulae  used  at  Greenwich  (Greenwich  Observations,  1836, 
pages  lxiv.  and  lxv.).  The  right  ascension  of  the  star  was  taken 
from  Lord  Wrottesley's  Catalogue,  the  declination  from  the  Astro- 
nomical Society's  Catalogue,  and  the  semidiameter  of  Venus  from 
Mr.  Snow's  Observations ;  and  thus  the  right  ascension  and  declina- 
tion of  the  pJanet  were  obtained  for  the  Ashurst  sidereal  times  of 
observation  and  compared  with  the  places  interpolated  from  the 
Nautical  Almanac  for  the  same  times.  The  resulting  corrections  to 
be  applied  to  the  right  ascensions  and  declinations  of  the  Nautical 
Almanac  are  as  follow  : — 


Right  Ascension. 

Declination. 

—  1*10  from  15  obs. 

+  3*1  from  1  obs. 

-1*32  ...     5  ... 

+  5-4  ...     1    ... 

-1-25  ...     5  ... 

+  5-3  ...     4    ... 

-1-27  ...     5  ... 

+5-2  ...     2    ... 

+  3-6  ...     1    ... 

—  1-19  ...  30  ..  . 

+  4-9  ...     9   .— 

The  mean  epoch  is  about  8h  30m  Greenwich  mean  solar  time. 

The  author  remarks  generally  with  respect  to  the  treatment  of 
such  observations,  that  they  may  be  boldly  grouped  without  sensible 
error,  so  as  to  make  one  reduction  serve  for  a  considerable  number 
of  observations ;  and  that  to  ensure  the  greatest  facility  for  group- 
ing, the  observations  of  one  element  (if  both  cannot  be  made  simul- 
taneously) should  be  repeated  several  times  as  rapidly  as  possible 
alternately  with  similar  sets  of  observations  of  the  other  element. 

"With  respect  to  the  value  of  such  observations,  the  results  above 
given  will  show  that  an  equatoreal,  when  thus  used,  is  no  mean  rival 
to  meridian  instruments.  The  star  can  be  subsequently  determined 
with  any  required  degree  of  accuracy,  and  the  observations  can  be 
made  with  as  great  freedom  from  constant  error  with  an  equatoreal 
as  in  the  meridian.  In  this  latter  respect,  indeed,  the  power  of  re- 
petition gives  to  the  equatoreal  a  great  superiority,  and  may  be  made 
to  counterbalance  the  disadvantages  arising  from  want  of  steadiness. 
The  last-named  quality  can,  however,  in  most  instances,  be  obtained 
in  as  great  a  degree  as  is  requisite.  The  hour-circle  being  firmly 
clamped,  if  the  instrument  be  well  balanced,  sudden  changes  can 
arise  only  from  careless  handling. 

The  supposed  uncertainty  and  instability  of  the  adjustments  are 
probably  the  principal  obstacle  to  the  free  use  of  equatoreals  in  En- 
gland ;  but  the  author  considers  that  most  equatoreals  can  be  ad- 
justed very  nearly,  and  that  when  ordinary  care  has  been  taken,  the 
position  remains  sufficiently  permanent ;  and  it  is  certain  that  when 
rationally  used,  the  effect  of  any  unavoidable  derangement  is  so  nearly 
annihilated  as  to  be  quite  insensible.     The  difficulty  of  performing 


400  Royal  Astronomical  Society. 

the  adjustments  of  an  equatoreal  is  very  trifling,  if  it  be  methodically 
undertaken,  and  the  residual  errors  much  smaller  than  would  at  first 
sight  seem  possible.  With  well-turned  collars  and  pivots  an  error 
of  half  a  minute,  arising  from  flexure  or  other  causes,  must  be  looked 
upon  as  an  impossible  quantity,  in  which  case  the  differential  effects 
upon  objects  in  the  zodiac  might  be  disregarded.  With  respect  to 
methods  of  observing,  the  author  recommends  that  the  telescope  be 
moved  in  declination  like  a  transit,  in  order  that  the  star  and  planet 
may  pass  over  the  same  part  of  the  wire.  In  this  case  reliance  is 
placed  only  on  the  adjustment  of  the  cross-axis ;  but  when  the  de- 
clination is  not  changed,  it  is  presumed  that  the  position  of  the  wire 
is  correct ;  and  this  can  be  ascertained  with  only  a  moderate  degree 
of  certainty.  In  equatoreals  which  can  be  reversed  in  every  position, 
the  observations  should  be  made,  one  group  in  one  position,  and  the 
second  in  the  position  reversed.  The  best  wiring  for  such  observa- 
tions, the  author  considers  to  consist  of  three,  five,  or  seven  im- 
movable wires,  at  equal  distances,  and  parallel  to  the  meridian, 
transit- wires,  in  fact,  and  seven  equidistant  wires  at  right  angles  to 
these,  at  5'  interval,  the  plate  which  carries  the  latter  wires  being 
moved  by  a  micrometer-screw.  The  advantages  of  this  system  are 
a  saving  of  time  in  screwing  the  micrometer,  less  wear  of  the  screw, 
and  less  dependence  on  it  for  large  intervals. 

Thus  far  it  has  been  shown,  that  an  equatoreal  instrument  may 
be  made  to  rival  meridian  instruments,  by  the  bestowal  of  a  little 
more  time  and  trouble  ;  there  are,  however,  many  cases  where  the 
equatoreal  is  more  convenient,  and  many  where  it  can,  and  the 
others  cannot  be  used. 

A  planet  which  comes  to  the  meridian  at  a  late  or  inconvenient 
hour  of  the  night  may  be  observed  several  hours  earlier  with  the 
equatoreal.  In  so  variable  a  climate  as  ours,  it  is  not  too  much  to 
say,  that  the  number  of  good  planetary  observations  might  be  thus 
very  much  increased ;  and  if  an  equatoreal  were  steadily  directed  to 
this  object  in  the  southern  hemisphere,  to  meet  the  case  where  the 
planet  has  considerable  south  declination,  we  should  soon  have  the 
materials  by  which  the  present  sufficiency  of  theory  might  be  satis- 
factorily tested.  The  superior  planets  cannot  always  be  observed  in 
full  daylight  with  large  meridian  instruments,  yet  equatoreals  of 
even  a  small  size  might  be  made  to  determine  their  places  with  great 
accuracy  after  sunset.  Again,  large  equatoreals,  which  are  now 
tolerably  abundant,  might  take  charge  of  the  minor  planets.  Micro- 
metrical  observations  only  have  been  taken  notice  of  in  the  prece- 
ding remarks,  the  divided  circles  of  the  instrument  being  considered 
only  as  finders,  and  for  performing  the  adjustment,  though  in  some 
instruments  they  are  large  and  good  enough  to  be  used  in  differen- 
tial observations.  Still  the  proper  use  of  the  equatoreal  is  the  as- 
certaining of  small  differences  by  means  of  the  micrometer  and 
time. 

In  conducting  the  observations,  the  author  recommends  that  there 
should  be  made  each  night  two  or  three  transits  of  the  star  of  com- 
parison, and  of  two  other  stars,  one  above  and  one  below  it  a  few 


Institution  of  Civil  Engineers.  401 

degrees,  the  instrument  being  clamped  in  right  ascension,  by  which 
means  it  would  be  made  evident  whether  the  derangement  of  the 
adjustment  had  any  sensible  effect  upon  the  place  of  the  planet.  It 
is  the  want  of  observations  to  accuse  derangement  which  makes  the 
stars  observed  as  moon-culminators  less  satisfactory  than  if  they 
were  more  widely  spread  in  declination. 

With  respect  to  observations  of  the  moon,  the  author  mentions 
one  set,  originally  suggested  by  Struve,  but  never  carried  into  effect. 
There  are  three  observations  which  might  be  made  when  a  bright 
star  is  occulted  by  or  reappears  from  under  the  moon's  bright 
limb : — 

1 .  The  time  of  disappearance  or  reappearance  of  the,  star. 

2.  Micrometrical  measures  of  distance  between  the  star  and  the 
moon's  bright  limb,  the  clock-work  and  the  wire  micrometer  with 
the  slipping  piece  being  used. 

[This  is  the  common  observation  of  distance,  and  might  be  use- 
fully applied  to  the  case  of  a  near  approach.] 

3.  Differences  of  right  ascension  between  the  moon  and  star,  the 
hour-circle  being  clamped  as  in  ordinary  transit  observations. 

If  the  place  of  the  moon  be  computed  from  these  three  observa- 
tions, we  ought  to  arrive  at  the  same  result ;  and  if  we  do  not,  the 
difference  between  the  first  and  second  result  arises  from  the  moon's 
irradiation,  and  will  give  a  measure  of  it ;  also  a  difference  between 
the  second  and  third  results  would  show  some  error  in  the  mode  of 
taking  the  transit  of  the  moon's  limb,  which  is  at  present  rather  a 
doubtful  point  in  practical  astronomy.  If  by  certain  corrections, 
constant  either  to  the  observer  or  the  telescope,  these  results  can 
be  made  to  agree  in  each  case,  and  always  the  longitude  might  be 
determined  in  a  shorter  period,  though  with  more  calculation  than 
at  present,  and  a  greater  certainty  be  obtained  from  transits  of  the 
moon's  limb. 

In  conclusion,  the  author  hopes  that  the  attention  of  persons  who 
possess  good  equatoreals  may  be  directed  to  the  planets  whenever 
those  bodies  are  favourably  situated  with  respect  to  an  observable 
star.  The  adjustment  is  really  nothing,  and  if  pairs  of  stars  above 
and  below  be  observed,  any  error  arising  from  mal-adjustment  can 
be  ascertained  and  allowed  for.  The  artist  will  take  care,  if  warned, 
that  the  cross-axis  shall  be  at  right  angles  to  the  polar  axis,  and  the 
reductions,  in  ordinary  cases,  are  very  trifling,  especially  if  by  ju- 
dicious grouping  one  reduction  is  made  to  serve  for  several  observa- 
tions. 


INSTITUTION  OF  CIVIL  ENGINEERS. 

May  3,  1842. — "  Description  -of  the  Tunnels,  situated  between 
Bristol  arid  Bath,  on  the  Great  Western  Railway,  with  the  methods 
adopted  for  executing  the  works."  By  Charles  Nixon,  Assoc.  Inst. 
C.E. 

The  works  described  in  this  paper  comprised  a  large  quantity  of 
heavy  earth- work  in  tunnels,  &c. ;  they  were  commenced  in  the  spring 
of  the  year  1836,  and  terminated  in  the  year  1840.    The  whole  of 


402  Institution  of  Civil  Engineers. 

the  tunnels  are  30  feet  in  height  from  the  line  of  rails,  and  30  feet 
in  width  ;  they  are  curved  to  a  radius  of  about  1 20  chains ;  the 
gradient  of  that  part  of  the  line  is  four  feet  per  mile.  The  strata 
through  which  they  were  driven  consisted  generally  of  hard  gray 
sandstone  and  shale,  with  the  gray  and  dun  shiver,  &c. ;  in  a  few 
places  only,  the  new  red  sandstone  and  red  marl  were  traversed. 
Every  precaution  was  taken  for  securing  the  roofs,  by  lining  them 
with  masonry  where  the  nature]  of  the  strata  demanded  it,  and  in 
some  places  invert  arches  were  turned  beneath. 

Driftways  were  driven  before  the  tunnels  were  commenced,  and 
shafts  were  sunk  to  enable  the  work  to  proceed  at  several  points 
simultaneously.  The  modes  of  conducting  the  works  by  these  means 
are  fully  described,  with  all  the  difficulties  that  were  encountered. 
The  construction  of  the  centres  is  given,  with  the  manner  of  lining 
the  arches  with  masonry,  which  is  stated  to  be  what  was  termed 
"  coursed  rubble;"  but  was  of  a  very  superior  description,  and  in 
every  respect  similar  to  ashlar- work. 

The  author  offers  some  remarks  with  regard  to  the  expense  of 
working  tunnels  by  means  of  centre  driftways.  He  states  this  plan 
to  be  costly,  and  in  many  instances  without  corresponding  advan- 
tages, on  account  of  the  difficulty  of  keeping  the  road  clear  for  the 
waggons.  He  recommends  that  when  driftways  are  used  they  should 
be  on  the  lower  side  of  the  dip  of  the  strata,  as  the  excavation  would 
be  facilitated,  and  the  road  would  be  kept  clearer.  In  long  tunnels 
he  has  found  the  cheapest  and  most  expeditious  mode  of  working 
to  be  by  excavating  the  centre  part  from  shafts,  and  both  the  ends 
(together  if  possible)  from  the  extremities  after  the  open  cuttings 
are  made.  The  drawing  accompanying  the  paper  gave  a  longitu- 
dinal section  of  all  the  tunnels,  and  showed  to  an  enlarged  scale 
several  transverse  sections  of  them,  where  the  variations  of  the  strata 
rendered  either  partial  or  entire  lining  necessary. 

In  answer  to  questions  from  Mr.  Vignoles  and  other  members, 
Mr.  Nixon  explained  that  the  extra  number  of  shafts  had  been  re- 
quired in  order  to  enable  the  works  to  be  completed  within  a  given 
time  :  there  had  not  been  any  accidents  during  his  superintendence, 
but  subsequently  one  of  the  shafts  had  collapsed.  The  cost  of 
driving  the  driftways,  the  dimensions  of  which  were  7  feet  wide  by 
8  feet  high,  was  ten  guineas  per  yard  lineal.  He  then  described 
more  fully  his  proposed  plan  of  cutting  the  driftways  on  the  lower 
side,  instead  of  the  centre  of  the  tunnel,  and  stated  the  advantages 
chiefly  to  consist  of  a  saving  in  labour  and  gunpowder,  as  a  small 
charge  sufficed  to  lift  a  considerable  mass  of  rock  when  acting  from 
the  dip  :  the  road  was  also  less  liable  to  be  closed  by  the  materials 
falling  into  it  when  the  enlarged  excavation  proceeded  from  one  side 
instead  of  upon  both  sides. 

Dr.  Buckland,  after  returning  thanks  for  his  election  as  an  hono- 
rary member  of  the  Institution,  expressed  his  gratification  at  the 
prospect  of  a  more  intimate  union  between  engineering  and  geology, 
which  could  not  fail  to  be  mutually  beneficial,  and  cited  examples 
of  this  useful  oo-operation  in  the  cases  of  railway  sections,  and 


Institution  of  Civil  Engineers.  403 

models  that  had  recently  been  furnished  by  engineers  to  the  Museum 
of  (Economic  Geology. 

He  then  proceeded  to  remark  upon  the  geological  features  of  the 
South- Western  Coal-Field  near  Bristol  and  Bath,  which  had  been 
described  by  Mr.  Conybeare  and  himself,  in  the  Transactions  of  the 
Geological  Society  of  London  (1824). 

Some  of  the  tunnels  near  Bristol  are  driven  in  the  Pennant  grit 
of  the  coal  formation,  where  it  is  thrown  up  at  a  considerable  angle, 
and  composed  of  strata  yielding  slabs  and  blocks  of  hard  sandstone 
used  extensively  for  pavement. 

In  traversing  such  inclined  and  dislocated  strata,  the  engineer's 
attention  should,  he  conceived,  be  especially  directed  to  the  original 
joints  that  intersect  the  beds  nearly  at  right  angles  to  their  planes  of 
stratification,  and  also  to  the  fractures  produced  during  the  move- 
ments they  have  undergone.  These  natural  divisions  and  partings 
render  such  inclined  stratified  rocks  unworthy  of  confidence  in  the 
roof  of  any  large  tunnel,  and  liable  to  have  masses  suddenly  de- 
tached. 

Inclined  strata  of  a  similar  sandstone  are  perforated  by  many  tun- 
nels on  the  railway  near  Liege,  in  nearly  all  of  which  the  roofs  are 
supported  by  brick  arches. 

It  has  been  found  impossible  to  make  the  tunnels  through  lias 
and  red  marl  without  continuous  arches  of  masonry. 

In  any  of  the  tunnels  which  have  been  carried  through  strata  of 
the  great  oolite,  the  parts  left  unsupported  by  masonry  would,  in  his 
opinion,  be  peculiarly  liable  to  danger,  because  even  the  most  com- 
pact beds  of  oolite  are  intersected  at  irregular  intervals  by  loose  joints 
at  right  angles  to  the  planes  of  the  strata,  and  occasionally  by  open 
cracks :  and  it  is  to  be  feared  that  the  vibration  caused  by  the  rail- 
way carriages  would  tend  eventually  to  loosen  and  detach  these 
masses  of  stone.  ' 

He  apprehended  still  greater  danger  would  exist  in  tunnels  cut 
through  the  loosely  joined  strata  of  chalk,  unless  they  are  lined 
throughout  with  strong  masonry ;  and  even  that,  in  a  recent  case,  had 
been  burst  through  by  the  weight  of  the  incumbent  loose  chalk 
coming  suddenly  upon  the  arch. 

In  open  cuttings  through  chalk, where  the  numerous  interstices  and 
the  absence  of  alternating  clay-beds  prevent  any  accumulation  of 
water,  there  is  little  chance  of  such  frequent  landslips  as  occur  where 
beds  of  stone,  gravel,  or  sand  rest  on  beds  of  clay ;  but  until  the  side 
walls  of  chalk  are  reduced  to  a  slope  at  which  grass  will  grow,  they 
will  be  subject  to  continual  crumblings  and  the  falling  down  of  small 
fragments,  severed  by  the  continual  expansion  and  contraction  of  the 
chalk,  under  the  destructive  force  of  atmospheric  agents,  and  chiefly 
of  frost. 

In  open  cuttings,  where  the  inclination  of  the  strata  is  towards  the 
line  of  rails,  the  slope  should  be  made  at  a  greater  angle  than  if  the 
strata  incline  from  the  rails ;  if  this  be  done,  fewer  landslips  will 
occur  from  accumulations  of  water  between  the  strata  thus  inclined 
towards  the  rails ;  and  such  sjips  may  be  further  guarded  against  by 


4  04  London  Electrical  Society. 

minute  and  careful  observation  of  the  nature  of  the  individual  strata, 
and  a  scientific  application  of  subterranean  drains  at  the  contact  of 
each  permeable  stratum  with  a  subjacent  bed  of  clay. 

Tunnels  can  be  safely  formed  without  masonry  in  unstratified 
rocks  of  hard  granite,  porphyry,  trap,  &c,  and  in  compact  slate 
rocks  ;  also  in  masses  of  tufa,  such  as  cover  Herculaneum,  and  are 
pierced  by  the  grotto  of  Pausilippo  near  Naples ;  but,  in  his  opinion, 
wide  tunnels  driven  in  stratified  rock  could  not  be  considered  secure 
unless  they  were  supported  by  arches. 

Mr.  Sopwith  confirmed  the  remarks  on  the  importance  to  the 
civil  engineer  of  a  knowledge  of  the  geological  character  of  the  strata 
through  which  tunnels  or  open  cuttings  were  to  be  made  :  the  cost 
was  materially  affected,  as  well  as  the  stability  of  the  works.  The 
angle  of  inclination  and  the  lines  of  cleavage  should  be  carefully 
studied  :  on  one  side  of  a  cutting  the  slope  might  be  left  steep,  and 
all  would  be  firm  and  dry ;  whilst  on  the  other,  if  the  same  slope 
was  adopted,  all  would  appear  disintegrated  and  wet,  and  a  series  of 
accidents  would  be  the  necessary  consequence.  He  could  not  suffi- 
ciently urge  the  importance  of  a  more  intimate  connexion  between 
the  geologist  and  the  engineer. 

LONDON  ELECTRICAL  SOCIETY. 
[Continued  from  p.  313.] 

Oct.  18,  1842. — The  Chairman  announced  that  Walter  Hawkins, 
Esq.,  M.E.S.,  F.Z.S.,  &c,  had  presented  the  Society  with  a  third  spe- 
cimen of  the  Gymnotus  Electricus ;  but  which,  like  the  two  former, 
has  not  survived  the  voyage.  It  is  now  undergoing  dissection,  the  re- 
sult of  which  will  be  laid  before  the  Society.  Mr.  Hawkins  intends 
persevering  until  he  succeeds  in  his  desire  to  present  a  living  speci- 
men to  the  Society. 

A  letter  to  the  Secretary  from  Mr.  Phillips,  M.E.S.,  was  read,  con- 
taining "  the  particulars  of  a  fatal  accident  by  lightning  at  Se-  Blazey ." 
Some  children  had  taken  refuge  from  a  storm  in  a  toll-house,  near 
which  was  an  elevated  crane,  and  also  a  comparatively  lofty  house.  The 
electric  matter  discharged  itself,  not  on  either  of  these  (apparently) 
better  objects,  but  burst  upon  the  low  hut,  and  in  its  passage  to  the 
earth  killed  two  of  the  children,  and  hurt  others.  From  the  draw- 
ing which  accompanied  this  letter,  it  appears  that  the  toll-house  was 
immediately  at  the  edge  of  a  rivulet.  The  lightning  divided  itself 
in  its  passage  down  the  house,  first  entering  by  the  soot  of  the 
chimney.  The  letter  also  contains  an  account  of  the  damage  done 
to  a  ship  at  Par  by  the  same  storm.  The  top-mast  was  shattered  to 
pieces  ;  a  large  piece  was  knocked  out  of  the  lower  part  of  the  main- 
mast ;  the  rupture  occurred  exactly  at  the  termination  of  a  chain 
hanging  from  the  cross-trees,  the  said  chain  having  protected  the 
upper  portion  of  the  same  mast.  Several  men  were  knocked  down. 
The  crew  spoke  of  a  suffocating  smell  of  sulphur. 

A  translation,  by  Mr.  "Walker,  Hon.  Sec,  of  M.  Becquerel's  first 
observation  "  On  the  Electro-Chemical  Properties  of  Simple  Bodies, 
and  on  their  application  to  the  Arts,"  was  then  read.     The  author 


Notices  respecting  New  Books.  405 

speaks  of  electro-chemistry  as  being  "  a  bond  between  physics  and 
chemistry."  He  says,  that  formerly  our  experiments  were  carried 
on  by  large,  but  now  by  small  series  of  Volta's  pairs,  and  thus  are 
our  operations  easier  of  practice.  He  intends  treating  on  all  simple 
bodies,  beginning  with  the  metals,  and  of  those  with  gold.  He  al- 
ludes to  certain  principles  established  in  former  papers,  and  pur- 
poses showing  the  application  of  electro-chemistry  to  the  arts,  as  in 
assaying,  gilding,  &c.  He  dwells  in  his  introduction  upon  the  che- 
mical theory,  and  adduces  two  important  facts  in  confirmation  of  its 
truth  ; — 1st,  that  there  is  no  chemical  action  without  a  considerable 
disengagement  of  electricity ;  2nd,  that  a  Volta's  pile,  charged  with 
a  liquid  not  acting  chemically  on  either  of  the  two  elements  of  which 
each  body  is  composed,  does  not  become  charged,  that  is,  produces 
neither  current  nor  electricity  of  tension.  If  one  of  the  two  ele- 
ments is  attacked,  even  very  feebly,  by  the  liquid,  the  effects  of  cur- 
rent and  those  of  tension  immediately  follow.  As  the  chemical 
action  increases,  so  do  the  electrical  effects.  He  offers  an  observa- 
tion, due  to  his  son  Edward,  which  he  considers  of  much  weight  in 
favour  of  this  theory.  "When  one  substance  acts  on  another,  under 
the  influence  of  light,  electrical  effects  are  produced,  as  in  all  che- 
mical reactions,  which  effects  are  manifested  so  long  as  this  influ- 
ence remains.  If  it  ceases  to  exist,  there  is  no  longer  any  sign  of 
electricity,  and  nevertheless  the  contact  of  the  newly-formed  sub- 
stances with  the  metallic  plates,  still  exists,  and  nothing  is  changed 
in  the  circuit."  He  then  introduces  gold,  its  extraction  from  the 
ore,  and  the  modes  of  assay,  illustrated  by  several  experiments  "of 
his  own  upon  the  ores  of  the  Oural  and  the  Altai,  in  order  to  exa- 
mine the  nature  and  extent  of  the  stamping  and  washing  best  fitted 
to  produce  least  waste.  He  then  adverts  to  amalgamation,  &c,  and 
proceeds  to  the  further  execution  of  his  task,  at  which  point  the 
present  translation  ceases,  the  remaining  portion  being  reserved  for 
a  future  meeting. 

An  abstract  of  observations  on  the  degree  of  identity  between 
electrical  and  chemical  affinity,  by  Mr.  Prater,  M.E.S.,  was  read. 

Mr.  Weekes's  Electro-Meteorological  Journal  for  September  was 
laid  before  the  Society. 


LXX.   Notices  respecting  New  Books. 

The  Difficulties  of  Elementary  Geometry,  especially  those  which  concern 
the  Straight  Line,  the  Plane,  and  the  Theory  of  Parallels.  By 
Francis  William  Newman,  Tutor  at  Manchester  College. 
Longmans. 

THE  philosophy  of  our  mathematical  processes  is  far  from  being 
a  favorite  subject  of  investigation  in  this  country ;  though 
amongst  the  continental  geometers  it  is  cultivated  with  singular 
predilection.  There  are,  however,  two  aspects  under  which  this 
class  of  inquiries  may  be  viewed ;  or  more  properly,  two  distinct 
branches  of  the  inquiry,  which  seem  to  require  faculties  of  a  consi- 
derably dissimilar  kind.     The  first  class  is  that  in  which  the  logical 


406  Notices  respecting  New  Books. 

character  of  the  several  methods  is  examined,  in  connexion  with 
the  phenomena  of  the  human  mind.  The  character  of  our  first  prin- 
ciples, and  the  logic  of  the  early  theorems  of  each  branch  of  pure 
mathematics,  are  proposed  by  this  class  of  philosophers  as  the  im- 
mediate subjects  of  their  investigation.  The  other  class,  and  that  the 
more  influential  and  learned  one,  proposes  to  discover  the  influence 
of  methods  of  research  upon  the  progress  of  discovery,  to  classify 
our  knowledge  according  to  its  bearing  upon  this  one  point,  and  to 
generalize,  as  far  as  possible,  the  isolated  and  incompletely  connected 
propositions  which  are  already  known. 

Of  this  latter  class  M.  Chasles  is  a  splendid  example ;  and  of  the 
former,  Mr.  Newman  is  a  very  respectable  and  (which  renders  it  of 
more  value)  a  very  useful  one. 

The  "  off-handed  "  manner  in  which  the  fundamental  principles 
of  geometry  are  generally  dismissed  by  systematic  writers  on  the 
subject,  is  essential  to  the  general  style  and  objects  with  which  such 
works  are  composed,  namely,  the  most  brief  development  of  the 
greatest  possible  number  of  geometrical  truths  in  a  given  space. 
Still,  we  think  that  the  general  purposes  of  mental  culture  would 
be  better  studied  in  making  geometry  merely  one  of  the  illustrations 
of  the  phenomena  of  mind  :  and  in  this  Mr.  Newman  has  evidently 
entertained  the  same  views  that  we  do,  and  as  was  so  forcibly  urgecj 
by  that  distinguished  master  of  the  philosophy  of  the  human  mind, 
Dugald  Stewart ;  though  perhaps  we  differ  from  each  of  them,  as  they 
do  from  each  other,  on  certain  points  brought  under  discussion. 

In  a  notice  like  the  present,  it  would  be  impossible  to  give  any 
idea  of  the  details  of  the  work.  We  would  moreover  remark,  that  to 
the  discussion  of  the  fundamental  principles  of  the  geometry  of  the 
school  of  Euclid  our  approbation  and  recommendation  is  mainly  con- 
fined. When  the  author  travels  beyond  these  boundaries  he  is  evi- 
dently "  not  at  home,"  as  his  acquaintance  with  the  higher  branches 
of  modern  geometry  is  evidently  very  limited,  and  his  criticisms, 
therefore,  of  little  value.  We  can,  however,  with  this  reservation, 
and  without  pledging  ourselves  to  the  entire  adoption  of  the  author's 
views  and  reasonings,  most  cordially  recommend  the  perusal  of  the 
book  to  the  speculative  geometer,  and  urge  its  careful  study  upon 
those  who  are  engaged  in  teaching  the  elements  of  the  science  for 
the  purpose  of  cultivating  the  faculties,  rather  than  of  "  creating 
mathematicians  by  profession." 

Logarithmic  and  Trigonometric  Tables,  %c.  London :  Simpkin  and 
Marshall,  1836. 
Six  years  ago  a  private  gentleman  residing  in  the  country  caused 
to  be  printed  an  edition  of  Hassler's  Logarithmic  Tables.  By 
various  causes  the  advertisement  of  this  book  was  delayed,  so  that 
up  to  the  present  time  it  has  remained  altogether  unknown,  even  to 
those  who  take  pleasure  in  collecting  and  comparing  tables.  On 
these  facts  coming  to  the  knowledge  of  the  writer  of  this  paragraph, 
he  recommended  that,  considering  the  length  of  time  which  had 
elapsed,  the  work  should  not  be  brought  into  notice  without  some 


Intelligence  and  Miscellaneous  Articles.  407 

re-examination.  In  consequence  of  this  recommendation,  a  well- 
practised  computer  in  the  Nautical  Almanac  Office  was  employed  to 
read  three  thousand  of  the  logarithms  of  numbers  and  eight  degrees 
of  the  trigonometrical  portion  (all  chosen  at  hazard),  and  compare 
them  with  tables  of  undoubted  accuracy.  The  consequence  was,  the 
detection  of  only  three  errors,  one  in  the  numbers,  two  in  the  sines, 
&c. ;  of  these  three  there  was  only  one  which  an  expert  user  of  the 
tables  could  not  have  detected  at  sight.  This  being  considered,  and 
also  the  number  of  errors  which  were  detected  in  Hassler's  book  du- 
ring the  printing,  it  is  certain  that  the  work  before  us  must  be  very 
correct ;  as  correct,  indeed,  as  any  table  is  likely  to  be  unless  it  have 
been  first  stereotyped  and  then  re-examined,  and  much  more  so 
than  most  others  of  the  same  size. 

The  work  is  an  imitation  of  Hassler's,  and  has  the  same  small  oc- 
tavo form.  All  the  logarithms  are  to  seven  decimals.  The  loga- 
rithms of  numbers  are  as  usual :  in  the  trigonometrical  portion  the 
first  and  last  five  degrees  are  to  every  ten  seconds,  all  the  rest  to  every 
half  minute,  with  differences  for  ten  seconds  annexed.  In  the  first  two 
degrees  is  added  a  factor  for  facilitating  the  determination  of  the 
logarithmic  sine  or  tangent  of  the  fractional  part  of  a  second.  The 
type  is  clear  and  the  paper  good.  We  can  decidedly  recommend  the 
work,  and  have  we  think  shown  reasons  for  our  confidence. 

LXXI.   Intelligence  and  Miscellaneous  Articles. 

On  itie  Law  of  Double  Refraction.  By  James  MacCullagh, 
Fellow  of  Trinity  College,  and  Professor  of  Mathematics  in 
the  University  qf  Dublin  *. 
IT  AV1NG  mentioned,  in  an  articlef  which  I  sent  a  few  days 
-*•-*•  ago  for  insertion  in  the  Philosophical  Magazine,  that  I 
had  been  led,  in  following  out  an  hypothesis,  to  a  law  of 
double  refraction  more  general  than  that  of  Fresnel,  I  think 
it  may  be  well  to  state  very  briefly  the  nature  of  that  law,  and 
to  point  out  the  difference  between  it  and  the  law  of  Fresnel, 
especially  as  I  have  since  observed  that  the  difference  is  one 
of  a  very  extraordinary  kind,  and  one  which,  if  it  has  a  real 
existence  (a  question  which  experiment  only  can  decide),  may 
serve  to  account  for  phaenomena  that  have  seemed  hitherto 
inexplicable. 

I  have  said,  in  the  article  referred  to,  that  when  the  poten- 
tial V,  which  is  a  function  of  the  second  degree,  is  supposed 
to  contain  only  the  squares  and  products  of  the  derivatives 
X,  Y,  Z,  X2,  Y2,  Z2,  X4,  &c,  we  get  the  law  of  Fresnel,  as  well 
as  the  law  of  crystalline  dispersion  ;  but  if  we  make  the  more 
general,  and  apparently  the  more  natural  supposition,  that  it 

*  Communicated  by  the  Author. 

+  On  the  Dispersion  of  the  Optic  Axes,  and  of  the  Axes  of  Elasticity,  in 
Biaxal  Crystals.     [Inserted  in  the  last  Number,  p.  293.] 


408    Professor  MacCullagh  on  the  Law  of  Double  Refraction. 

contains  also  the  squares  and  products  of  the  alternate  deriva- 
tives Xj,  Y,,  Z15  X3,  Y3,  Z3,  &c.,  then  we  get,  of  course,  a  dif- 
ferent law.  Now  I  find  that  there  will  still  be  two  optic  axes 
for  each  colour,  and  that  the  two  directions  of  vibration  in  a 
given  wave-plane  will  have  the  same  relation  to  them  as  be- 
fore ;  while  the  difference  of  the  squares  of  the  two  velocities 
of  propagation  will  continue  proportional  to  the  product  of 
the  sines  of  the  angles  which  the  wave  normal  makes  with  the 
optic  axes;  but  the  sum  of  the  squares  of  these  velocities  will 
be  increased  or  diminished  by  a  quantity  proportional  to  the 
square  of  a  perpendicular  let  fall  from  the  centre  on  the  tan- 
gent plane  of  a  certain  very  small  ellipsoid,  this  tangent  plane 
being  supposed  parallel  to  the  wave.  Such  is  the  general  re- 
sult for  biaxal  crystals ;  but  its  bearing  will  be  best  perceived 
by  taking  the  case  of  a  uniaxal  crystal,  wherein  the  law  of 
Fresnel  reduces  itself  to  that  of  Huyghens. 

In  this  case  the  wave-surface  will,  instead  of  the  sphere  and 
spheroid  of  Huyghens,  consist  of  two  ellipsoids  touching  each 
other  at  the  extremities  of  a  common  diameter,  which  coin- 
cides with  the  axis  of  the  crystal;  one  ellipsoid  differing  slightly 
from  a  sphere,  the  other  slightly  from  a  spheroid.  Neither 
of  the  rays  will  be  refracted  according  to  the  ordinary  law, 
nor  will  the  wave-surface  be  symmetrical  round  the  axis.  As 
the  law  of  refraction  is  unsymmetrical,  that  of  reflexion  will 
be  so  likewise,  and  thus  we  may  perhaps  obtain  an  explana- 
tion of  the  extraordinary  phaenomena  observed  by  Sir  David 
Brewster  in  reflexion  at  the  common  surface  of  oil  of  cassia 
and  Iceland  spar. 

It  will  no  doubt  appear  strange  to  call  in  question  the  ac- 
curacy of  the  Huyghenian  law,  which  is  generally  considered 
to  be  established  beyond  dispute  by  the  experiments  of  Wol- 
laston  and  Malus.  But  the  fact  is  that  no  exact  experiments 
have  ever  been  made  on  the  refraction  of  the  ordinary  ray. 
Neither  of  those  philosophers  seems  to  have  entertained  any 
suspicion  that  the  ordinary  law  might  be  inapplicable  to  it ; 
they  both  took  for  granted  that  it  followed  the  law  of  Snellius. 
But  their  results  seem  to  be  quite  consistent  with  the  suppo- 
sition that  the  ordinary  index,  for  rays  passing  in  different 
directions  through  Iceland  spar,  may  vary  in  the  third  place 
of  decimals,  perhaps  even  in  the  second.  The  experiments 
of  Rudberg  throw  no  light  upon  the  question,  for  it  happens, 
oddly  enough,  that  though  he  had  two  prisms  in  every  other 
case,  he  used  only  one  of  Iceland  spar ;  he  could  not  there- 
fore compare  the  velocities  of  rays  passing  in  different  direc- 
tions. On  comparing  his  numbers,  however,  with  those  of 
Wollaston  and  Malus,  there  is,  as  Sir  David  Brewster  has 


Intelligence  and  Miscellaneous  Articles.  409 

observed  (Phil.  Mag.,  S.  3.  vol.  i.  p.  8),  a  "  surprising  discre- 
pancy," so  great  indeed  as  to  be  quite  "alarming."  After  re- 
marking the  difficulty  of  finding  any  explanation  of  it,  Sir 
David  concludes  that  it  must  arise  from  the  different  refrac- 
tive powers  possessed  by  different  specimens.  But  though  this 
cause  must  operate  in  some  degree,  we  cannot  tell  to  what  ex- 
tent it  is  effective,  and  the  discrepancy  may  notwithstanding 
be  occasioned,  in  a  great  measure,  by  a  deviation  from  the 
Huyghenian  law.  The  whole  question  must  therefore  be  re- 
opened, and  the  ordinary  indices  for  the  fixed  lines  of  the 
spectrum  must  be  determined  by  means  of  different  prisms 
cut  out  of  the  same  piece  of  Iceland  spar. 

Whatever  the  result  may  be,  whether  it  shall  confirm  the 
law  of  Huyghens,  or  show  that  another  must  be  substituted 
for  it — it  will  at  least  be  useful  for  science,  by  removing  the 
uncertainty  in  which  the  subject  is  at  present  involved. 
Trinity  College,  Dublin,  Sept.  24,  1842. 


ATOMIC  WEIGHTS  OF  ELEMENTS. 
MM.  Marchand  and  Erdmarm  are  at  present  engaged  in  a  series 
of  researches  which  seem  to  prove  that  Prout's  idea  that  all  atomic 
weights  are  multiples  of  that  of  hydrogen,  is  correct.     They  have 
as  yet  examined  only  the  following  bodies  : — 
Oxygen. .   =  100'     1 


Hydrogen  =     12*5 

Carbon . .   =    75*     6 

Nitrogen    =175*     14 


Calcium  . .  =    250  .  .  .  .  20 

Chlorine  . .  =    450 36 

Silver  ....  =  1250  ....  100 

Lead    =  1300  ....  104 


Extract  from  a  letter  from  Berlin  addressed  to  W.  Francis. 


ON  A  VERY  CURIOUS  FACT  CONNECTED  WITH  PHOTOGRAPHY, 
DISCOVERED  BY  M.  MCSSER  OF  KCSNIGSBERG,  COMMUNICATED 
BY  PROF.BESSEL  TO  SIR  D.  BREWSTER*. 

Sir  D.  Brewster  said,  he  was  requested  to  communicate  an  account 
of  some  remarkable  facts  connected  with  the  theory  of  photography. 
A  new  process  of  producing  photographic  impressions  had  been  disco- 
vered by  Dr.  Moeser  of  Kcenigsberg ;  and  an  account  of  the  discovery 
had  been  brought  to  this  country  by  Prof.  Bessel,  who  received  it  from 
the  discoverer  himself.  The  subject  was  most  important,  and  it  would 
have  been  a  great  misfortune  if  the  Physical  Section  had  separated 
without  being  made  acquainted  with  it.  The  following  were  the 
general  facts  connected  with  it : — A  black  plate  of  horn,  or  agate,  is 
placed  below  a  polished  surface  of  silver,  at  the  distance  of  one-twen- 
tieth of  an  inch,  and  remains  there  for  ten  minutes.     The  surface  of 

*  From  the  Report  of  the  proceedings  of  the  British  Association,  Man- 
chester, June  29, 1 842. — Athenaeum,  No.  770.  See  Dr.  Draper's  letter  on 
the  subject  at  p.  348  of  the  present  Number. 

Phil.  Mag.  S.  3.  Vol.  21.  No.  139.  Nov.  1842.        2  E 


4 10  Intelligence  and  Miscellaneous  Articles. 

the  silver  receives  an  impression  of  the  figure,  writing,  or  crest,  which 
may  be  cut  upon  the  agate,  or  horn.  The  figures,  &c,  do  not  ap- 
pear on  the  silver  at  the  expiration  of  the  ten  minutes,  hut  are  ren- 
dered visible  by  exposing  the  silver  plate  to  vapour,  either  of  amber, 
water,  mercury,  or  any  other  fluid.  He  (Sir  D.  Brewster)  had  heard 
Prof.  Bessel  say,  that  the  vapours  of  different  fluids  were  analogous 
to  the  different  coloured  rays  of  the  spectrum ;  that  the  different 
fluids  had  different  effects,  corresponding  to  those  of  the  spectrum ; 
and  that  they  could,  in  consequence  of  such  correspondence,  produce 
a  red,  blue,  or  violet  colour.  The  image  of  the  camera  obscura  might 
be  projected  on  any  surface, — glass,  silver,  or  the  smooth  leather 
cover  of  a  book, — without  any  previous  preparation ;  and  the  effects 
would  be  the  same  as  those  produced  on  a  silver  plate  covered  with 
iodine. 

This  paper  gave  rise  to  an  animated  conversation,  in  the  course  of 
which  M.  Bessel  said  that  he  had  seen  some  of  the  pictures  taken  by 
this  process,  which  were  nearly,  but  not  quite,  as  good  as  those  ob- 
tained by  Mr.  Talbot's  process. — Sir  D.  Brewster  said,  this  was  the 
germ  of  one  of  the  most  extraordinary  discoveries  of  modern  days ; 
by  it  there  seemed  to  be  some  thermal  effect  which  became  fixed  in 
the  black  substance ;  and  not  only  so,  but  M.  Bessel  informed  him, 
that  different  lights  seemed  to  affect  different  vapours  variously,  so 
that  there  seemed  to  be  something  like  a  power  of  rendering  light 
latent ;  a  circumstance  which,  if  it  turned  out  so,  would  open  up 
very  new  and  curious  conceptions  of  the  physical  nature  of  light : 
on  the  emission  theory,  it  would  be  easy  to  account  for  this ;  on 
the  undulatory  theory,  he  could  not  conceive  how  it  could  be  possi- 
ble.— Prof.  MacCullagh  said,  he  believed  Newton  had  somewhere 
thrown  out  a  suggestion,  that  luminous  particles,  as  they  entered 
into  bodies,  might  be  caught  and  retained,  within  certain  bounds,  by 
continual  attractions. — Sir  D.  Brewster  said,  that  the  experiments 
which  he  had  performed  with  nitrous  gas  seemed  to  strengthen 
some  such  view  as  this,  for,  at  certain  temperatures,  we  had  here 
an  instance  of  a  gaseous  body  as  impervious  to  light  as  a  piece  of 
iron. — Sir  J.  Herschel  thought  it  a  pity  to  encumber  this  new  and 
extensive  field  of  discovery  now  laid  open  to  them  by  any  specula- 
tions connected  with  the  theory  either  of  undulations  or  emissions. 
He  had  found  that  paper  could  be  so  prepared,  as  that  the  impres- 
sions of  some  colours  might  become  permanent  upon  it,  while  others 
were  not ;  and  thus  it  became  possible  to  impress  on  it  coloured 
figures  by  the  action  of  light.  He  exhibited  to  the  Section  a  piece 
of  paper  so  prepared,  which,  at  present,  had  no  form  or  picture  im- 
pressed on  it,  but  which  was  so  prepared,  that,  by  holding  it  in  a 
strong  light,  a  red  picture  would  become  developed  upon  it.  He 
wished  much  he  could  prevail  on  Sir  W.  Hamilton  to  explain  to  the 
Section  a  metaphysical  conception,  which  he  had  disclosed  to  him, 
and  which  seemed  to  him,  though  darkly  he  owned,  to  shadow  forth 
a  possible  explanation  of  many  difficulties. — Sir  W.  Hamilton  said, 
that,  appealed  to  by  Sir  J.  Herschel  in  this  manner,  he  could  not 
avoid  placing  before  the  Section  the  theory  alluded  to,  however  im- 


/     Intelligence  and  Miscellaneous  Articles.  411 

perfect  and  obscure.  He  then  explained  it ;  but  we  regret  our  in- 
ability to  express  it  adequately.  It  appeared  to  depend  on  the  con- 
ception of  points,  absolutely  fixed  in  space,  and  endowed  with  cer- 
tain properties  and  powers  of  transmission,  according  to  determined 
laws. — Prof.  MacCullagh  had  indulged  in  speculations  allied  to,  and, 
as  he  conceived,  involving  this  very  conception  of  Sir  W.  Hamilton, 
and  had  even  followed  out  some  of  its  consequences,  by  reducing  it 
to  a  mathematical  form — the  conception  was  of  double  points,  or 
poles,  transmitting  powers — but  he  had  abandoned  it  as  mere  specu- 
lation.— Sir  D.  Brewster  thought  these  speculations  tended  to  re- 
press experimental  research,  and  to  turn  men's  minds  from  what 
was  solid  to  what  was  fanciful. — Sir  J.  Herschel  considered  that 
there  could  be  no  true  philosophy  without  a  certain  degree  of  bold- 
ness in  guessing ;  and  such  guessing,  or  hypothesis,  was  always  ne- 
cessary in  the  early  stages  of  philosophy,  before  a  theory  has  become 
an  established  certainty;  and  these  bold  guesses,  in  their  proper 
places,  he  conceived,  should  be  encouraged,  and  not  repressed.  Sir 
W.  Hamilton's  conception,  he  thought,  perfectly  clear  in  its  meta- 
physics, and  should  not  be  thrown  overboard  merely  because  it  was 
mataphysical.  '  

USE  OF  IRON  WIRE  FOR  SECONDARY  ELECTRO-MAGNETIC  COILS. 

Mr.  J.  E.  Ashby,  B.A.,  of  University  College,  London,  informs  us 
that  fine  iron  wire  covered  with  cotton  may  be  substituted  for  cop- 
per in  secondary  coils,  with  an  increase  rather  than  diminution  of 
effect,  at  less  than  l-6th  of  the  price,  and  with  a  great  saving  of 
space.  Half  a  pound  of  this  wire  costs  Is.  3d.  and  measures  nearly 
1400  feet. 

With  secondary  coils  so  constructed,  he  has  been  able,  he  states, 
to  make  the  magnetic  spark  pass  through  nearly  l-100th  of  an  inch 
between  two  wires,  as  in  Mr.  Crosse's  experiment ;  and  by  means  of 
a  battery  of  about  four  square  inches  negative  plate  and  a  length 
of  only  1 100  feet  in  the  secondary,  to  excite  a  current  in  the  primary 
coil.  Mr.  Gassiot,  Mr.  Ashby  observes,  used  for  the  same  purpose 
2100  feet  of  copper  wire  and  twenty  large  cells  of  Mr.  Daniell's 
battery.  

NON-CONVERSION  OF  CALOMEL  INTO  SUBLIMATE  BY  THE 
ALKALINE  CHLORIDES. 

We  have  in  our  last  Number  adduced  the  numerous  experiments 
of  M.  Mialhe  on  the  conversion  of  calomel  into  corrosive  sublimate. 
The  following  notice,  denying  such  change,  signed  Lepage,  is  from 
the  Journal  de  Chimie  Medicate  for  September. 

M.  J.  Righini  d'Ollegio,  in  a  notice  relative  to  the  action  of  the 
vapour  of  water  on  calomel  (Jvurnalde  Chimie  Medicate,  Avril  1842), 
gives  the  result  of  an  experiment  which  he  performed  in  order  to 
ascertain  if,  as  had  been  lately  announced,  calomel  is  converted  into 
corrosive  sublimate,  by  the  influence  of  the  alkaline  chlorides,  at  the 
temperature  of  the  human  body.     M.  Lepage  states  that  the  result 

2  E  2 


412  Intelligence  and  Miscellaneous  Articles. 

announced  by  the  Italian  chemist  entirely  corroborates  his  own  nu- 
merous observations  on  the  same  subject ;  and  the  following  he 
states  to  be  the  results  of  his  experiments  : — 

1.  Calomel  which  is  perfectly  free  from  sublimate,  digested  with 
its  own  weight  of  hydrochlorate  of  ammonia,  or  any  other  alkaline 
chloride,  in  distilled  water  at  a  temperature  of  100°  to  104°  Fahr., 
during  24,  36,  or  even  48  hours,  underwent  no  change  of  colour. 
The  faltered  liquor  did  not,  by  means  of  any  reagent,  appear  to  con- 
tain a  trace  of  a  mercurial  salt. 

Some  pigeons  which  were  made  to  drink  of  this  same  liquor  for 
several  successive  days  suffered  no  inconvenience  :  the  calomel  lost 
no  sensible  weight. 

2.  The  same  mixture  exposed  to  a  temperature  of  122°  to  140° 
Fahr.,  yielded  a  liquor  which  acted  precisely  in  the  same  way  with 
reagents  and  on  the  animal  ceconomy  as  the  foregoing. 

3.  By  continued  boiling,  however,  and  under  the  influence  of  a 
great  excess  of  chloride,  the  conversion  took  place,  but  only  parti- 
ally.— Journal  de  Chimie  Medicate,  Septembre  1842. 

METHOD   OF   DISTINGUISHING   ZINC   FROM  MANGANESE   IN  SO- 
LUTIONS CONTAINING  AMMONIACAL  SALTS.     BY  M.  OTTO. 

If  solutions  of  chloride  of  zinc  and  chloride  of  manganese,  con- 
taining much  hydrochlorate  of  ammonia,  be  rendered  alkaline  by  so- 
lution of  ammonia,  the  addition  of  the  smallest  quantity  of  solution 
of  hydrosulphuric  acid  precipitates  white  hydrated  sulphuret  of  zinc, 
whilst  no  effect  is  produced  by  it  in  the  solution  of  manganese, 
more  being  required  to  obtain  a  precipitate  of  the  sulphuret  of  the 
latter  metal.  If  acetic  acid  be  then  added  to  the  solutions,  the  sul- 
phuret of  manganese  dissolves  very  readily,  whilst  that  of  zinc  re- 
mains undissolved.  M.  Otto  advises  the  use  of  hydrosulphuric  acid 
and  not  hydrosulphate  of  ammonia,  because  the  latter,  always  con- 
taining persulphuret,  may  occasion  mistakes,  since  acetic  acid  sepa- 
rates sulphur  from  it.  if,  for  example,  it  be  required  to  determine 
whether  iron  filings  contain  brass,  they  are  to  be  dissolved  in  aqua 
regia,  the  peroxide  of  iron  is  to  be  precipitated  by  ammonia,  the 
liquor  is  then  to  be  acidulated,  the  copper  precipitated  by  hydrosul- 
phuric acid,  and  ammonia  is  then  to  be  added  to  the  filtered  liquor, 
which  usually  still  contains  a  sufficient  quantity  of  hydrosulphuric 
acid.  If  a  white  precipitate  be  formed  which  does  not  dissolve  in 
acetic  acid,  it  shows  that  zinc  is  present.  M.  Wackenroder  has 
especially  recommended  the  solubility  of  sulphuret  of  manganese  in 
acetic  acid,  to  separate  manganese  from  other  metals. — Journal  de 
I'harm.  et  deChem.,  Sept.  1842. 


ON  MM.  VARRENTRAPP  AND  WILL  8  METHOD  OF  DETERMINING 
AZOTE  IN  ORGANIC  ANALYSES.    BY  M.  REIZET. 
M.  Reizet  has  submitted  to  examination  the  new  process  recom- 
mended by  MM.  Varrentrapp  and  Will,  for  determining  the  azote  in 
organic  substances.     This  process  is  based  on  the  general  law  of  the 


Intelligence  and  Miscellaneous  Articles.  4-13 

decomposition  of  animal  substances,  by  the  hydrated  fixed  alkalies, 
into  water,  carbonic  acid  and  ammonia,  if  they  contain  azote.  It 
results  from  the  experiments  of  M.  Reizet,  that  this  process  is  not 
entirely  free  from  all  chances  of  error.  In  the  first  place  the  mix- 
ture of  soda  and  lime  retains  atmospheric  air  confined  in  a  peculiar 
state  of  condensation  ;  this  air  cannot  be  expelled  either  by  a  cur- 
rent of  gas,  nor  under  the  influence  of  a  vacuum.  During  combus- 
tion, the  azote  of  this  air  gives  rise  to  ammonia,  which  is  added  to 
that  coming  from  the  substance  submitted  to  analysis.  Faraday  has 
observed  that  non-azotized  organic  substances,  even  charcoal  and  the 
metals  which  decompose  water,  yield  ammonia  when  calcined  with 
potash  in  contact  with  air. 

Another  chance  of  error  in  the  process  of  MM.  Varrentrapp  and 
Will  results  from  the  circumstance,  that  the  alcohol  in  which  the 
perchloride  of  platina  is  dissolved,  reduces  this  salt  to  the  state  of 
insoluble  protochloride ;  this  operation  takes  place  very  slowly,  it  is 
true,  but  it  is  so  considerable  that  the  protochloride  formed,  mixing 
with  an  ammoniacal  salt  of  platina,  adds  to  its  weight,  and  conse- 
quently sensibly  increases  the  proportion  of  azote.  It  is  not  ex- 
plained how  MM.  Varrentrapp  and  Will  always  obtained  less  azote 
than  indicated  by  theory  in  the  substances  which  they  analysed,  since 
the  causes  of  error  in  their  process  tend  to  give  an  excess,  unless  du- 
ring the  operation  azote  is  disengaged  either  in  a  free  state,  or  in 
some  other  form  than  of  ammonia,  or  that  this  gas  is  not  entirely 
condensed. — Ibid.  

NEW   DOUBLE  SALT  OF   SODA   AND  PROTOXIDE  OF  PLATINA. 

MM.  Litton  and  Schnedermann,  endeavouring  to  discover  an  easy 
and  certain  method  of  preparing  the  double  cyanides  of  platina,  passed 
a  current  of  sulphurous  acid  gas  to  perfect  saturation  through  a  solu- 
tion of  chloride  of  platina,  and  afterwards  saturated  the  liquor  with  car- 
bonate of  soda.  They  thus  obtained  a  very  bulky  precipitate,  which 
was  nearly  colourless,  and  this,  after  perfectly  washing  it,  they  submit- 
ted to  an  attentive  examination  ;  and  they  found  it  to  be  a  double  salt 
of  soda  and  protoxide  of  platina.  When  dry,  this  salt  is  a  white  powder. 
It  is  very  slightly  soluble  in  water,  and  insoluble  in  alcohol.  The  usual 
reagents  do  not  at  all  indicate  the  presence  of  platina  in  the  aqueous 
solution.  If  hydrosulphuric  acid  be  passed  into  it,  or  if  it  be  mixed 
with  hydrosulphate  of  ammonia,  it  does  not  change  even  after  a  long 
time  has  elapsed,  or  by  increase  of  temperature  ;  but  if  there  be 
added  at  the  same  time  an  acid  which  decomposes  the  salt,  the  li- 
quor becomes  slowly  coloured  at  common  temperatures,  and  when 
heated  it  soon  becomes  reddish-brown ;  and  afterwards  sulphuret  of 
platina  separates.  The  alkalies,  do  not  decompose  this  salt;  when 
heated  with  potash  or  soda,  it  undergoes  no  sensible  change. 
Treated  in  a  dry  state  with  a  solution  of  hydrosulphate  of  ammonia, 
or  of  sulphuret  of  potassium,  it  suffers  no  change  at  common  tem- 
peratures, but  by  ebullition  it  becomes  gradually  coloured,  is  even- 
tually completely  dissolved  ;  and  from  this  solution  sulphuret  of  pla- 
tina is  precipitated  by  acids. 


414  Intelligence  and  Miscellaneous  Articles. 


'b 


Even  diluted  acids  readily  dissolve  this  salt,  decomposing  it  and 
evolving  sulphurous  acid.  The  solution  in  hydrochloric  acid  yields 
crystals  of  chloride  of  sodium  by  evaporation,  and  by  the  addition 
of  ammonia  a  green  crystalline  precipitate  of  ammonio-chloride  of 
platina.  The  solution  in  sulphuric  acid  yields,  after  the  requisite 
evaporation,  crystals  of  sulphate  of  soda,  and  assumes  the  deep  colour 
well  known  to  be  owing  to  the  protosulphate  of  platina.  At  a  cer- 
tain degree  of  concentration,  metallic  platina  separates,  a  property 
which  is  well  known  to  belong  also  to  the  protosulphate  of  platina 
prepared  by  direct  combination. 

The  solution  in  nitric  acid  when  evaparated  by  heat  has  a  deep 
reddish-brown  colour ;  if  to  this  hydrochlorate  of  ammonia  be  added 
no  precipitate  is  formed,  but  if  the  solution  be  evaporated  with  the 
hydrochlorate  of  ammonia  almost  to  dryness,  and  water  be  added  to 
the  residue,  there  remains  a  great  quantity  of  ammonio-chloride  of 
platina,  which  does  not  dissolve.  It  appears  that  the  reddish-brown 
colour  is  owing  to  the  formation  of  sulphate  of  platina,  a  salt,  which, 
as  observed  by  Mr.  E.  Davy,  is  not  decomposed  by  hydrochlorate  of 
ammonia,  unless  they  be  evaporated  together  to  dryness. 

The  double  salt  in  question  dissolves  readily  in  an  aqueous  solu- 
tion of  cyanide  of  potassium,  and  by  evaporating  the  solution,  acicu- 
lar  crystals  of  cyanide  of  potassium  and  platina  separate.  If  this 
salt  be  exposed  to  a  temperature  of  356°  to  392°  Fahr.,  it  loses  its 
water  completely ;  ■  and  when  heated  to  464°  Fahr.  it  undergoes  no 
further  alteration ;  but  if  the  temperature  be  raised  still  higher,  it 
begins  to  suffer  slight  decomposition,  its  colour  becoming  deeper. 
It  requires,  however,  a  continued  red  heat  for  its  complete  decompo- 
sition, and  there  then  remains  a  mixture  of  sulphate  and  sulphite 
of/soda  with  metallic  platina.  The  formula  of  this  anhydrous  salt  is 
3  NaO,  S024-Pt  O,  SO,  and  that  of  the  hydrated  salt  2  (3  Na  O, 
S02+Pt02)  +  3H20*.-/W. 

COMPOSITION  OF  CONIA. 

According  to  M.  V.  Ortigosa,  conia  when  completely  anhydrous 
consists  of 

32  equiv.  of  Hydrogen 199*67  12*55 

16      ...         Carbon 1213-60  76'31 

2      ...  Azote    177-04  11-14 

Equivalents 159031  100- 

Pure  conia  distils  without  any  residue,  but  if  it  contains  water,  a 
resinous  matter  is  left;  its  boiling-point  is  413°  Fahr. 

Conia  is  a  powerful  base  ;  like  ammonia  it  gives  a  precipitate  with 
the  proto- salts  of  tin  and  of  mercury,  and  with  the  persalts  of  iron 
it  appears  even  to  expel  ammonia  from  its  compounds.  It  reduces 
the  salts  of  silver,  gives  with  sulphate  of  copper  a  precipitate  slightly 
soluble  in  water,  and  very  soluble  in  alcohol  and  aether. 

The  precipitate  obtained  by  mixing  a  solution  of  bichloride  of  mer- 
*  M.  Liebig  had  previously  obtained  a  double  sulphite  of  ammonia  and 

Krotoxide  of  platina  composed  according  to  the  formula  2  S  O3,  PtO, 
f2  H6.— Chitnie  Organiqtte  de  Liebig.  Paris,  1840,  p.  102. 


Meteorological  Observations.  415 

cury  with  conia  is  insoluble  in  water,  alcohol  or  sether ;  the  compound 
is  white, pulverulent,  and  decomposes  at  21 2°  Fahr.,  becoming  yellow. 
If  to  an  aqueous  solution  of  conia  one  of  sulphate  of  alumina  be 
added,  crystals  are  gradually  formed,  which  with  the  microscope  are 
easily  seen  to  be  octohedrons.  These  crystals,  when  they  have  been 
carefully  washed,  blacken  if  heated  on  platina  foil. — Ibid. 


mr.  luke  Howard's  cycle  of  eighteen  years  in  the 

seasons  of  britain. 
The  readers  of  the  Philosophical  Magazine  will  doubtless  learn 
with  pleasure  that  the  cycle  shows  well  this  year  to  the  end  of  Sep- 
tember, viz. — 

1842.  Nine  months  rain    17'35  inch. 

1824.  The  same     18-68  inch. 

So  that  we  are   1*33  inch. 

(only)  in  arrear  for  rain. 

1842.  Average  temperature  of  nine  months 50" 86° 

1824.  The  same 49*95 

So  that  we  appear  to  have  of  heat  in  advance    .  .      O^l0 
The  Villa,  Ackworth,  Sept.  7,  1842.  Luke  Howard. 


METEOROLOGICAL  OBSERVATIONS  FOR  SEPTEMBER  1842. 
Chiswick. — September  1.  Constant  rain  :  temperature  increasing  towards  night. 
2.  Overcast :  sultry.  3.  Overcast :  clear.  4.  Cloudy  and  fine.  5.  Foggy  :  very 
fine.  6.  Very  fine :  clear.  7.  Slight  fog  :  fine.  7 — 10.  p.m.  violent  thunder- 
storm, much  sheet-  and  sometimes  forked  lightning  :  heavy  rain,  with  some  hail : 
clear  at  night.  8.  Boisterous,  with  heavy  rain.  9.  Rain  :  cloudy.  10.  Show- 
ery. 11  —  15.  Very  fine.  16.  Foggy  :  fine.  17-  Cloudy:  rain.  18.  Fine,  with 
slight  haze  :  rain.  19.  Cloudy  :  showers.  20.  Showery.  21.  Cloudy  and  fine  : 
clear.  22.  Foggy :  cloudy  and  fine  :  slight  rain.  23.  Overcast :  heavy  rain. 
24.  Rain  :  overcast.  25.  Slight  showers  :  stormy,  with  rain  at  night.  26.  Heavy 
clouds  and  showers :  clear.  27.  Overcast :  stormy  and  wet.  28.  Fine.  29. 
Clear  :  boisterous,  with  rain.  30.  Clear  and  fine  :  slight  rain.  Mean  tempera- 
ture of  the  month  0*47°  above  the  average. 

Boston. — Sept.  1.  Cloudy  :  rain  early  a.m.  2 — 5.  Fine.  6.  Cloudy.  7.  Fine: 
rain, with  thunder  and  lightning  at  night.  8.  Cloudy.  9.  Cloudy:  rain  early  a.m.  : 
rain  p.m.  10.  Cloudy  :  rain  early  a.m.  :  rain  p.m.,  with  thunder  and  lightning. 
11.  Cloudy.  12.  Cloudy:  rain  early  a.m.  13.  Fine.  14—16.  Cloudy.  17. 
Fine:  rain  p.m.  18,  19.  Cloudy:  rain  early  a.m.  20.  Fine.  21  Cloudy. 
22.  Rain.  23.  Rain  :  rain  early  a.m.  :  rain  p.m.  24.  Fine.  25.  Cloudy  :  rain 
early  a.m.  26,  27.  Cloudy.  28.  Stormy  :  rain  early  a.m.  29.  Rain  and  stormy : 
rain  early  a.m.     30.   Cloudy:  rain  early  a.m. 

Sandwich  Manse,  Orkney. — Sept.  1 — 3.  Showers.  4.  Showers:  cloudy.  5. 
Bright:  rain.  6.  Rain  :  clear.  7.  Damp:  cloudy.  8.  Rain.  9.  Cloudy: 
rain.  10.  Clear :  aurora.  11.  Bright :  fog.  12.  Bright :  cloudy.  13.  Drizzle  : 
cloudy.  14,  15.  Bright:  cloudy.  16.  Cloudy:  drops.  17.  Cloudy  :  clear. 
18.  Bright:  clear.  19.  Cloudy:  rain.  20.  Cloudy.  21.  Rain:  clear.  22. 
Rain :  drizzle.  23.  Damp  :  dri/zle.  .  24.  Cloudy.  25.  Bright :  cloudy.  26. 
Cloudy:  showers.  27.  Bright :  cloudy.  28,29.  Cloudy:  clear.  30.  Cloudy. 
Applegarth  Manse,  Dumfries-shire. — Sept.  1.  Very  wet  morning.  2.  Fair  but 
cloudy.  3.  Rain  p.m.  4.  Fine  and  fair.  5.  Thick  :  rain  p.m.  6.  Fair  but 
cloudy.  7.  Fair  and  fine.  S.  Heavy  rain  early  a.m.  14.  Cloudy  and  moist. 
15,  16.  Fair  but  cloudy.  17.  Rain  a.m.  18.  Fair  and  fine  :  lightning.  19. 
Fair  and  fine  :  thunder.  20.  Fair  and  fine.  21.  Fair  and  fine  :  thunder.  22. 
Fair  and  fine  till  p.m.  :  rain.  23.  Rain  early  a.m.  24.  Rain.  25 — 28.  Fair 
and  cool.     29.  Fair  and  cool :  a  few  drops.     30.  Fair  and  cool. 


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THE 
LONDON,  EDINBURGH  and  DUBLIN 

PHILOSOPHICAL  MAGAZINE 

AND 

JOURNAL  OF  SCIENCE. 


[THIRD  SERIES.] 


DECEMBER   1842. 


LXXIL  On  a  Gaseous  Voltaic  Battery.  By  W.  R.  Grove, 
Esq.,  M.A.,  F.R.S.,  Professor  of  Experimental  Philosophy 
in  the  London  Institution. 

To  R.  Phillips,  Esq.,  F.R.S. 
My  dear  Sir, 

IN  the  Philosophical  Magazine  for  February  1839  I  have 
given  an  account  of  an  experiment  in  which  a  galvanometer 
was  permanently  deflected  when  connected  with  two  strips  of 
platina  covered  by  tubes  containing  oxygen  and  hydrogen. 
At  the  conclusion  of  my  notice,  I  say,  "  I  hope,  by  repeating 
this  experiment  in  series,  to  effect  decomposition  of  water  by 
means  of  its  composition."  The  next  paper  of  mine  published 
in  the  same  year  contains  an  account  of  a  battery  to  which  the 
public  has  since  attached  my  name,  and  which  led  me  into  a 
different  field  of  research. 

In  reading  over  my  papers  lately  for  a  purpose  alluded  to 
in  my  letter  of  last  month,  I  was  struck  with  the  above  sentence. 
My  impression  was,  that  I  had  expressed  a  hope  not  very  likely 
to  be  realized ;  but  after  a  few  days'  consideration  I  saw  my 
way  more  clearly,  and  determined  to  try  the  experiment. 

As  the  chemical  or  catalytic  action  in  the  experiment  de- 
tailed in  that  paper,  could  only  be  supposed  to  take  place, 
with  ordinary  platina  foil,  at  the  line  or  water-mark  where  the 
liquid,  gas  and  platina  met,  the  chief  difficulty  was  to  ob- 
tain anything  like  a  notable  surface  of  action.  To  effect  this 
my  first  thought  was  to  surround  the  platina  foil  with  spongy 
platina  precipitated  in  the  usual  way  by  muriate  of  ammonia. 
This  was  suggested  to  me  by  the  known  action  of  spongy  platina 
on  mixed  gas,  which  would  by  its  capillary  attraction  expose  a 
considerable  surface  of  metal  and  liquid  to  the  action  of  the 

Phil.  Mag.  S.  3.  Vol.  21.  No.  140.  Dec.  1842.       2  F 


418      Professor  Grove  on  a  Gaseous  Voltaic  Battery. 

gases.  I  still  think  this  would  be  the  best  mode  of  effecting 
the  object ;  but  as  it  was  very  troublesome  in  manipulation, 
I  determined  to  try  the  platina  platinized  by  voltaic  depo- 
sition from  the  chloride,  as  proposed  for  a  different  purpose 
by  Mr.  Smee.  I  therefore  caused  a  series  of  fifty  pairs  to  be 
constructed,  the  form  and  arrangement  of  which  is  given  in 
the  annexed  figure,  where  ox  denotes  a  tube  filled  with  oxy- 
gen ;  hy  one  filled  with  hydrogen,  and  the  dark  line  in  the 


ow  it, 


axis  of  the  tube  platinized  platina  foil,  which  in  the  battery 
I  constructed  was  about  one-fourth  of  an  inch  wide.  It  is  ob- 
vious that,  by  allowing  the  platina  to  touch  the  liquid,  the  latter 
would  spread  over  its  surface  by  capillary  action  and  expose 
an  extended  superficies  to  the  gaseous  atmosphere.  The  bat- 
tery was  charged  with  dilute  sulphuric  acid,  sp.  gr.  1*2,  and 
the  following  effects  were  produced  : — 

1st.  A  shock  was  given  which  could  be  felt  by  five  persons 
joining  hands,  and  which  when  taken  by  a  single  person  was 
painful. 

2nd.  The  needle  of  a  galvanometer  was  whirled  round  and 
stood  at  about  60° ;  with  one  person  interposed  in  the  circuit 
it  stood  at  40°,  and  was  slightly  deflected  when  two  were  in- 
terposed. 

3rd.  A  brilliant  spark  visible  in  broad  daylight  was  given 
between  charcoal  points. 

4th.  Iodide  of  potassium,  hydrochloric  acid,  and  water 
acidulated  with  sulphuric  acid  were  severally  decomposed ; 
the  gas  from  the  decomposed  water  was  eliminated  in  sufficient 
quantity  to  be  collected  and  detonated.  The  gases  were  evolved 
in  the  direction  denoted  in  the  figure,  i.  e.  as  the  chemical 
theory  and  experience  would  indicate,  the  hydrogen  travelling 


Professor  Grove  on  a  Gaseous  Voltaic  Battery.        419 

in  one  direction  throughout  the  circuit,  and  the  oxygen  in  the 
reverse.  It  was  found  that  26  pairs  were  the  smallest  num- 
ber which  would  decompose  water,  but  that  four  pairs  would 
decompose  iodide  of  potassium. 

5th.  A  gold  leaf  electroscope  was  notably  affected. 
6th.  The  battery  was  charged  with  distilled  water;  the  elec- 
troscope was  affected,  and  iodide  of  potassium  decomposed. 

7th.  Although  the  phenomena  were  too  marked  to  render 
it  in  the  least  probable  that  accidental  circumstances  could 
have  produced  the  current,  still  counter  experiments  were  care- 
fully gone  through ;  thus  the  gases  were  repeatedly  changed, 
oxygen  being  placed  in  the  tubes  which  had  contained  hydro- 
gen, and  vice  versa.  The  effects  were  equally  powerful,  and 
the  direction  of  the  current  was  reversed. 

8th.  All  the  tubes  were  charged  with  atmospheric  air;  no 
effect  was  produced. 

9th.  The  battery  was  charged  with  carbonic  acid  and  nitro- 
gen in  the  alternate  tubes ;  not  the  slightest  effect  observable. 

10th.  It  was  charged  with  oxygen  and  nitrogen;  not  any 
effect. 

11th.  With  hydrogen  and  nitrogen,  slight  effects.  The 
difference  between  this  and  the  last  experiment  at  first  struck 
me  as  extraoi'dinary,  but  upon  consideration  was  easily  ex- 
plicable. The  liquid  being  exposed  to  the  air  would  neces- 
sarily absorb  some  oxygen,  and  this  with  hydrogen  would  give 
rise  to  a  current.  This  was  proved  by  the  liquid  rising  in  the 
hydrogen  tubes,  but  not  in  those  containing  nitrogen ;  and, 
as  a  further  proof,  one  set  of  tubes  was  charged  with  hydro- 
gen, and  the  alternate  set  with  acidulated  water  without  gas  ; 
a  slight  current  was  perceptible :  with  oxygen  and  the  liquid 
in  alternate  tubes  there  were  no  effects  produced. 

12th.  As  the  oxygen  and  hydrogen  were  procured  in  the 
first  instance  by  electrolysis,  and  as  Dr.  Schcenbein  in  his 
careful  experiments  on  polarized  electrodes  supposed  the  pe- 
culiar substance  which  he  has  named  Ozone  to  be  a  principal 
agent,  I  caused  the  tubes  to  be  charged  with  oxygen  evolved 
from  chlorate  of  potash  and  oxide  of  manganese,  and  hydro- 
gen from  zinc  and  sulphuric  acid ;  the  effects  were  the  same. 

The  tubes  were  not  all  of  equal  size,  nor  were  they  gra- 
duated ;  the  exact  proportional  diminution  of  gas  in  each  tube 
could  not  be  ascertained  with  perfect  accuracy ;  both  gases  did 
diminish,  and  the  hydrogen  so  much  more  rapidly  than  the  oxy- 
gen, that  my  assistant,  who  was  unacquainted  with  the  rationale 
of  the  battery,  observed  that  the  hydrogen  was  absorbed  twice 
as  fast  as  the  oxygen.  Mr.  Gassiot  is  now  preparing  a  gra- 
duated battery  of  this  sort,  by  which  the  point  will  be  accurately 

2F2 


420      Professor  Grove  on  a  Gaseous  Voltaic  Battery. 

determined;  supposing  the  gases  at  the  electrodes  and  at  the 
plates  exposed  to  uniform  facilities  of  solution,  the  quantity 
evolved  should  be  equal  to  that  absorbed. 

Several  curious  points  are  suggested  by  this  novel  battery. 

«.  How  is  its  action  explicable  on  the  contact  theory  ?  I 
am  by  no  means  wedded  to  any  theory,  and  have  constantly 
endeavoured  to  look  with  the  eye  of  a  contact  theorist  upon  the 
facts  of  voltaic  electricity,  but  I  cannot  see  them  in  that  light ; 
if  there  be  any  truth  in  the  contact  theory,  I  either  misunder- 
stand it,  or  my  mind  is  unconsciously  biassed.  Where  is  the 
contact  in  this  experiment,  if  not  everywhere  ?  Is  it  at  the 
points  of  junction  of  the  liquid,  gas,  and  platina?  If  so  it  is 
there  that  the  chemical  action  takes  place ;  and  as  contact  is 
always  necessary  for  chemical  action,  all  chemistry  may  be 
referred  to  contact,  or  upon  the  theory  of  an  universal  plenum, 
all  natural  phaenomena  may  be  referred  to  it.  Contact  may 
be  necessary,  but  how  can  it  stand  in  the  relation  of  a  cause, 
or  of  a  force? 

|3.  Its  phaenomena  present  to  my  mind  a  resolution  of  cataly- 
sis into  voltaic  force,  in  other  words,  the  action  of  this  battery 
bears  the  same  relation  to  the  phaenomena  of  catalysis  as  that 
of  the  ordinary  batteries  does  to  those  of  ordinary  chemistry. 
Whether  these  effects  could  be  produced  by  other  inoxidable 
metals  (such  as  gold  or  silver)  is  an  experiment  worth  trying. 
The  more  we  examine  chemical  and  voltaic  actions,  the  more 
closely  do  we  assimilate  them.  For  some  mysterious  reason 
three  elements  seem  necessary  for  very  many  if  not  for  all 
chemical  actions. 

y.  This  battery  is  peculiar  in  having  the  current  generated 
by  gases,  and  by  synthesis  of  an  equal  but  opposite  kind  at 
both  anode  and  cathode;  it  is  therefore,  theoretically,  more 
perfect  than  any  other  form,  as  the  batteries  at  present  known, 
act  by  one  affinity  at  the  anode,  and  have  to  overcome  an- 
other at  the  cathode. 

8.  This  battery  establishes  that  gases  in  combining  and  ac- 
quiring a  liquid  form  evolve  sufficient  force  to  decompose  a 
similar  liquid  and  cause  it  to  acquire  a  gaseous  form.  This 
is  to  my  mind  the  most  interesting  effect  of  the  battery ;  it  ex- 
hibits such  a  beautiful  instance  of  the  correlation  of  natural 
forces. 

Many  other  notions  crowd  upon  my  mind,  but  I  have  oc- 
cupied sufficient  space  and  must  leave  them  for  the  present, 
hoping  that  other  experimenters  will  think  the  subject  worth 
pursuing.  I  remain,  my  dear  Sir,  yours  very  sincerely, 

London  Institution,  Oct.  29, 1842.  W.  R.  Grove. 


[     421     ] 

LXXIII.  On  the  Constant  Voltaic  Battery.  By  J.  F.  Danieia, 

Esq.,  For.  Sec.  U.S.,  Prof.  Chem.  in  King's  College,  London ; 
in  a  Letter  addressed  to  R.  Phillips,  Esq.,  F.R.S.,  Sj-c. 

My  dear  Sir, 

IT  appears  from  Professor  Grove's  letter,  published  in  the 
last  Number  of  the  Philosophical  Magazine,  that  I  was 
under  a  misconception  in  supposing  that  he  had  derived  his 
battery  from  principles  announced  by  me ;  and  that  my  me- 
mory was  treacherous  in  suggesting  that  I  had  heard  him,  at 
a  very  crowded  meeting  of  the  members  of  the  London  Insti- 
tution, admit  (with  a  compliment  which  was  impressive,  but 
doubtless  much  greater  than  the  occasion  required)  that  it 
was  in  following  up  my  train  of  reasoning  that  he  was  led  to 
the  construction  of  the  instrument  whose  wonderful  powers 
he  was  then  about  to  illustrate.     But  waving  this  point  of  re- 
collection, the  error  is  certainly  excusable,  inasmuch  as  the 
nitric  acid  battery  exactly  resembles  the  constant  battery  in 
every  particular  except  the  substitution  of  platinum  and  ni- 
tric acid  for  copper  and  sulphate  of  copper ;  and  an  experi- 
mentalist might,  very  obviously,  have  been  led  to  the  change 
by  following  up  the  principle  of  diminishing  contrary  elec- 
tromotive powers  and  resistances  to  a  current  originating  with 
the  zinc.     Professor  Grove,  however,   states   (although   he 
"  cannot  at  this  distance  of  time  well  describe  what  effect  my 
experiments  had  upon  his  mind ")  that  he  cannot  acquiesce 
in  the  assertion  that  he  was  so  guided ;  but  that  the  idea 
which  immediately  led  to  the  construction  of  his  battery  is 
distinctly  stated  in  the  Phil.  Mag.  for  1839.     The  experiment 
referred  to,  with  two  strips  of  gold  leaf  in  nitric  and  hydro- 
chloric acids,  separated  by  a  porous  diaphragm,  showing  that 
upon  contact  of  the  two  strips  the  gold  in  the  hydrochloric  acid 
was  dissolved,  is  certainly  a  most  beautiful  one ;  but  the  origin 
of  the  force  must  be  admitted  to  be  at  the  junction  of  the  two 
acids;    which,    when  a  path  for  its  circulation    is    opened, 
react  upon  one  another,  and  transfer  by  their  polarization 
chlorine  to  one  electrode,  and  hydrogen  to  the  other;  the 
former  being  taken  up  by  the  gold,  and  the  latter  by  the  nitric 
acid.     What  this  has  to  do  with  the  nitric  acid  battery,  in 
which  the  two  acids  in  contact  are  the  nitric  and  sulphuric, 
I  really  cannot  perceive.     The  origin  of  the  force  in  this  case 
has  always  appeared  to  me  to  be  the  action  of  the  zinc  upon 
the  dilute  sulphuric  acid,  but  Professor  Grove  may  possibly 
consider  it  to  be  still  the  contact  of  the  two  acids.     He  has, 
however,  stated  that  he  was  so  led  to  the  construction  of  his 
battery,  and  X  can  have  nothing  more  to  say  upon  the  subject. 


422         The  Rev.  Professor  Kelland's  Explanation. 

It  is  singular  enough  that  M.  E.  Becquerel's  claim  for  his 
father's  priority  in  the  discovery  of  the  principles  upon  which 
my  battery  is  constructed  appears  from  his  reply  (also  pub- 
lished in  the  last  Number  of  the  Phil.  Mag.)  to  be  founded 
principally  upon  a  similar  supposed  generation  of  force  at  the 
contact  of  the  two  liquids. 

If  this  be  its  true  origin,  I  at  once  allow  that  there  is  some 
foundation  for  the  reclamation ;  but  at  the  same  time  I  must 
repeat  that  such  an  idea  never  occurred  to  me ;  as  will  be 
evident  to  those  who  will  take  the  trouble  to  consult  my  con- 
secutive papers  in  the  Philosophical  Transactions:  and  I 
must  in  that  case  be  content  with  the  somewhat  mortifying 
reflection  that  I  was  led  to  a  right  result  by  wrong  principles. 

The  matter  is,  however,  now  fairly  before  the  scientific 
community,  and  having  corrected  M.  Becquerel's  inadvertent 
remark  about  the  priority  of  Professor  Grove's  experiments, 
I  will  promise  you  to  take  up  no  more  of  your  valuable  space 
with  the  subject.  I  remain,  dear  Sir,  very  truly  yours, 

Kings  College,  Nov.  2,  1842.  J.  F.  Daniell. 

To  R.  Phillips,  Esq.,  fyc.  $?c. 

LXXI V.  On  certain  Arguments  adduced  in  the  last  Number  of 
the  Philosophical  Magazine.     By  the  Rev.  P.  Kelland, 
M.A.,  F.R.SS.  L.  $E.,  F.C.P.S.,  ##.,  Professor  of  Mathe- 
matics in  the  University  of  Edinburgh,  late  Fellow  and  Tutor 
of  Queen's  College,  Cambridge. 

To  Richard  Taylor,  Esq. 
My  dear  Sir, 

THE  Philosophical  Magazine  has  this  moment  reached 
me,  by  which  I  am  sorry  to  see  that  a  misprint,  or  rather 
a  mis-transcription  of  my  paper  in  the  6th  volume  of  the  Cam- 
bridge Transactions  has  led  both  Mr.  Earnshaw  and  Mr. 
O'Brien  astray.  I  ought  to  take  the  blame  of  this  on  myself, 
and  do  so ;  your  readers  will  find  my  acknowledgement  of  it 
at  p.  347  of  the  last  Number  of  your  Journal.  The  three 
quantities  which  Mr.  Earnshaw  copies  in  p.  341  are  not  equal. 
I  supposed  the  axis  of  y  to  be  that  along  which  transmission 
takes  place,  and  ought  to  have  made  the  first  and  last  ex- 
pression equal  to  «2,  and  the  middle  one  to  wx2;  and  so  in  my 
own  copy  it  is,  but  I  presume  the  correction  was  made  with 
a  pen.  The  equality  of  these  two  expressions  has  been  em- 
ployed by  Mr.  O'Brien  to  prove  that  I  do  not  suppose  the 
axis  of  y  to  coincide  with  the  direction  of  transmission  ;  and 
if,  in  applying  the  equations  I  had  used  these  quantities  as 
equal,  the  argument  would  have  been  a  strong  one.     But  on 


The  Rev.  Professor  Challis  in  Reply  to  Mr.  Stokes.    423 

turning  to  Camb.  Trans.,  vol.  vi.  p.  180,  it  will  be  seen  that 
I  have  proved  them  to  be  unequal.  I  am  truly  sorry  that  this 
misprint,  or  mis-transcription,  or  whatever  it  may  be,  has 
caused  so  much  trouble.  It  was  very  natural  that  it  should 
mislead  Mr.  Earnshaw,  and  produce  the  argument  at  p.  342 
of  Nov.' Phil.  Mag.  ;  but  I  should  have  hardly  imagined  it 
possible  to  have  deceived  Mr.  O'Brien,  who  appears  to  have 
perceived  (see  his  P.S.  p.  34:3)  that  I  supposed  the  axis  ofy 
to  be  in  the  direction  of  transmission. 

For  having  given  these  gentlemen  the  trouble  of  arguing 
the  incorrectness  of  equations  which  are  undoubtedly  erro- 
neous (if  u  is  not  nx  in  the  last  line  of  p.  162),  I  hope  they 
will  accept  my  apology. 

I  am,  dear  Sir,  with  great  respect, 
Your  obliged  Servant, 

Edinburgh,  Nov.  2, 1842.  P.  KELLAND. 

LXXV.  On  the  Analytical  Condition  of  Rectilinear  Fluid  Mo- 
tion, in  Reply  to  Mr.  Stokes's  Remarks.  By  the  Rev.  J. 
Challis,  M.A.,  Plumian  Professor  of  Astronomy  in  the  Uni- 
versity of  Cambridge*. 

TV/I  R.  STOKES  has  brought  forward  four  arguments  against 
-L"J'  a  new  theorem  in  hydrodynamics  which  I  have  advanced, 
viz.  that  fluid  motion  is  rectilinear  whenever  udx  +  vdy+wdz 
is  an  exact  differential.  The  observations  I  am  about  to  make 
in  reply  will  follow  the  order  of  the  arguments. 

1.  In  the  first  argument  (p.  297)  it  is  contended  that  my  de- 
monstration in  the  August  Number  of  this  Journal  is  deficient 
in  generality,  because  it  takes  no  account  of  the  curvature  of 
the  lines  of  motion.  I  admit  the  validity  of  this  objection.  The 
geometrical  reasoning  I  have  there  given  proves  only  that 
u  dx  +  vdy  +  iadz  is  an  exact  differential  when  the  motion 
is  rectilinear,  if  the  surfaces  of  displacement  are  surfaces  of 
equal  velocity.  I  have  not  proved,  as  Mr.  Stokes  asserts,  that 
for  the  case  of  rectilinear  motion  the  surfaces  of  displacement 
are  surfaces  of  equal  velocity.  This  is  not  necessarily  the 
case  unless  udx  +  vdy  +  wd she  an  exact  differential. 

The  following  demonstration  derived  from  the  equation 
udx  +  vdy  +  isodz  =  V dr,  is  more  to  the  purpose.  In 
this  equation  V  is  the  velocity  at  a  point  whose  coordinates 
are  x,  y,  z  at  a  given  time ;  u,  v,  to  are  the  components  of  V 
in  the  directions  of  the  axes  of  coordinates ;  and  d  r  is  the 
increment  of  space  in  the  direction  of  the  motion  through  the 
point  xyss.  The  proof  of  the  equation  is  sufficiently  well 
known. 

*  Communicated  by  the  Author. 


424-     The  Rev.  Prof.  Challis  on  the  Analytical  Condition  of 

"Let  udx  +  vdy  +  wdss  be  an  exact  differential.  Then, 
and  not  otherwise,  it  is  possible  to  integrate  this  quantity,  and 
consequently  its  equivalent  V  dr, 
from  any  one  point  of  the  fluid  to 
any  other.  P  and  Q  (in  the  figure) 
being  any  two  points  in  the  fluid, 
let  P  R  be  the  line  of  direction  of 
motion  through  P  at  a  given  time, 
and  let  Q  R  represent  the  sur- 
face of  displacement  through  Qat 
the  same  time.  The  integral  of 
u  d  x  +  v  dy  +  iv  d  z,  and  therefore  that  of  V  d  r,  may  be 
taken  indifferently  along  the  line  P  Q,  or  along  P  R  and  R  Q. 
But  the  integral  of  V  d  r  along  R  Q  is  nothing,  because  by 
hypothesis  this  line  is  on  a  surface  of  displacement.  There- 
fore the  integral  of  V  d  r  from  P  to  R  is  identical  with  the  in- 
tegral from  P  to  Q.     Hence  if  S  be  the  integral,  the  differ- 

ential  coefficient  -7—,  which  is  the  velocity  at  R,  is  also  the 

dr  J  ' 

velocity  at  Q.  This  reasoning  applies  wherever  the  point  Q 
is  situated  on  the  surface  of  displacement.  Hence  this  surface 
is  a  surface  of  equal  velocity.  Draw  another  surface  of  dis- 
placement indefinitely  near  the  former.  Then  if  S-f  8  S  be 
the  integral  of  V  d  r  from  P  to  r,  the  same  will  be  the  inte- 
gral from  P  to  q ;  consequently,  Q  5  being  drawn  through 
Q  in  the  direction  of  the  motion  at  that  point,  we  have  ulti- 
mately, 8  S  =  -r~  x  the  line  Q  s,  and  8  S  =  -7—  x  the  line  Rr. 
*  dr  dr 

Hence  Q  s,  which  is  ultimately  the  interval  between  the  sur- 
faces of  displacement  at  Q,  is  equal  to  Rr  the  interval  be- 
tween them  at  R.  It  follows  that  the  surfaces  are  at  all  points 
equidistant,  and  therefore  parallel.  A  normal  to  one  is  there- 
fore accurately  a  normal  to  the  other,  and  the  lines  of  direc- 
tion of  motion  are  consequently  rectilinear. 

The  above  reasoning  proves  that  whenever  udx  +  vdy 
-f  w  d  z  is  an  exact  differential  the  motion  is  rectilinear.  This 
is  the  important  part  of  the  theorem  I  have  announced,  and 
it  is  all  that  there  is  any  occasion  to  contend  for.  In  my  pre- 
ceding communication  I  said  incorrectly  that  the  exactness  of 
that  differential  is  a  necessary  condition  of  rectilinear  motion. 
Nothing  that  I  have  advanced  disproves  the  possibility  of  there 
being  rectilinear  motion  when  udx  +  vdy  +  wdz  is  not  an 
exact  differential. 

2.  If  u, vf  w  be  functions  of  the  time,   and  udx  4-  vdy 


Rectilinear  Fluid  Motion^  in  Reply  to  Mr.  Stokes.      425 

+  wdz  =  0,  then  by  a  common  step  in  analytical  reasoning, 

du  .         dv  ,  dw  j  _  .j    ,    ,        ,       ,      , 

d~t     ^+  It     y  +  dT  }  provided  dx9  dy,  dz  do  not 

vary  with  the  time.  Hence  as  it  is  proved  above  that  dx,  dy, 
dz  do  not  vary  with  the  time  in  the  equation  udx  +  vdy 
-f  tods  =0,  when  the  left-hand  side  is  an  exact  differential 

(d  <p),  it  appears  that  d  $  =  0,  and  d .  —r-  =  0,  are  differ- 

£ 

ential  equations  of  the  same  curve  surface.  The  following  is 
an  instance.  Let  the  velocity  V  be  directed  to  or  from  a 
fixed  centre  whose  coordinates  are  a,  /3,  y,  and  be  the  same 
at  the  same  distance  (r)  from  the  centre  at  a  given  time. 
Then  because 

tidx+vdy+wdz,  orV.f dx  +  ~ — ?  dy-\ ^dzJ^O, 

it  follows  that 

du    .        dv    7     ,    dw  j 

-dTdx+-ndy+-dtd*> or 


dx  + 
dt     \    r  r 


^+  -f1  dz)  =°» 


and  these  are  differential  equations  of  the  same  curve  surface. 

3.  In  answer  to  the  third  argument  it  is  sufficient  to  say, 
that  any  proposition  proved  respecting  Jluid  motion,  that  is, 
motion  by  which  the  parts  of  the  fluid  alter  their  relative  po- 
sitions, cannot  be  affected  by  motion  which  is  common  to  all 
the  parts.  There  is  no  dependence  of  the  one  kind  of  motion 
on  the  other.  The  equation  of  continuity  and  the  equation 
derived  from  D'Alembert's  principle  are  identically  satisfied 
by  the  latter  kind  of  motion,  which  must  be  considered  to  be 
eliminated  before  any  use  is  made  of  those  equations  for  de- 
termining fluid  motion. 

4.  The  solution  here  given  of  a  bydrodynamical  problem 
is  inadmissible  on  this  ground.  If  a  direct  solution  of  the 
problem  had  been  attempted,  it  would  have  been  found  ne- 
cessary to  inquire  whether  ud  w  +  v  dy  +  wd  z  were  an  ex- 
act differential  for  that  instance ;  and  no  mode  of  solution 
could  evade  the  consideration  of  this  question,  unless  the  fluid 
were  supposed  to  be  confined  between  two  cylindrical  surfaces 
indefinitely  near  each  other,  and  having  hyperbolic  bases. 
As  in  Mr.  Stokes's  solution  that  question  is.  not  considered, 
I  conclude  that  it  only  applies  to  the  limited  case. 

There  is  another  point  connected  with  this  subject,  and  of 
no  little  consequence  in  the  mathematical  theory  of  fluid  mo- 


426  Dr.  Waller's  Experiments  on  the 

tion,  which  I  am  desirous  of  adverting  to.  In  my  former 
communication  I  inferred  from  the  writings  of  Poisson  that 
he  did  not  accede  to  a  proposition  which  occurs  in  the  Me- 
canique  Analytique,  viz.  that  udx+  vdy  +  wdz  is  an  exact 
differential  whenever  the  motion  is  small.  But  I  am  not 
aware  that  any  general  reason  has  been  given  for  concluding 
that  this  proposition  is  untrue.  By  putting  g  for  the  density 
of  the  fluid,  and  P  for  h .  Nap.  log.  g,  and  neglecting  powers 
of  u9  v,  and  w  above  the  first,  we  have  the  known  equations, 

dP        du  dj?       dv_  dV^      dw  _ 

~dlf+  dt  ~  '  dy  +  dt  '  dz  +  dt  ~0; 
the  impressed  forces  for  shortness'  sake  being  omitted.  Hence 
approximately, 

du        dv         du        duo         dv         dta 
dy        dx9       d z   "  dx  f       dz  dy   ' 

and  it  might  be  argued  from  these  equations  that  udx+vdy 
+  1KJ  d  z  is  an  exact  differential  for  small  motions,  whether  they 
are  rectilinear  or  not.  But  the  answer  is,  that  the  condition 
of  integrability  requires  that  those  equations  should  be  identi- 
cally true,  which  they  cannot  be  said  to  be,  because  powers 
of  u,  v,id  above  the  first  have  been  omitted. 

The  same  answer  applies  in  another  instance.  If  fluid  issues 
at  a  constant  rate  from  an  orifice  in  a  vessel  of  indefinitely 
large  dimensions,  it  may  be  shown  that  the  conditions  of  in- 
tegrability of  udx  +  v  dy  +  isodz  are  satisfied  if  the  motion 
at  parts  infinitely  distant  from  the  orifice  be  neglected.  Those 
equations  are,  therefore,  numerically  satisfied ;  but  as  a  state 
of  motion  differs  from  a  state  of  rest  however  large  the  vessel 
may  be,  it  follows  that  they  are  not  identically  satisfied,  and 
it  cannot  therefore  be  concluded  that  u  d  x  +  v  dy  + 10  d  is  is 
in  this  instance  an  exact  differential. 

Cambridge  Observatory,  Oct.  22, 1842. 


LXXVI.  Experiments  on  the  coloured  Films  formed  by  Iodine, 
Bromine,  and  Chlorine  upon  various  Metals.  By  Augustus 
Waller,  M.D.* 

IN  a  paper  presented  by  me  to  the  Academy  of  Sciences  of 
Paris,  an  extract  from  which  may  be  seen  in  the  Comptes 
Rendus  for  October  5,  1840,  I  first  demonstrated  the  error 
committed  in  ascribing  to  the  iodide  of  silver  alone  the  power 
of  fixing  the  vapours  of  mercury,  after  it  had  been  exposed 

*  Communicated  by  the  Author. 


coloured  Films  formed  by  Iodine,  fyc.  upon  Metals.      427 

to  the  action  of  light.  Instead  of  this  property  being  ex- 
clusively confined  to  a  film  of  iodide  of  silver,  as  obtained 
in  the  process  of  M.  Daguerre,  I  found  that  it  existed  in 
many  other  substances  when  presented  to  the  action  of  light 
in  the  state  of  thin  films,  viz.  by  the  bromide  and  chloride  of 
silver ;  by  the  oxide,  bromide,  iodide  and  chloride  of  copper 
and  some  others ;  all  these  however  possessing  less  sensibility 
than  the  iodide  of  silver  of  Daguerre,  and  therefore  less  avail- 
able for  the  reproduction  of  the  images  of  the  camera  than 
the  compound  originally  discovered  by  that  gentleman.  The 
iodide  of  Daguerre  was  found  already  too  little  sensitive  to 
the  influence  of  light  in  this  climate,  especially  when  applied 
to  the  reproduction  of  the  image  of  animate  objects,  so  that 
those  films  discovered  by  me  seemed  still  less  suitable-  to  be 
employed  for  that  purpose ;  this  objection  has,  however,  been 
completely  removed  by  recent  improvements,  more  particularly 
those  of  M.  Claudet,  who  effected  this  principally  by  com- 
bining the  original  discovery  of  Daguerre  with  those  men- 
tioned above  as  having  been  subsequently  made  by  myself. 
Pursuing  the  first  stage  of  Daguerre's  process,  he  obtained 
the  film  of  iodide  of  silver,  and,  added  to  this  another  film  of 
bromide,  either  in  a  simple  state, — as  practised  in  my  experi- 
ments published  more  than  six  months  before, — or  after  two  of 
these  substances  had  been  combined  together,  as  the  chloride 
of  iodine  and  the  bromide  of  iodine,  which  he  was  the  first 
to  employ. 

These  coloured  films,  however,  merit  attention  independ- 
ently of  the  purposes  to  which  they  may  be  applied  in  pho- 
tography :  the  beauty  of  some  of  the  phaenomena  themselves 
is  peculiarly  attractive ;  the  numerous  changes  of  colour  they 
undergo,  either  by  a  variation  in  the  thickness  of  the  film,  or 
by  the  action  of  light,  assign  them  a  place  among  the  most 
curious  facts  of  science,  and  the  extreme  facility  with  which 
they  are  obtained  adds  to  the  interest  they  excite. 

Impressed  with  these  ideas,  I  was  induced  to  pursue  a  train 
of  investigation  on  this  subject;  among  the  results  of  which,, 
one  of  the  most  interesting  was  a  new  method  of  making  co- 
loured rings,  like  those  generally  known  under  the  name  of 
"  Newton's  coloured  rings,"  on  many  of  the  metals,  by  the 
same  chemical  process  as  that  employed  for  forming  the  films 
of  uniform  thickness  in  photography.  In  order  to  procure  these 
coloured  rings,  and  at  the  same  time  to  show  the  identity  of 
the  origin  of  the  colours  with  those  of  the  ordinary  transpa- 
rent films,  that  is,  as  residing  simply  in  the  thickness  of  the 
lamina  and  not  dependent  on  the  ordinary  cause  of  colour, 
we  have  but  to  place  a  piece  of  iodine  on  a  well-polished  sur- 


428  Dr.  Waller's  Experiments  on  the 

face  of  silver  or  copper,  and  in  a  short  time  we  find  around 
the  iodine  a  series  of  coloured  zones  of  the  various  tints  of 
the  spectrum,  and  approaching  in  a  greater  or  less  degree  to 
the  form  of  a  circle,  according  as  they  have  been  more  or  less 
disturbed  in  their  formation  by  currents  of  the  surrounding 
air.  In  order  that  they  may  be  perfectly  regular,  as  large  as 
possible,  and  with  tints  undisturbed  by  the  action  of  light,  it 
is  necessary  to  place  a  piece  of  iodine  in  the  centre  of  a  well- 
polished  plate,  as  before  described ;  this  is  then  to  be  shaded 
by  an  opake  screen  superimposed  a  few  lines  from  the  surface 
to  cause  the  vapours  which  would  otherwise  ascend  and  par- 
tially escape,  to  expand  over  its  silver  surface.  Coloured 
rings  may  be  formed  in  the  same  manner  by  bromine  and 
chlorine  and  the  various  combinations  of  these  bodies  with 
each  other,  except  that  for  those  that  are  gaseous  or  liquid  it 
is  requisite  to  pay  a  little  attention  to  the  manner  of  disen- 
gaging them  on  the  surface  of  the  metal,  either  by  passing 
them  through  a  glass  tube,  or  by  some  other  contrivance  easy 
to  execute.  These  rings  correspond  to  those  formed  by  re- 
flected light  in  Newton's  experiments,  with  this  difference, 
however,  that  in  the  coloured  films  of  the  soap  bubble,  and 
in  those  formed  by  the  glass  lenses,  the  thinnest  film  is  in  the 
centre ;  whilst  in  these  rings,  obtained  by  chemical  action,  it 
exists  at  the  circumference,  as  is  the  case  with  the  coloured 
rings  of  Nobili.  In  watching  the  formation  of  these  pheno- 
mena, at  first  are  seen  two  or  three  very  small  circles,  {which 
appear  almost  as  soon  as  the  iodine  and  the  metal  are  placed  in 
contact  with  each  other ;  as  the  experiment  continues,  the  cir- 
cumferences of  these  circles  become  gradually  greater ;  whilst 
the  external  colours  extend  themselves  over  a  greater  space, 
those  of  the  centre  grow  fainter ;  red  and  green  now  only  re- 
main visible,  and  these  at  last,  when  the  film  has  attained  a 
certain  thickness,  in  their  turn  also  give  place  to  a  dull  coating 
of  brown.  The  formation  of  these  rings  evidently  depends 
on  the  vaporization  of  the  iodine  from  the  solid  nucleus.  The 
variety  in  colour  and  extent  of  these  zones  is  caused  by  the 
difference  between  the  strength  of  the  vapour  at  the  centre 
and  the  circumference  of  the  iodic  atmosphere  whilst  expand- 
ing over  so  large  a  surface.  In  the  metal  thus  combining  with 
the  vapour,  we  have  to  consider, — 1,  the  force  of  the  vapour 
at  different  distances  from  the  centre ;  2,  the  obstacle  which 
a  film  of  iodine,  once  formed,  opposes  to  any  further  action 
between  the  iodine  and  the  metal. 

This  experiment  may  be  varied  in  different  ways:  two 
pieces  of  iodine  of  about  the  same  size,  placed  at  a  small  di- 
stance from  each  other  on  a  silver  plate,  form  separate  co- 


coloured  Films  formed  by  Iodi?ie,  fyc.  upon  Metals.      429 

loured  circles,  until  these  come  in  contact  at  their  circum- 
ferences, when  the  two  systems  will  slowly  coalesce  and  pro- 
duce one  common  outline  of  the  form  of  an  ellipsis. 

As  the  colours  formed  on  various  metals  by  the  above-men- 
tioned agents  are  very  similar  to  one  another,  it  may  be  suffi- 
cient to  examine  in  particular  those  produced  on  silver  by 
iodine. 

The  external  film  of  the  iodide  of  silver  rings,  which  cor- 
responds to  the  central  black  spot  in  those  of  Newton,  is  com- 
pletely invisible,  it  being  impossible  to  perceive  any  difference 
between  the  parts  so  covered,  and  those  where  the  metal  is 
intact ;  but  by  exposing  half  the  plate  to  the  influence  of  light, 
whilst  the  other  part  remains  covered,  the  silver  is  then  found 
darkened  far  beyond  the  limits  of  the  external  gold-coloured 
zone,  where  previously  the  surface  was  perfectly  clear.  The 
dark  film  thus  rendered  apparent  is  now  liable  to  be  rubbed 
off  by  the  slightest  friction,  whereas  before  it  was  very  adhe- 
rent to  the  subjacent  surface.  The  first  zone  is  of  a  pale  gold 
colour,  which  assumes  a  deeper  tint  as  the  thickness  of  the 
film  increases :  the  second  zone  is  blue,  the  third  white  ? 
after  these  appear  the  different  colours  of  the  spectrum  in  re- 
gular succession,  as  in  the  films  studied  by  Newton  and  others, 
viz.  yellow,  orange,  red,  blue,  green,  yellow,  &c.  The  pre- 
sence of  the  golden-coloured  zone  in  the  place  mentioned  is 
worthy  of  remark,  as  in  the  tables  of  Newton  of  the  colours 
presented  by  films  of  various  thicknesses,  the  blue  is  stated  as 
immediately  following  the  black.  The  same  gold  film  is  the 
first  which  appears  on  most  metals  when  their  surface  is  at- 
tacked in  this  manner.  Chlorine  and  bromine  on  silver ; 
oxygen  on  steel ;  chlorine  and  bromine  on  titanium,  bismuth, 
&c,  commence  their  colours  in  the  same  way.  Copper,  how- 
ever, is  in  one  respect  an  exception,  this  metal  first  becoming 
of  a  dark  red,  which  increases  to  a  ruddy  brown  and  then 
changes  into  blue ;  this  deviation  is  fully  accounted  for  by  the 
colour  of  the  copper  itself;  with  this  single  particularity,  this 
metal  undergoes  the  same  alterations  as  the  others. 

The  action  of  light  on  the  different  colours  of  the  iodide  of 
silver  is  very  interesting :  the  most  correct  way  of  studying 
this  is  to  protect  one  half  of  a  system  of  coloured  rings  by  an 
opake  screen,  while  the  other  half  is  exposed  for  a  short  time 
to  the  influence  of  the  solar  rays.  The  golden  zone  undergoes 
the  greatest  change  ;  at  first  it  grows  darker,  then  red,  and 
at  length  is  converted  into  a  beautiful  green.  The  blue  film, 
which  comes  next  in  thickness,  suffers  considerable  alteration 
in  its  tint,  assuming  a  much  deeper  and  more  brilliant  shade  ; 
the  rest  of  the  colours  appear  to  be  similarly  affected  by  the 


430  Dr.  Waller's  Experiments  on  the 

action  of  light,  though  to  a  very  slight  degree,  acquiring  a 
trifling  accession  in  their  brilliancy.  It  has  already  been  re- 
marked that  light  destroys  the  adherence  of  the  external  in- 
visible film:  the  same  thing  obtains  with  the  second  or  gold- 
coloured  film,  which  turns  green,  but  only  to  a  certain  depth 
of  the  film,  as  may  be  proved  by  slightly  rubbing  the  part 
thus  altered ;  the  green  colour  is  then  seen  to  disappear,  and 
beneath  the  pulverulent  portion  thus  removed  is  found  the 
gold  colour,  having  almost  the  same  appearance  as  before 
the  plate  had  been  exposed.  As  this  experiment  may  be  re- 
peated several  times  with  the  same  results,  it  shows  to  how 
inconceivably  small  a  depth  the  light  has  acted  to  produce 
this  effect.  To  ascertain  what  would  take  place  on  augment- 
ing the  thickness  of  the  portion  turned  green,  and  the  ad- 
herence of  which  was  destroyed,  a  piece  of  iodine  was  placed 
on  the  plate  so  that  its  vapour,  by  expanding,  might  arrive 
upon  the  green,  at  the  same  time  the  whole  being  kept  from 
the  light;  the  result  was  that  the  additional  film  combined  with 
the  one  already  existing,  producing  a  blue,  being  the  colour 
which  would  have  resulted  by  the  combination  of  the  unal- 
tered yellow  films.  I  have  found  no  chemical  substance  pos- 
sessing the  power  of  arresting,  or  in  anyway  influencing  these 
changes  of  colour ;  strong  acids,  provided  they  do  not  attack 
the  silver, — for  then,  of  course,  the  experiment  would  be  de- 
stroyed,— and  alkalies  in  concentrated  solution,  allow  the  ac- 
tion of  light  to  go  on  as  usual.  The  hyposulphite  of  soda,  and 
ammonia  in  solution  have  no  longer  the  power  of  dissolving 
the  green  film  as  they  had  before  the  action  of  light. 

When  the  plate  is  left  still  longer  exposed,  after  the  changes 
above  stated  have  taken  place,  the  colours  become  more  faint, 
and  within  the  zone  of  green  a  white  cloudy  film  is  caused  by 
the  light,  which,  as  it  increases,  veils  the  spectral  colours  be- 
neath. 

The  knowledge  we  at  present  possess  in  chemistry  of  the 
affinities  with  which  different  bodies  are  endowed  for  com- 
bining with  each  other  is  but  very  imperfect,  and  the  causes 
which  complicate  most  chemical  phenomena  are  so  numerous, 
that  it  is  scarcely  possible  to  compare  any  two  chemical  ac- 
tions to  each  other.  Most  of  the  facts  upon  which  chemical 
science  is  founded,  are  acquired  either  by  bringing  the  two 
bodies  destined  to  act  on  each  other  into  contact  by  dissolving 
them  in  a  liquid,  or  by  subjecting  them  to  a  temperature  more 
or  less  elevated. 

In  the  first  of  these  methods,  we  are  so  far  from  being  able 
to  calculate  the  force  of  the  chemical  powers  called  into  play, 
that  Berthollet  was  induced  to  deny  the  existence  of  chemical 


coloured  Films  formed  by  Iodine,  Sfc.  upon  Metals,      431 

power  in  the  various  phaenomena  of  solution  and  precipitation 
of  saline  substances,  and  according  to  him  what  is  called  inso- 
lubility in  a  body  is  merely  the  result  of  its  strength  of  cohe- 
sion, an  entirely  physical  property. 

When  the  intervention  of  caloric  is  required,  the  effects  are 
still  more  complicated,  as  they  vary  according  to  the  intensity 
of  the  heat  employed,  and  the  time  its  action  is  exerted ;  be- 
sides, the  chemical  action  when  it  does  take  place  is  frequently 
so  instantaneous  that  it  is  impossible  in  our  present  state  of 
science  to  imagine  any  means  by  which  it  might  be  measured. 
In  the  combination  of  the  three  bodies,  iodine,  bromine  and 
chlorine,  with  the  metals,  however,  most  of  these  objections  cease 
to  exist,  or  may  be  easily  avoided.  As  their  vapours  com- 
bine with  the  metallic  surfaces  at  the  ordinary  temperature, 
they  are  all  of  them  in  the  same  circumstances  in  that  respect ; 
and  if  the  temperature  should  be  required  more  elevated,  the 
gasiform  state  of  these  substances,  iodine  not  excepted,  en- 
ables us  to  submit  the  metals  to  be  experimented  upon  all 
at  the  same  time  to  the  same  influence.  If,  therefore,  it  were 
possible  to  reduce  the  metallic  substances  into  fine  powders 
the  particles  of  which  were  of  the  same  dimensions,  by  acting 
upon  them  with  either  of  these  vapours,  an  idea  might  be 
formed  of  the  affinities  which  produce  their  binary  com- 
pounds by  the  increased  weight  acquired  by  the  powders  in 
this  process  ;  but  the  difference  which  exists  in  the  physical 
properties  of  the  various  metals  would  preclude  the  possibility 
of  any  near  approach  to  accuracy  in  this  mode  of  proceeding ; 
but  by  acting  on  the  polished  metallic  surfaces,  as  in  the  pre- 
ceding experiments,  all  the  advantages  offered  by  the  process 
with  the  powders  are  included,  whilst  several  of  the  difficulties 
are  removed.  As  the  film  of  the  compound  augments,  it  un- 
dergoes the  various  changes  of  colour  which  take  place  in  all 
transparent  films,  thus  affording  a  means  of  ascertaining  the 
absolute  thickness  obtained  in  different  circumstances,  when 
it  would  be  difficult  to  detect  the  slightest  difference  in  weight 
by  means  of  the  most  delicate  balance.  The  depth  of  this 
coating  may  be  ascertained  when  either  the  index  of  refrac- 
tion of  the  compound  itself  is  known,  or  if  the  angle  of  po- 
larized light  is  given  by  means  of  the  law  discovered  by  Sir 
David  Brewster,  between  the  tangent  of  the  angle  of  polari- 
zation, and  the  index  of  refraction.  The  most  convenient 
way  which  occurred  to  me  of  performing  these  experiments, 
was  the  employment  of  a  bell-glass  within  which  some  iodine 
is  fixed  at  the  top ;  this  apparatus  being  placed  over  the  metal 
to  be  acted  on,  the  experiment  may  be  watched  in  all  its  pro- 
gress, and  the  action  can  be  retarded  or  accelerated  at  plea- 


432 


Dr.  Waller's  Experiments  on  the 


sure  by  varying  the  interval  of  the  iodine  from  the  metal,  or 
by  interposing  at  some  distance  from  its  surface  a  disc  of  pa- 
per so  as  to  cause  the  vapours  of  iodine  to  pass  through  it. 
Bromine  may  be  made  use  of  likewise  by  pouring  a  few  drops 
of  it  over  some  carded  cotton,  and  using  it  in  a  similar  man- 
ner with  the  iodine.  In  respect  to  chlorine,  it  is  most  con- 
venient to  disengage  it  slowly  by  dropping  a  little  sulphuric 
acid  upon  some  chlorinated  lime. 

In  illustration  of  the  objects  of  this  mode  of  experimenting, 
I  will  adduce  some  of  the  results  it  has  given  me  with  various 
metals.  Some  of  the  experiments  below  were  performed  be- 
fore I  had  the  idea  of  watching  the  progress  of  the  combina- 
tion through  a  transparent  medium ;  they  are  therefore  less 
exact  than  they  might  otherwise  have  been  :  but  I  have  pre- 
ferred stating  them  as  I  had  inserted  them  in  my  note-book 
befoie  I  had  conceived  any  idea  as  to  their  probable  utility  in 
the  elucidation  of  chemical  affinity,  and  when  I  intended  them 
for  other  purposes,  which  I  shall  hereafter  explain. 


Iodine  with  Silver  and  Copper. 

1st  change, 

,  Silver 

.  .  .  pale  gold. 

•  •• 

Copper 

.  .  .  assumes  a  darker  red. 

•  •• 

Silver 

.  .  .  blue. 

2nd  do. 

Copper 

.  .  .  blue. 

••• 

Silver 

.  .  .  white. 

3rd    do. 

Copper 

.  .  .  white. 

•  •• 

Silver 

.  .  .  yellow.                                   [silver. 

4th  do. 

Copper 

.  .  .  yellow  more  extended  than  on  the 

•  •• 

Silver 

.   .  .  orange. 

5th    do. 

Copper 

.   .  .  red. 

••• 

Silver 

.  .  .  blue,  bluish-red.                   [parts. 

... 

Copper 

.  .  .  red,  with  a  tinge  of  green  on  some 

... 

Silver 

.  .  .  greenish  blue. 

... 

Copper 

.  .  .  red,  tinged  with  green. 

... 

Silver 

.  .  .  green. 

••• 

Copper 

.  .  .  orange. 

••• 

Silver 

.  .  .  yellowish  green. 

••• 

Copper 

.  .  .  orange  tending  to  red. 

... 

Silver 

.  .  •.  yellowish  green. 

... 

Copper 

.  .  .  orange-red. 

••• 

Silver 

.  .  .  red. 

••• 

Copper 

.  .  .  dull  green. 

•«• 

Silver 

.  .  .  red. 

••• 

Copper 

.  .  .  green. 

•«• 

Silver 

.  .  .  deep  green. 

••• 

Copper 

.  .  .  dull  red. 

coloured  Films  formed  by  Iodine,  fyc.  upon  Metals.        433 
Bromine  with  Silver  and  Copper. 


5th  change.  Copper 
Silver 
Copper 
Silver 
Copper 
Silver 
Copper 
Silver 
Copper 
Silver 


sensibly  darkened. 

unchanged. 

deep  red. 

unchanged. 

red,  blue. 

pale  gold. 

white,  orange  of  the  2nd  order. 

yellow.  [order. 

green  of  the   1st  order,   red  3rd 

blue. 

Chlorine  with  Silver  and  Copper. 
The  affinity  of  chlorine  with  silver  is  much  inferior  to  that 
which  it  possesses  for  copper. 

Iodine  with  Titanium. 
Iodine  at  the  common  temperature  has  no  action  upon  this 
metal. 

Bromine  with  Titanium. 

Bromine,  when  the  surface  of  this  substance  is  perfectly 
dry,  has  no  more  action  upon  it  than  iodine;  but  if  it  have  a 
slight  coating  of  moisture,  as  is  formed  by  merely  condensing 
on  it  the  vapour  of  the  breath,  the  coloured  films  are  formed 
without  difficulty  by  the  vapours  of  bromine.  Their  appear- 
ance is  the  same  as  those  of  the  iodide  of  silver,  viz.  gold, 
deep  gold,  blue,  white,  yellow,  orange,  red,  &c. 

Chlorine  with  Titanium  and  Copper. 
Titanium  has  a  stronger  affinity  than  it  has  for  either  of 
the  preceding  vapours.     The  combination  takes  place  when 
the  metallic  surface  is  either  dry  or  moist. 
Copper      .  .  .  much  reddened. 
Titanium  .  .  .  not  affected. 

f  passed  through  several  of  the  spectral  or- 
Copper     •  •  •"{      ders  °f  red  and  green  until  it  arrived  at 

[_     almost  its  last  changes  of  colours. 
Titanium  under  the  same  action  received  a  dull  film,  which 
viewed  obliquely  showed  red,  green,  yellow. 

Silver,  exposed  to  the  same  influence  as  the  two  former, 
had  yellow  in  the  centre  and  blue  more  externally. 

Iodine  with  Bismuth  and  Silver. 

Silver       .  .  .  pale  gold. 

Bismuth  .  .  .  some  parts  yellow,  others  not  attacked. 
Silver       .  .  .  blue,  white,  yellow,  orange. 
Bismuth  .  .  .  blue,  yellow,  orange. 
Phil.  Mag.  S.  3.  Vol.  21.  No.  140.  Dec.  1842.        2  G 


434  Dr.  Waller's  Experiments  on  the 

In  the  action  of  iodine  on  bismuth,  the  influence  of  the 
physical  condition  of  metallic  surface  is  very  manifest.  The 
crystalline  texture  of  this  metal  may  be  perceived,  and  the 
difference  of  its  hardness  admits,  to  a  certain  point,  of  being 
measured  by  the  difference  of  the  colour  of  the  films  that  are 
formed  on  various  points ;  while  most  parts  are  yellow,  there 
exist  others  of  an  angular  outline  which  remain  still  unat- 
tacked ;  the  same  difference  is  remarked  in  the  other  stages 
of  the  combination. 

Iodine  'with  Mercury. 

It  is  impossible  to  estimate  the  affinity  between  mercury 
and  iodine  by  means  of  the  coloured  films,  because,  on  com- 
bining, these  two  substances  merely  cause  a  dirty  white  ap- 
pearance on  the  surface  of  the  latter.     Their  combining  af- 
finity appears  to  be  considerable,  for  when  exposed  together 
with  silver  the  action  produced  with  both  was  red  at  the 
edges,  little  altered  in  colour;  on  the  rest  of  its  surface  a  dull 
white  film,  in  the  midst  of  which   were  seen  several  dark 
spots,  where  the  metal  was  apparently  unaltered. 
Bromine  with  Mercury  and  Copper. 
J~ Mercury  .  ,  .  gold  colour. 
1st.  "^Copper     t  .  .  slightly  darkened. 
,     f  Mercury  .  .  .  blue. 
ld,\  Copper     .  .  .  dark  red. 


,    J  Mercury.  .  .  green  on  some  parts. 
3rd,  ^copper    ,  #  t  white. 


After  this  the  copper  underwent  its  usual  changes  of  colour 
on  prolonging  the  action  of  the  vapour  of  bromine,  but  the 
colour  of  the  mercury  suffered  no  further  change. 

Chlorine  with  Mercury  and  Copper. 

Mercury  ...  a  slight  film. 

Copper     ...  no  alteration  of  colour. 

Mercury  .  .  .  deep  gold  colour. 

Copper     .  .  .  deep  red  on  some  parts,  blue  on  others. 

Mercury  .  .  .  red  tinged  with  blue. 

Copper     .  .  .  blue,  white. 

Mercury  .  .  .  blue. 

Copper  .  .  .  same  as  before. 
With  respect  to  the  bromide  and  chloride  of  mercury,  it  is 
necessary  to  view  them  obliquely  in  order  to  perceive  all  the 
changes  of  colour  they  undergo;  for  if  looked  at  perpendicu- 
larly, there  is  seen  on  both  a  dull  uneven  film  of  white  which 
reflects  none  of  the  above  colours;  consequently,  to  avoid  any 
error,  the  copper  must  be  inspected  under  the  same  angle. 


coloured  Films  formed  by  Iodine,  fyc.  upon  Metals.      435 

Bromine  "with  Bismuth  and  Silver. 
Silver       .  .  .  pale  gold. 
Bismuth  .  .  .  not  apparently  changed. 
Silver       .  .  .  deep  gold,  blue. 
Bismuth  .  .  .  yellow,  blue. 
Silver       ...  blue,  yellow. 
Bismuth  .  .  .  dull  colourless  film. 

Chlorine  "with  Bismuth  and  Silver. 

Bismuth  is  slowly  attacked  by  chlorine  gas,  much  in  the 
same  way  as  with  iodine  and  bromine  in  vapour. 

Bromine  with  Lead. 
At  the  common  temperature  neither  bromine  nor  chlorine 
forms  coloured  films  upon  this  metal,  which  it  is  very  difficult 
besides  to  bring  to  any  high  state  of  polish  on  account  of  its 
softness.  But  when  lead  is  heated,  as  over  the  flame  of  a 
spirit-lamp,  the  vapours  of  bromine  then  form  very  fine  co- 
loured films,  which  are  in  succession  gold,  deep  blue,  &c. 

Iodine  with  Iron. 

These  two  may  be  made  to  form  coloured  films  when  com- 
bined rapidly  together,  but  generally  a  dull  coating  without 
any  spectral  colour  is  obtained,  on  account  of  the  deliques- 
cence of  that  salt. 

Until  we  know  the  index  of  refraction  of  the  different 
films  enumerated,  it  would  be  impossible  to  give  a  correct 
table  of  the  combining  powers  in  the  experiments  that  have 
been  detailed ;  nor  is  the  table  of  the  relative  thickness  of 
transparent  plates  as  it  has  been  transmitted  to  us  by  Newton, 
sufficient  in  the  present  instance,  if  any  great  degree  of  pre- 
cision be  required.  Besides  these  objections,  it  is  necessary 
before  leaving  this  subject  to  pass  in  review  several  others 
inseparable  from  the  mode  of  performing  the  experiments 
themselves.  The  principal  circumstances  complicating  these 
experiments  and  liable  to  vary  in  different  observations,  are, — 

First,  the  hardness  of  the  metal  acted  upon ;  2ndly,  the 
obstacle  opposed  to  the  continuation  of  chemical  action  by  the 
inert  film  formed  upon  the  metal ;  3rdly,  the  force  of  the  va- 
pours that  attack  the  metal.  The  influence  of  the  texture  of 
the  metallic  surface  on  chemical  action  is  most  evident  when 
bismuth  is  the  metal  employed.  Here  the  chemical  action 
may  be  seen  to  commence  on  small  isolated  portions  of  the 
surface,  which  have  already  assumed  a  deep  gold  colour,  be- 
fore other  parts  are  in  the  least  changed,  from  the  natural 
appearance  of  the  metal.  To  determine  how  far  this  might 
influence  the  formation  of  the  iodide  of  silver,  a  silver  coin 

2G2 


Pure  silver 
Silver  coin 
Pure  silver 
Silver  coin 
Pure  silver 
Silver  coin 
Pure  silver 
Silver  coin 
Pure  silver 
Silver  coin 
Pure  silver 


436        Dr.  Waller's  Experiments  on  Coloured  Films. 

was  exposed  to  iodine  with  a  piece  of  pure  silver;  as  the 
former  was  so  much  the  harder  of  the  two,  it  was  naturally 
supposed  that  the  chemical  action  would  be  slower  in  exerting 
itself  on  it  than  on  the  latter.  This,  however,  was  not  the 
case,  as  may  be  seen  by  the  following  statement  of  the  result 
of  the  experiment : — 

Silver  coin  .  .  .  pale  gold  colour, 
pale  gold, 
deep  gold, 
deep  gold, 
light  blue, 
light  blue, 
yellow. 

blue,  white,  yellow  not  visible, 
yellow,  red  at  edges, 
yellow,  no  red  edges, 
red,  blue  at  edges, 
yellow,  no  red  apparent. 
The  intensity  of  the  resistance  offered  by  the  different  films 
of  iodide  of  silver  to  a  continuation  of  the  chemical  combina- 
tion, may  be  determined  by  noting  the  moment  at  which  the 
various  spectral  tints  make  their  appearance. 

Colour  of  the  film  of  iodide  of  silver. 
.  .     beginning  to  darken. 
.  .     pale  gold. 
.  .     deep  gold. 
.  .    orange  blue. 
.  .     blue. 
.  .     light  blue. 

.  .     commencement  of  yellow. 
.  .     orange  red. 
.  .     blue. 
.  .     deep  blue. 
.  .     green. 
.  .     yellowish  green. 
.  .     ruddy  brown. 
.  .    green. 
.  .     green. 
.  .     red. 
.  .     green. 

By  comparing  the  thickness  of  the  colours  with  the  space 
of  time  required  for  their  production,  it  will  be  found,  how- 
ever imperfect  the  table  given  by  Newton  may  be  when  ap- 
plied to  this  subject,  that  towards  the  end  of  the  experiment 
above  given,  the  chemical  combination  is  retarded  by  the  pre- 
sence of  the  inert  film,  and  that  to  obtain  the  same  thickness 


4 

0 

50 

2 

0 

4 

40 

6 

40 

7 

30 

9 

30 

11 

30 

18 

30 

20 

15 

22 

55 

24 

40 

28 

0 

30 

25 

40 

10 

46 

30 

50 

10 

53 

15 

Mr.  Earnshaw's  Reply  to  Prof.  Kelland's  Defence.     437 

of  film  as  at  the  commencement,  about  double  the  time  is  re- 
quired. 

The  third  cause  of  error  may  be  avoided  by  operating  with 
vapours  of  about  the  same  force.  In  those  described,  the 
average  time  employed  in  passing  to  the  maximum  was  ge- 
nerally about  half  an  hour ;  if  that  were  not  taken  into  consi- 
deration, different  results  might  be  obtained. 

In  regard  to  chlorine,  there  exists  another  cause  of  compli- 
cation, the  affinity  which  it  possesses  for  water ;  for  when  dis- 
engaged in  the  ordinary  manner,  chlorine  carries  with  it  a 
certain  quantity  of  water  which  may  very  much  alter  the  re- 
sults of  the  experiment. 
No.  1,  St.  Mary  Abbot's  Terrace,  Kensington. 
[To  be  continued.] 

LXXVII.  Reply  to  Professor  Kelland's  Defence  of  the  New- 
tonian Law  of  Molecular  Action.     By  S.  Earnshaw,  M.A. 


Cambridge  *. 


P 


ROFESSOR  Kelland's  defence  of  the  extension  of  New- 
ton's law  of  force  to  molecular  action  consists  of  a  critique 
upon  my  memoir  "  On  the  Nature  of  Molecular  Forces ;" 
and  of  a  reply  to  my  letter  which  appeared  in  your  Magazine 
for  July  (pres.  vol.  p.  46).  I  shall  therefore  for  the  sake  of 
precision  divide  what  I  have  to  say  in  answer  to  his  remarks 
into  two  corresponding  heads. 

1 .  With  respect  to  the  critique  on  my  memoir,  it  is  evident 
that  it  has  been  written  by  the  Professor  under  the  notion  that 
my  investigations  have  supposed  each  particle  of  the  medium, 
except  the  one  for  which  the  forces  are  calculated,  to  be  in 
their  respective  equilibrium  positions.  I  gather  this  from  the 
repeated  charge  he  brings  against  me  of  drawing  dynamical 
inferences  from  a  statical  investigation.  Will  the  Professor 
point  out  what  step,  in  that  part  of  my  paper  which  is  written 
against  Newton's  law,  requires  that  the  particles  of  the  me- 
dium should  be  in  their  equilibrium  positions  ?  With  the  ex- 
ception of  the  last  article,  where  it  is  expressly  stated  that  the 
particles  are  in  equilibrium,  my  paper  is  an  investigation  of 
the  properties  of  a  vibrating  medium,  i.  e.  a  medium  in  a  state 
of  vibration.  At  any  instant  during  the  motion  of  the  medium 
I  fix  upon  a  particle  and  investigate  the  properties  of  the  forces 
which  urge  it  at  that  moment ;  the  other  particles  meanwhile 
are  supposed  to  be  in  the  positions  which  as  particles  in  a 
state  of  vibration  they  had  at  the  instant  fixed  upon.     [Let 

*  Communicated  by  the  Author. 


438     Mr.  Earnshaw's  Reply  to  Prof.  Kelland's  Defence 

the  Professor  point  out  one  link  of  my  argument  against  New- 
ton's law  which  violates  this  supposition.]     I  find  as  a  result 
that  there  is  always  one  direction  in  which  the  particle  is 
urgedfrom  its  position  of  rest ;  and  therefore,  as  the  motion 
of  the  particle  in  that  direction  could  not  be  vibratory,  New- 
ton's law  cannot  be  the  law  of  molecular  force  in  the  lumini- 
ferous  aether.     This  explanation,  I  trust,  will  enable  the  Pro- 
fessor to  see  that  he  has  written  his  review  of  my  memoir 
under  the  influence  of  a  complete  misconception  of  its  nature, 
to  which  is  due  the  origin  of  his  complaints  that  some  of  my 
reasonings  are  unintelligible  to  him,  and  that  the  whole  line 
of  my  argument  is  inadmissible  (August,  p.  130),  to  which 
charges  it  is  obviously  not  necessary  for  me  to  make  any 
further  reply.  There  is,  however,  one  argument,  which  though 
it  belongs  to  this  head,  I  cannot  allow  to  pass  without  more 
particular  notice,  because  upon  reading  it  I  could  not  but 
consider  it  as  a  strong  indication  of  the  Professor's  having  al- 
lowed other  motives  than  "  a  desire  for  truth  "  (Sept.  p.  207) 
to  influence  him  in  bringing  it  forward.     It  stands  in  the 
Magazine  for  this  month  (p.  270)  in  these  words:  "  I  will  only 
add,  when  it  is  concluded  from  the  hypothesis  of  a  cubical 
arrangement  of  the  particles,  acting  by  forces  which  vary  ac- 
cording to  the  Newtonian  law,  that  the  direction  of  one  side 
of  the  cube  is  stable  and  of  one  unstable,  ought  we  not  to  ask, 
Is  it  the  hypothesis,  or  the  reasoning  based  on  it  which  is  er- 
roneous? Must  it  not  of  necessity  be  the  latter?"     Now  one 
would  think  from  the  manner  in  which  this  argument  is  brought 
forward  that  the  matter  animadverted  upon  by  the  Professor 
forms  a  part  of  my  reasoning.    Your  readers  therefore  will  be 
surprised  to  be  informed  that  it  stands  in  my  memoir  as  a 
purely  casual  observation,  upon  which  not  a  step  nor  even 
a  word  of  my  reasoning    against  Newton's   law   depends. 
Why  then  did  the  Professor  bring  it  forward  and  draw  from 
it  the  sweeping  inference  that  my  reasoning  is  erroneous  ? 
Unfortunately  for  the  Professor,  in  this  instance  he  reaps  no 
advantage  by  stepping  out  of  the  line  of  legitimate  argument, 
as  his  objection  is  founded  on  the  misconception  that  I  have 
supposed  the  particles  to  be  in  equilibrium. 

2.  In  commencing  his  reply  to  my  letter  printed  in  your 
Magazine  of  July,  the  Professor  calls  upon  me  to  state  "  what 
I  conceive  to  be  the  direct  effect  of  matter."  I  conceive  it  to 
be  that  effect  which  arises  from  the  supposition  that  matter 
and  aether  act  upon  each  other  by  attraction  or  repulsion  (en 
passant,  I  do  not  see  why  I  am  called  upon  for  this  definition, 
as  I  have  nowhere  employed  the  direct  action  of  matter).'  By 
the  indirect  action  of  matter  I  mean  that  effect  which  results 


of  the  Newtonian  Lata  of  Molecular  Action.  439 

when  the  density  and  arrangement  of  the  aether  are  changed 
by  the  introduction  of  particles  of  matter  which  exclude  some 
particles  of  aether  from  certain  portions  of  space,  and  thereby 
affect  the  equilibrium  positions  of  the  remaining  particles  of 
aether.  The  Professor  next  endeavours  to  guess  the  reason 
why  I  did  not  draw  from  my  equations  any  inferences  respect- 
ing the  direct  action  of  matter.  The  answer  is  simple ;  a  most 
important  step  required  that  the  vibrating  medium  should 
consist  of  homogeneous  particles.  The  step  I  allude  to  is  that 
where  (S.  3.  vol.  xx.  May,  p.  372)  I  have  "  assumed  the  law  of 
displacement  at  the  time  t  to  be  £r  =  a  sin  (r  h  +  T),"  which 
assumption  is  not  true  when  the  particles  of  matter  vibrate,  be- 
cause then  a  could  not  be  invariable  through  the  medium.  I 
think  no  blame  attaches  to  me  for  causing  this  perplexity  to  the 
Professor,  as  I  have  expressly  added,  "  it  will  be  understood 
that  what  follows  applies  only  to  media  in  which  this  law  of 
disturbance  can  be  transmitted,"  which  I  understand  to  be  a 
formal  renunciation  of  all  connexion  with  the  direct  action  of 
matter.]  The  Professor,  therefore,  in  referringme  to  Mr.  O'  Brien 
(October,  p.  269)  to  be  set  right  in  my  notions,  seems  to  have 
fallen  into  the  mistake  of  supposing  that  what  Mr.  O'Brien 
has  written  on  the  direct  effect  of  matter  (March,  note  at 
p.  208)  can  refute  what  I  have  written  on  the  indirect  effect 
of  matter. 

I  do  not  think  I  fully  understand  on  what  ground  the  Pro- 
fessor affirms  (October,  p.  264)  that  I  have  not  taken  account 
of  "  the  *want  of  action  of  particles  of  aether  in  the  portion  of 
space  occupied  by  the  material  particles"  (October,  p.  264); 
for,  as  I  have  taken  into  account  all  those  particles  of  aether 
which  do  exist,  and  none  else  that  I  am  aware  of,  I  sup- 
pose I  must  have  omitted  those  which  do  not  exist.  Perhaps 
the  Professor  will  point  out  what  step  of  my  investigation 
implies  the  existence  of  the  absent  particles. 

I  am  next  accused  (p.  264)  of  not  saying  a  word  about 
"  the  pressure  of  the  particles  of  matter  on  the  adjacent  parti- 
cles of  aether  tending  to  stop  their  motion."  In  reply  it  seems 
sufficient  to  state,  that  the  particles  of  matter  are  supposed  to 
be  so  few  in  number  in  comparison  with  the  particles  of  aether 
in  a  refracting  medium,  that  though  a  wave  may  in  some  de- 
gree be  broken  up  in  its  passage  through  the  medium  by 
material  impediments,  the  sensible  properties  of  its  general 
front  will  remain  almost,  if  not  entirely  unaffected  ;  wherefore 
in  an  argument  based  on  the  broad  features  of  refraction,  any 
allusion  to  this  consideration  were  a  useless  refinement,  a 
needless  entering  upon  difficulties,  and  an  unnecessary  inter- 


440     Mr.  Earnshaw's  Reply  to  Prof.  Kelland's  Defence 

ruption  of  my  investigations  ;  which  reasons  will,  I  trust,  prove 
satisfactory  to  the  Professor  for  its  having  been  passed  over 
in  silence. 

The  quotation  which  the  Professor  gives  at  the  bottom  of 
p.  265  from  my  letter  (April)  I  can  assure  him  was  not  in- 
tended to  have  any  reference  to  his  writings.  The  Professor 
must  also  have  mistaken  my  views  when  he  states  (p.  266) 
that  I  "appear  to  look  for  a  complete  explanation  of  disper- 
sion to  the  very  quarter  at  which  I  aim  my  objections,"  for 
I  look  to  the  direct  action  of  matter,  against  which  I  have  not 
as  yet  brought  forward  any  objection. 

In  the  middle  of  p.  266  the  Professor  begins  his  reply  to 
my  remarks  on  his  defence  of  his  numerical  calculations.  It 
appears  to  me  that  he  is  hereupon  somewhat  inconsistent 
with  himself.  For  (May,  p.  378)  his  words  are,  "  my  cal- 
culations are  affected  with  an  error,  in  that  /  have  neglected 
to  shorten  A ;  "  but  here  he  writes,  "  the  data  are  not  erro- 
neous." These  two  statements  seem  hardly  reconcilable.  Also, 
if  "  the  calculations  are  affected  with  an  error"  I  do  not  com- 
prehend how  they  can  "  strengthen  theory."  What  he  states 
(p.  267)  about  his  "  formula  admitting  as  many  arbitrary  con- 
stants as  you  please,"  amounts  to  a  confession  that  he  em- 
ployed the  common  principles  of  interpolations,  instead  of 
theory,  which  is  all  I  have  contended  for  in  this  part  of  the 
subject. 

The  latter  part  of  the  Professor's  letter  is  employed  in  con- 
troverting my  remarks  on  his  proof  of  the  transversality  of 
vibrations.  The  values  of  v  u'  v"  which  the  Professor  makes  use 
of  in  establishing  this  principle  are  derived  from  the  equations 
of  motion,  which  in  my  last  letter  I  have  proved  to  be  non- 
existent. That  letter  is  therefore  a  sufficient  answer  to  this 
part  of  the  Professor's  reply.  I  cannot,  however,  dismiss  the 
subject  without  remarking,  that  the  non-existence  of  normal 
vibrations  is  not  proved  when  it  has  been  shown  that  (u) 
the  velocity  of  their  transmission  is  imaginary.  It  must  be 
shown  that  o  is  zero,  or  very  much  greater  or  very  much  less 
than  the  velocity  of  transmission  of  the  transversal  vibrations. 
Por,  if  it  turn  out  that  u  is  imaginary,  the  proper  inference  is, 
as  I  have  before  stated,  that  the  equations  of  motion  have  been 
incorrectly  integrated,  and  the  whole  investigation  needs  to  be 
revised.  As  the  remarks  which  I  have  made  in  my  last  letter 
respecting  the  evanescence  of  the  quantity  n,  and,  with  it,  of 
the  equations  of  motion  extend  to  all  that  the  Professor  has 
written  in  his  Memoirs  on  Light,  and  in  his  Theory  of  Pleat,  as 
far  as  they  are  respectively  dependent  on  Newton's  law  of  mole- 


of  the  Newtonian  Law  of  Molecular  Action.  441 

cular  action,  it  is  needless  to  enter  further  upon  the  inferences 
from  them  which  the  Professor  in  various  parts  of  his  letters 
has  placed  in  opposition  to  my  results. 

It  now  only  remains  to  reply  to  the  accusation  (p.  267)  that 
I  have  fallen  into  an  error  in  turning  the  equations  of  motion 
into  that  form,  from  which  I  drew  all  my  inferences.  I  can 
assure  the  Professor  that  I  did  not  lay  my  investigations  be- 
fore the  public,  without  having  first  carefully  revised  them, 
compared  them  with  what  other  persons  have  written  on  the 
same  subject,  and  satisfied  myself  as  to  the  cause  of  difference 
where  any  existed.  The  Professor  may  therefore  for  the 
future  take  it  for  granted  that  I  have  seen  and  examined  the 
equations  in  M.  Cauchy's  Memoire  sur  la  Dispersion  de  la 
Lumiere,  to  which  he  refers  me  for  correction.  I  fear  it  will 
give  to  my  letter  an  air  of  great  sameness  if  I  again  ac- 
cuse the  Professor  of  misunderstanding  what  he  has  under- 
taken to  criticise.  I  shall  not,  however,  make  the  charge 
without  bringing  forward  the  proof  of  it.  The  Professor  tells 
me  that  the  coefficient  of  a  certain  term  of  my  equations  dif- 
fers in  appearance  from  the  corresponding  coefficient  in  M. 
Cauchy's  equations  ;  and  his  inference  is,  therefore  these  co- 
efficients are  not  equal,  and  therefore  mine  are  erroneous. 
Now  I  ask,  how  does  the  Professor  know  that  these  coeffi- 
cients are  not  equal  ?  I  admit  that  they  appear  to  the  eye  to 
be  different,  but  the  symbol  2)  in  M.  Cauchy's  differs  entirely 
from  the  same  symbol  in  mine.  M.  Cauchy's  coefficients  have 
been  brought  into  the  state  referred  to  by  reductions  sug- 
gested by  theoretical  considerations ;  but  my  coefficients  were 
brought  into  the  state  in  which  I  leave  them  by  reductions 
effected  upon  experimental  grounds.  j  If  M.  Cauchy's  differ  in 
value  from  mine  they  disagree  with  experiment,  and  are  there- 
fore to  be  rejected,  as  will  be  made  manifest  by  the  following 
process,  which  applies  equally  to  M.  Cauchy's  equations  and 
mine  own.  But  I  will  first  state  the  matter  in  another  way. 
In  my  investigations  (March,  p.  372),  A  represents  the  value 
of  2  {m'  <42  F  (R)},  the  summation  represented  by  2  ex- 
tending to  all  particles  in  the  rth  wave  surface,  and  in  all  other 
surfaces  the  particles  of  which  are  in  the  same  state  of  dis- 
placement as  in  the  rth.     Also  A  represents  the  value  of 

2%  f  Arsin2— -J,  2  now  denoting  summation  for  all  the 

values  of  r  in  one  wave's  length.  The  limiting  value  of  r  in 
performing  the  operation  2  is  therefore  the  number  of  par- 
ticles in  a  wave's  length,  which  number  in  any  conceivable 
geometrical  arrangement  of  the  particles  depends  upon  the 


442    Mr.  Earnshaw's  Reply  to  Prof.  Kelland's  Defence 

position  of  the  wave's  front.     Hence  Ar  and  sin2  —  de- 

2 

pend  upon  the  direction  of  transmission ;  but  does  A,  i.  e. 

(t  h  \ 
A'r  sin2  -—  J ,  also  depend  upon  the  direction  of  transmis- 
sion ?  This  question,  and  a  similar  one  for  each  of  the  other 
coefficients,  M.  Cauchy  has  not  answered,  but  I  have  an- 
swered it  for  myself  in  the  negative  on  experimental  grounds, 
as  follows.  My  equations  of  motion  (and  they  are  M.  Cauchy's 
also)  are, 

%*£=  -  A£-F)j~E£ 

dti.m  _Ef-D>j-cr. 

The  question  is,  are  the  coefficients  dependent  on  the  po- 
sition of  the  wave's  front?  Multiply  these  equations  respectively 
by  cos  a,  cos  |3,  cos  y,  and  add  the  results,  at  the  same  time 

7  9  A        .       T*      COS  fi         .       T-«    COS  7  T*  T-v    COS  V 

assuming  ft2  =  A  +  F  —  +  E r-   =   B  +  D  — % 

°  cos  a  cos  a  cos  /3 

-r,  cos  a        ~  ,   -n  cos  a    ,    ,-.  cos  Q      „  ,.,,.. 

+  F ^  =  C  +  E +  D £ ;  from  which  ejrauna- 

cos  p  cos  y  cos  y 

ting  cos  a,  cos  /3,  cos  y,  we  find  the  following  cubic  in  Jc\ 

(£2-A)  (F-B)  (&*-C)-D2  (&2-A)-E2  (F-B) 
-F2(F~C)  =  2DEF. 
Having  from  this  found  three  roots  kt%  k2%  ks%  we  can  then 
find  three  corresponding  sets  of  values  of  cos  «,  cos  /3,  cos  y ; 
and  our  equations  of  motion  by  this  process  of  mere  algebra 
take  the  following  simple  forms, 

d?v  =  --x%  #i  =  -  **%  i*tv  =  - vfc 

where  £'  =  £  cos  «j  +  )j  cos  /32+  $  cos  yj 

V  ss  £  cos  «2  +  >j  cos  &  +  $  cosy2 
£'  =  |  cos  «3  +  )j  cos  /38+  £  cos  y3, 
that  is,  £'  V  £'  are  the  displacements  of  the  particle  m  estimated 
parallel  to  a  new  set  of  rectangular  axes.  The  forms  of  the 
new  equations  of  motion  show  that  these  axes  are  axes  of 
dynamical  symmetry, — those  in  fact  which  are  better  known 
as  the  axes  of  elasticity.  Now  from  experiment  we  know  that 
for  waves  of  a  given  length  k^,  &22,  k32  are  constant  quantities, 
i.  e.  independent  of  the  position  of  the  waves'  front  (by  the 
above  process  I  have  only  changed  the  axes  of  coordinates, 
the  waves'  front  remains  unaltered  in  position).  And  not  to  oc- 
cupy room  unnecessarily,  I  now  refer  the  Professor  to  the  note 
(July,  p.  48)  to  my  letter  for  the  remainder  of  the  proof  that 
"  A,  B,  C,  D,  E,  F  are  independent  of  the  position  of  the 


of  the  Newtonian  Law  of  Molecular  Action.  443 

wave's  front."  By  this  process  it  is  established  beyond  the 
possibility  of  a  doubt,  that  when  the  operation  represented  by 
£  is  performed  in  the  expression  which  Professor  Kelland 
quotes  (p.  268)  from  M.  Cauchy,  the  result  ought  to  be  in- 
dependent of  the  position  of  the  wave's  front ;  and  so  it  is 
proved  either  that  my  equations  and  M.  Cauchy's  are  identical, 
or  that  M.  Cauchy's  are  at  variance  with  experiment.  The 
methods  by  which  we  have  obtained  our  equations  are  perfectly 
dissimilar,  but  I  believe  the  equations  themselves  are  identical. 
In  deducing  his  M. Cauchy  has  adhered  closely  to  theoretical 
considerations  ;  but  in  deducing  mine,  I  have  proceeded  to  a 
certain  point  by  the  guidance  of  theory,  and  then  beginning 
from  a  more  advanced  point,  where  the  results  of  experiment 
were  known,  have  worked  backwards  to  meet  theory.  It  is 
therefore  easily  seen  that  my  results  being  a  mixture  of  theory 
and  experiment  would  not  present  the  same  appearance  to  the 
eye  as  the  results  of  M.  Cauchy,  which  are  obtained  from 
theory  alone.  They  must,  however,  be  identical  in  fact,  or 
else  theory  is  discordant  with  experiment.  What  therefore 
Professor  Kelland  has  written  (p.  268)  about  "  the  axis  of 
transmission"  is  grounded  on  a  misconception,  from  which 
also  has  sprung  his  idea  that  "  the  form  of  my  equations  " 
(p.  46),  from  which  my  inferences  have  been  drawn  against  the 
Newtonian  law,  &c,  "  does  depend  on  the  position  of  the  front 
of  the  wave." 

I  believe  I  have  now  replied  to  every  objection  of  import- 
ance which  Professor  Kelland  has  brought  forward ;  I  cannot 
however  conclude  this  letter  without  remarking,  that  it  is  ob- 
vious that  a  discussion  like  the  one  in  which  we  are  now  en- 
gaged never  can  be  brought  to  a  satisfactory  conclusion  un- 
less both  parties  write  with  perfect  candour  and  a  single  eye  to 
the  discovery  of  the  truth.  All  arguments  which  do  not  really 
bear  upon  the  Newtonian  law  must  be  avoided ;  and  those 
which  do  bear  upon  it,  if  after  due  scrutiny  they  be  found  to 
be  true,  unhesitatingly  admitted  with  all  their  consequences. 
I  would  therefore,  with  a  view  of  shortening  our  labours,  re- 
spectfully request  the  Professor  not  to  take  so  wide  a  field, 
but  to  confine  himself  to  the  prominent  and  really  important 
points  of  the  argument ;  because  if  objections  of  this  character 
cannot  be  answered,  it  is  clearly  quite  unnecessary  for  him  to 
descend  with  M.  Cauchy  into  the  mystical  and  doubtful  sub- 
tilties  of  "refined  analysis."  May  I  then  respectfully  re- 
quest the  Professor  to  answer  in  the  spirit  here  recommended 
the  four  following  queries,  which  seem  to  me  better  calculated 
than  any  others  to  bring  our  discussion  to  a  speedy  termina- 
tion?— 


444      Dr.  Booth  on  a  Theorem  in  Analytical  Geometry, 

1.  Does  Professor  Kelland  admit  that  I  have  satisfactorily 
proved  that  the  quantity  n  used  in  his  memoir  on  dispersion 
is  equal  to  zero? 

2.  Does  he  admit  that  the  evanescence  of  that  quantity 
destroys  his  equations  of  motion  ? 

3.  Does  he  admit  that  the  evanescence  of  his  equations  of 
motion  destroys  his  proof  of  the  transversality  of  vibrations  ? 

4.  Does  he  admit  that  the  disappearance  of  his  equations  of 
motion  in  a  medium  of  perfect  symmetry  whenever  Newton's 
law  is  introduced,  is  a  sufficient  proof  that  that  cannot  be  the 
law  of  molecular  action  ? 

If  he  does  admit  these  points  our  discussion  is  at  an  end ; 
but  if  he  does  not,  I  shall  with  great  willingness  answer  any 
objections  against  these  which  he  may  think  it  necessary  to 
bring  forward.  The  introduction  of  collateral  questions  (such 
as,  "  whether  the  force  acts  by  attraction  or  repulsion," 
"  whether  a  cubical  arrangement  is  or  is  not  one  of  geometric 
symmetry,"  "  whether  the  aether  has  boundaries,"  "  how  vi- 
brations are  generated,"  "  whether  it  is  probable  that  a  vio- 
lent effort  would  be  requisite  to  move  a  particle  of  aether  out 
of  its  position  of  equilibrium,"  and  others  of  a  similarly  dis- 
cursive nature  which  the  Professor  has  mooted  in  his  letters) 
tends  unnecessarily  to  distract  attention  from  the  main  ques- 
tion ;  they  may  therefore  safely  be  allowed  by  both  parties  to 
stand  over  as  unimportant  till  all  objections  which  are  of  the 
first  magnitude  have  been  refuted  or  allowed. 

Cambridge,  Oct.  7,  1842. 


H 


LXXVIII.     On  a  Theorem  in  Analytical  Geometry. 
By  the  Rev.  James  Booth,  LL.D.,  M.R.I.  A. 
[Continued  from  p.  179.] 
AVING  shown  that  if  three  fixed  points  assumed  on  a 
ri«*ht  line  are  always  retained  in  three  fixed  planes,  any 
fourth  point  P  will  describe  an  ellipsoid,  whose  centre  is  the 
common    intersection    of  the   three  planes,   we   proceed  to 
establish  the  following  remarkable  property,  that  the  volume 
of  this  ellipsoid  is  independent  of  the  angles  between  the  co- 
ordinate axes ;  a  singular  result,  to  which  an  analogous  pro- 
perty may  be  found  in  the  ellipse. 

Resuming  the  equation  found  at  page  1 78, 

x2      Iv2       z2       2  cos  \  2  cos  u.  2  cos  v 

When  the  equation  of  the  ellipsoid  is  in  this  form,  having  all 
its  terms  positive,  the  point  P  is  supposed  to  be  external  to 


Dr.  Booth  on  a  Theorem  in  Analytical  Geometry.       445 

the  three  fixed  points ;  on  the  contrary,  when  P  is  between 
any  two  of  the  points,  the  corresponding  pair  of  rectangles 
become  negative. 

To  determine  the  volume  of  this  surface,  let  U  =  0 ,  be  the 
equation  of  a  sphere,  whose  radius  is  r,  referred  to  the  same 
oblique  axes  of  coordinates,  having  its  centre  at  the  origin, 
and  touching  the  ellipsoid  at  one  of  its  vertices;  then  if  a 
tangent  plane  to  the  ellipsoid  be  drawn  at  this  point,  it  will 
also  touch  the  sphere,  and  we  shall  consequently  have,  the 
equation  of  the  sphere  being 

U  z=:x2+y'1+z--\-2yzcos'A-\-2xzcos  p+2  xy  cos  »— r2  =  0    (3.) 

dV      dXJ      dV      dV      dV      dV 


dz  "     dz9 


(4.) 


dx       doc         dy        dy' 

as  the  coefficients  of  the  variables  in  the  equations  of  the  co- 
incident tangent  planes  are  identical;  hence 


x         y  z  x  +  y  cos  v  +  z  cos  a  ■ 

-3-  +  -^tCOSV  H COSjU.  =  - a - 

a2       ab  ac       ~  r2 


y         2  x 

■To  +  T~  cos  A  H t-  COS  V 

b2       be  ab 

Z  CO  7/ 

-a  H cosa  +  -f-  COS  A  = 

cz       ac      ^      be 


or  putting  t  —  — ,  w  =  ^-,  there  results 


y  +  z  cos  A  +  x  cos  v   .    .  ,  -  \ 

** 9 >  '    \5') 


z  4-  x  cos  ju,  +  y  cos  A 


a 


t  t  COSfX.         COS  |U<  __  t   +  u  COS  V  +  COS  jU. 

"I  t      ~      r 


a  b 


a  c 
cos  A 


u       t  cos  v 

b2         ab  be 


u  +  t  cos  v  4-  cos  A 


1  tfCOSjX       wcosA  _  1  +  ICOSfl  +  mcosA 

h  ~b~c~  +  ~bc~~~ 


(6.) 


cf  o  c  oc  tr 

From  these  equations,  eliminating  t  and  w,  we  find  the  cubic 
equation,  putting 

1  —  cos2  A  —  cos4  ft  —  cos3  v  +  2  cos  A  cos  ft  cos  v  =  A2, 

r6  ~r!  [Vsin2  X  +  42 sin2 fi  +  c2  sin2  v  -  (b  c  cos2  X  +  a  c  cosV  +  a  i  cos2  i>) 
+  2(ab  +  ac-\-  b  c)  cos  Xcos  /x  cos  vl 

-(-L.rjVsin2\  +  a2c2sin2u4-a2J2sin2j/  -  aftc(acos2X  +  b  cos- p -\- c  cos*  v) 


4-  2  a  i  c  (a  +  ft  +  c)  cos  X  cos  /t  cos  v~\ 

-a36V  =  0    .    . 


(7.) 


446        Notices  of  the  Labours  of  Continental  Chemists. 

Now  the  squares  of  the  three  semiaxes  of  the  surface  are  the 
three  roots  of  this  cubic  equation,  and  as  the  last  term  is  the 
product  of  the  roots  with  the  sign  changed,  we  find,  calling 
the  semiaxes  r1  r"  r1", 

r1  r"  r1"  =  a  b  c, 

hence  the  volume  of  the  ellipsoid  =  — -  r'  r"  r"1  =  —  a  b  c. 

r  3  3 

It  is  not  difficult  to  show,  that  the  areas  of  the  sections  of  the 
surface  made  by  the  coordinate  planes  are  it  a  b,  irac,  and 
it  be  respectively,  and  in  general  that  the  area  of  any  conic 
section  whose  equation  is 

A2.r2+  BV  +  2ABcosv.#y  =  1, 
is  independent  of  v,  the  angle  between  the  axes  of  coordinates, 
where  A  and  B  are  the  reciprocals  of  the  segments  into  which 
the  line  moving  between  the  axes  of  coordinates  is  divided. 

From  this  known  property  that  if  a  line  of  constant  length 
revolves  between  two  fixed  rectangular  axes,  the  locus  of  the 
middle  point  is  a  circle,  may  be  deduced  a  method  of  con- 
verting rectilinear  into  circular  motion,  rigorously  exact,  and 
simple  in  construction,  admitting  an  unlimited  length  of 
stroke,  and  obviating  the  necessity  of  using  a  working  beam 
or  connecting  rod  ;  a  change  which  would  introduce  a  de- 
cided improvement  in  the  construction  of  the  steam-engine*. 

LXXIX.  Notices  of  the  Results  of  the  Labours  of  Continental 
Chemists.  By  Messrs.  W.  Francis  and  H.  Croft. 
[Continued  from  p.  287.] 
On  Hematoxylin. 
/^HEVREUL  examined  Campechy  wood  (wood  ofHatma- 
^-/  toxylin  campechianum,  L.)  thirty  years  ago,  and  found  in 
it  a  crystallizable  colouring  principle  which  he  called  Haematin, 
which  name  has  been  changed  into  Haematoxylin  to  avoid 
any  confusion  with  the  heematin  of  the  blood.  Chevreul  pro- 
bably did  not  procure  the  body  in  a  state  of  purity.  Erdmann 
has  now  examined  it,  and  he  proposes  the  following  method 
for  its  preparation: — The  common  extract  of  logwood  is  pul- 
verized and  mixed  with  a  considerable  quantity  of  pure  sili- 
ceous sand  (to  prevent  the  agglutination  of  the  particles  of  the 
extract),  and  the  whole  allowed  to  stand  several  days  with  five 
or  six  times  its  volume  of  aether,  the  mixture  being  often 
shaken ;  the  clear  solution  is  poured  off  and  distilled  until 
there  is  only  a  small  syrupy  residue.     This  is  mixed  with  a 

*  [The  reader  is  requested  to  cotrect  some  oversights  and  errors  in  the 
preceding  part  of  this  paper,  it  having  been  printed  from  an  unrevised  proof. 
— Edit.] 


Erdmann  on  Hematoxylin.  447 

certain  quantity  of  water  and  allowed  to  stand  for  some  days, 
when  the  hsematoxylin  crystallizes  out,  and  may  be  pressed 
between  bibulous  paper,  &c.  The  residual  extract  itself  con- 
tains more  of  the  substance ;  from  2  pounds  of  extract  treated 
with  10  pounds  of  aether,  Erdmann  obtained  between  3  and  4 
ounces  of  hematoxylin. 

The  colour  of  haematoxylin  varies  from  a  straw  yellow  to  a 
deep  yellow ;  when  pulverized  it  is  white  or  pale  yellow.  The 
crystals  can  be  obtained  some  lines  in  length  ;  their  form  has 
been  studied  by  Wolff  and  previously  byTeschemacher  (Phil. 
Mag.  S.  3.  p.  28).  It  tastes  like  liquorice  root  without  any 
trace  of  bitterness  or  astringency.  Chevreul  describes  it  dif- 
ferently, but  he  probably  had  an  impure  substance. 

Haematoxylin  dissolves  slowly  in  cold  water,  but  very  easily 
in  boiling  water.  It  is  necessary  to  employ  water  which  has 
been  previously  boiled,  for  the  smallest  possible  trace  of  am- 
monia causes  the  haematoxylin  to  become  purple,  and  Erd- 
mann proposes  this  substance  as  the  most  delicate  test  for 
ammonia :  pure  oxygen  or  air  freed  from  ammonia  does  not 
alter  the  colour.  The  crystals  must  be  dried  by  pressure  in 
bibulous  paper.  The  filtering  paper  which  is  used  for  the 
solutions  of  haematoxylin  must  be  free  from  lime.  Haema- 
toxylin is  soluble  in  alcohol  and  aether,  but  the  solution  in 
anhydrous  aether  does  not  yield  crystals.  By  exposure  to 
sunlight  the  substance  acquires  a  reddish  colour,  but  no  change 
in  its  constitution  is  effected. 

It  does  not  sublime,  leaves  behind  a  great  quantity  of  char- 
coal when  heated  in  a  tube ;  does  not  evolve  ammonia  when 
heated  with  potassa,  and  consequently  contains  no  nitrogen. 
This  haematoxylin  loses  water  at  ordinary  temperatures, 
and  the  desiccation  is  completed  at  100-120°  C. ;  it  contains  3 
atoms  of  water,  its  formula  is  therefore  C40  H34  015+8  H2  O. 
Another  hydrate  containing  only  3  atoms  of  water  is  ob- 
tained by  allowing  a  hot  saturated  solution  of  haematoxylin 
to  cool  in  a  closed  vessel,  when  it  separates  in  small  granular 
crystals.  It  was  impossible  to  determine  the  atomic  weight  of 
the  body. 

Caustic  potassa  colours  a  solution  of  haematoxylin  violet, 
but  by  absorption  of  oxygen  the  colour  passes  into  purple, 
brownish  yellow,  and  at  last  dirty  brown.  These  compounds 
appear  to  contain  haematoxylin  in  different  degrees  of  oxida- 
tion. 

Ammonia  has  the  same  effect,  but  the  presence  of  air  is 
necessary  to  effect  the  change  fully ;  the  ammoniacal  solution 
becomes  deep  red,  almost  black.  If  acetic  acid  be  added  to 
this  solution  until  a  precipitate  begins  to  be  formed,  and  it  be 


448         Notices  of  the  Labours  of  Continental  Chemists. 

then  evaporated,  the  ammonia  being  carefully  replaced  from 
time  to  time  (excess  is  to  be  avoided),  a  compound  crystallizes 
out  in  dark  violet  grains  which  contains  ammonia  combined 
with  Htematein ;  these  crystals  must  be  quickly  filtered  off  and 
dried  by  pressure  and  exposed  to  the  air,  but  heat  must  not  be 
employed.  The  mother  liquor  may  be  precipitated  by  means 
of  acetic  acid,  haematein  falls  down  in  the  form  of  an  ochre- red 
voluminous  body  like  hydrated  sesquioxide  of  iron;  when  dried 
it  is  dark  green  with  a  metallic  glance,  red  by  transmitted 
light;  the  powder  is  red.  Slowly  soluble  in  cold,  easier  in  boiling 
water.  Soluble  in  alcohol  with  a  reddish  brown  colour,  very 
little  soluble  in  aether;  dissolves  in  potassa  with  a  blue  co- 
lour, which^exposed  to  the  air  passes  through  red  into  brown  ; 
with  ammonia  it  gives  a  purple  solution  which  soon  turns  into 
brown;  formula  C40  H30  O16.  Haematoxylin  absorbs  3  atoms 
of  oxygen  under  the  influence  of  ammonia,  and  forms  haema- 
tein, and  2  atoms  of  water,  C40  H34  O15  +  O3  =  C40  H30 
016+H402. 

No  carbonic  acid  is  formed  during  the  change. 

Haematein-ammonia  is  a  bluish-black  or  rather  violet-black 
powder,  which  under  the  microscope  is  seen  to  consist  of 
quadrilateral  prisms.  It  is  soluble  in  water  with  an  intense 
purple  colour,  with  alcohol  it  gives  a  reddish-brown  solution. 
Heated  to  100°  C.  it  loses  water  and  ammonia,  it  must  there- 
fore be  dried  over  sulphuric  acid.  When  dry  it  does  not 
decompose  of  itself,  but  if  moist  or  in  solution  a  spontaneous 
decomposition  takes  place.  '  Formula  C40  H44  N4  Oi7 ;  con- 
sequently 1  atom  of  haematein  takes  up  2  atoms  of  ammonia 
and  1  atom  of  water.  Erdmann  gives  the  ammonia  com- 
pound the  formula  C40  H28  O15  +  2  N2  H8  O,  and  haematein 
C40  H28  O15  +  H2  O. 

Haematein-ammonia  gives  coloured  precipitates  with  most 
metallic  solutions.  The  lead  compound  is  blue,  but  it  is  basic, 
for  the  supernatant  solution  is  acid ;  at  first  the  washings  are 
colourless,  but  soon  become  brown-coloured :  it  is  probable 
that  under  the  influence  of  oxide  of  lead,  air  and  moisture, 
the  haematein  undergoes  slow  oxidation  and  decomposition. 
The  blue  compound  was  washed  a  little  and  then  analysed : 
the  organic  part  of  it  agreed  pretty  well  with  the  formula 
C40  H28  O15. 

A  reddened  solution  of  haematoxylin  is  decolorated  by 
sulphuretted  hydrogen,  and  on  evaporation  pure  haematoxylin 
is  obtained ;  a  solution  of  haematein  is  also  rendered  colour- 
less by  sulphuretted  hydrogen,  but  in  this  no  reduction 
takes  place,  for  on  evaporating,  as  the  gas  is  driven  off  the 
solution  acquires  its  original  dark  colour,  and  crystals  of  hae- 


Opianic  Acid — Quinoiline.  449 

matein  are  formed,  but  not  a  trace  of  hsematoxylin.  It  is 
evident,  therefore,  that  the  sulphuretted  hydrogen  enters  into 
combination  with  haematein,  as  Chevreul  has  already  stated. 
The  lead  and  copper  compounds  of  haematein  were  also  treated 
with  sulphuretted  hydrogen,  but  in  no  case  was  any  reduction 
visible.  A  few  experiments  were  made  on  the  action  of  nas- 
cent hydrogen,  which  appeared  to  have  better  success. — (Journ. 
fur  Prakt.  Chemie,  vol.  xxvi.  p.  193.) 

Opianic  Acid. 

Liebig  and  Wohler  have  discovered  that  this  body  is  pro- 
duced when  narcotine  is  exposed  to  oxidizing  agencies.  It  is 
best  prepared  in  the  following  manner: — Narcotine  is  dissolved 
in  a  considerable  excess  of  dilute  sulphuric  acid,  finely  pow- 
dered peroxide  of  manganese  is  added,  and  the  whole  heated : 
it  soon  begins  to  assume  a  saffron-yellow  colour  and  to  evolve 
carbonic  acid.  It  must  be  heated  to  boiling,  and  this  tem- 
perature maintained  as  long  as  carbonic  acid  is  evolved.  At 
the  end  of  the  operation  there  must  still  be  excess  of  oxide  of 
manganese  and  sulphuric  acid.  It  is  filtered  while  hot ;  the 
liquid  on  cooling  forms  a  mass  of  fine  acicular  crystals;  these 
must  be  washed  with  cold  water,  and  purified  by  re-solution 
in  water  and  decoloration  with  animal  charcoal.  Opianic 
acid  crystallizes  in  fine  silky  needles,  whose  form  cannot  be 
determined.  Soluble  in  hot  water  but  not  in  cold.  Soluble 
in  alcohol.  Acts  as  an  acid,  but  has  only  a  weak  bitter  sourish 
taste.  Fuses  easily  into  an  oil  which  crystallizes  on  cooling, 
but  if  the  temperature  has  been  raised  above  its  fusing  point, 
it  remains  amorphous.  Is  not  volatile.  Heated  in  the  air  it 
gives  off  the  same  aromatic  odouras  narcotine;  it  inflames  easily, 
and  burns  with  deposition  of  soot. 

It  expels  carbonic  acid  from  its  salts,  and  forms  soluble 
compounds  with  all  bases ;  does  not  contain  nitrogen.  Lie- 
big  and  Wohler  are  at  present  engaged  in  its  more  accu- 
rate examination.  —  (Journ.  fur  Prakt.  Chem.  vol.  xxvii. 
p.  97.) 

Quinoiline. 

Gerhardt  boiled  one  part  of  quinine  with  four  parts  of  po- 
tassa  and  one  of  water  in  a  small  retort;  the  mixture  became 
brown,  and  a  heavy  yellow  oil  passed  over  with  the  water. 
Hydrogen  is  evolved  during  the  process.  If  the  potassa  is 
not  allowed  to  fuse  and  the  water  continually  replaced,  no 
ammonia  is  formed.  The  oil  is  evidently  alkaline,  and  forms  cry- 
stallizable  salts  with  acids ;  with  bichloride  of  platinum  it  pro- 
duces a  compound  soluble  in  boiling  water,  which  on  cooling 
crystallizes  in  golden-yellowneedles.  Itsformulais  C10'H22  N2  0% 

Phil.  Mag.  S.  3.  Vol.  21.  No.  140.  Dec.  1842.    2  H 


450       Notices  of  the  Labours  of  Continental  Chemists. 

H2  CI2  +  Pt  CI4.  Consequently  one  atom  of  quinine,  by  taking 
up  four  atoms  of  water  and  giving  off  C4  O4  produces  two 
atoms  of  quinoiline.  This  base  also  forms  a  crystalline  double 
salt  with  bichloride  of  mercury.  New  liquid  bases  are  also 
produced  by  acting  with  potassa  on  strychnine,  narcotine,  &c, 
but  the  process  is  more  complex. 

On  Indigo-Nitric  Acid  (Indigotic  Acid). 

Marchand  instituted  a  series  of  experiments  on  this  acid 
with  a  view  to  determine  its  composition,  without  being  aware 
that  Dumas  was  engaged  on  the  subject:  Marchand's  results 
have  now  been  published,  and  they  agree  with  those  already 
obtained  by  Dumas.  He  found  the  crystallized  acid  to  con- 
tain three  atoms  of  water,  two  of  which  are  given  off  at  150°  C, 
or  by  long  exposure  to  a  dry  atmosphere.  The  third  atom 
is  only  displaced  by  bases.  The  formula  of  the  hydrated  acid 
is  C14  H8  N2  O9  +  3  H2  O.  The  ammonia  salt  is  anhydrous, 
as  is  also  the  silver  salt.  Neutral  indigo-nitrate  of  baryta  was 
obtained  by  boiling  the  acid  with  carbonate  of  baryta;  it  forms 
shining  needles  which  are  difficultly  soluble  in  cold  water, 
insoluble  in  alcohol  and  aether.  It  explodes  when  heated  ;  it 
contains  five  atoms  of  water,  of  which  it  loses  four  at  200°  C, 
By  boiling  with  caustic  baryta  or  by  the  addition  of  ammonia 
a  basic  salt  is  obtained.  It  contains  two  atoms  of  base  and 
five  of  water.  The  potassa  salt  is  anhydrous.  The  formula 
of  the  indigo-nitric  acid  has  a  great  resemblance  to  those  of 
the  salicyle  series.  Marchand  endeavoured  to  trace  the  con- 
nexion, and  in  the  first  place  analysed  some  of  the  primary 
compounds,  because  it  was  possible  that  the  new  atomic  weight 
of  carbon  might  make  some  difference  in  their  constitution. 
His  analyses  of  salicine,  as  well  as  those  of  Piria,  Mulder, 
Otto  and  Erdmann,  agree  very  closely  with  the  formula 
C28  H38  O15,  which  explains  the  decompositions  in  a  very 
satisfactory  manner;  the  formation  of  salicylous  acid  (hydu- 
ret  of  salicyle)  is  very  simple,  C28  H38  O15  =  2  (C14  H12  O4) 
+  7  H2  O.  Gerhardt  has  remarked  that  traces  of  salicylous 
acid  are  formed  among  the  products  of  the  simple  distillation 
of  salicine ;  this  method  of  preparing  it  is  not,  however,  advan- 
tageous, inasmuch  as  very  little  is  obtained.  The  best  process 
is  that  of  Piria  as  modified  by  Ettling.  Three  parts  bichromate 
of  potassa,  three  parts  salicine,  four  parts  and  a  half  sulphuric 
acid,  and  thirty-six  water.  After  twenty  parts  have  passed 
over,  twenty  parts  of  water  may  be  added  and  again  distilled 
off.  Marchand  confirmed  Piria's  formula  lor  salicylous  acid, 
viz.  C14  H12  O4.  Salicylic  acid  may  be  obtained  by  fusing 
salicylite  of  potassa  with  excess  of  potassa,  or  at  once  from 


On  the  Compounds  of  Sugar  with  Bases.  451 

salicine,  as  has  been  shown  by  Gerhardt;  by  fusing  salicine  with 
an  excess  of  caustic  potassa,  hydrogen  is  evolved ;  the  mass 
must  not  be  allowed  to  become  perfectly  white,  for  then  some 
of  the  salicylic  acid  is  decomposed.  Marchand  employed  two 
pounds  and  a  half  of  potassa  to  half  a  pound  of  salicine.  If 
too  little  potassa  is  used,  resin  and  salicylous  acid  are  pro- 
duced. Marchand  found  the  same  formula  as  Piria.  If  this 
salicylic  acid  be  mixed  with  strong  nitric  acid  the  action  is 
exceedingly  violent,  and  picrin-nitric  acid  is  produced  ;  if,  how- 
ever, it  be  treated  with  dilute  nitric  acid  the  so-called  salicylo- 
nitric  acid  is  formed,  which  Marchand  has  shown  to  be  iden- 
tical with  indigo-nitric  acid. — {Journ.fur  Prakt.  Chem.f  vol. 
xxvi.  p.  386.) 

On  the  Compounds  of  Sugar  with  Bases. 

Berzelius  determined  the  atomic  weight  of  sugar  from  the 
analysis  of  the  lead  salt,  which  he  considered  to  be  a  compound 
of  one  atom  of  sugar  with  two  atoms  of  oxide  of  lead.  Peligot 
analysed  this  salt,  and  also  the  compounds  with  baryta  and 
chloride  of  sodium,  and  from  them  he  deduced  C24  H36  O18 
as  the  equivalent  of  anhydrous  sugar,  which  combines  with 
four  atoms  of  base.  But  the  true  equivalent  is  not  yet  quite 
settled,  for  Berzelius  threw  out  doubts  as  to  Peligot's  correct- 
ness ;  and  the  analysis  of  the  baryta  salt,  upon  which  the  latter 
chemist  places  considerable  reliance,  has  been  called  in  ques- 
tion by  Liebig.  With  a  view  to  clear  up  these  mysteries 
Soubeiran  undertook  a  series  of  experiments  on  tlje  subject. 
As  the  compounds  are  very  difficult  to  burn,  he  employed 
chromate  of  lead  mixed  with  bichromate  of  potassa.  Sou- 
beiran found  exactly  the  same  formula  for  the  baryta  salt  as 
Peligot;  he  could  not  obtain  a  compound  containing  less 
baryta.  Brendecke  prepared  one  with  only  18*5  per  cent, 
baryta,  while  the  usual  one  contains  30  per  cent. 

Peligot  has  examined  a  combination  of  sugar  with  lime ;  he 
considers  that  it  is  always  formed  when  lime  is  brought  into 
contact  with  sugar ;  he  found  14  per  cent,  of  lime  in  it.  Daniell 
however  stated  that  he  had  obtained  a  compound  containing 
one  third  of  its  weight  of  lime,  by  boiling  fifteen  parts  of  water 
with  six  of  lime  and  ten  of  sugar  for  half  an  hour.  Soubeiran 
could  never  obtain  a  compound  with  so  much  lime ;  the  salt 
he  found  to  be  most  generally  formed  is  one  in  which  the 
proportion  of  the  ingredients  is  as  1:4;  this  is  always  pro- 
duced when  the  lime  is  in  excess,  and  the  mixture  is  boiled, 
or  else  allowed  to  stand  at  ordinary  temperatures.  Brendecke 
prepares  it  by  adding  half  a  part  of  water  to  a  mixture  of 
equal  parts  of  lime  and  sugar;  a  resinous  mass  is  formed  which 

2H2 


452         Notices  of  the  Labours  of  Continental  Chemists. 

is  dissolved  in  water.  This  salt  consists  of  C24  H44  O22  +  3  Ca  O. 
The  compound  containing  two  atoms  of  lime,  14  per  cent.,  is 
much  more  difficult  to  prepare ;  an  excess  of  sugar  must  be  used 
(sugar  thirteen  parts,  unslaked  lime  two  parts),  the  salt  must 
be  precipitated  from  its  solution  by  alcohol.  Soubeiran  could 
not  obtain  any  other  compound  of  lead  but  that  with  four 
atoms  of  base. 

The  compounds  with  potassa  and  soda  have  been  examined 
by  Brendecke,  but  are  difficult  to  procure  in  a  pure  state,  and 
are  moreover  deliquescent.  Soubeiran  did  not  make  any  ex- 
periments on  them.  From  his  researches  he  considers  the 
constitution  of  an  atom  of  sugar  to  be  C24  H36'  O18  =  S,  and 
the  salts  may  be  arranged  as  follows : — 

Crystallized  sugar  ==  S-f-4aq. 

P°comp  }  =  S+R0  Lead  comP'    =  S  +  4PbO. 

...Probably=S+  {f^O)    Lime     ...      =  S+|3  (C.O+EPO) 

Soda  =S+      Na'o  Lime      ...      =  S4  {|  ^a  °  +  H2°> 

...probably^  S+  {  f^'W0)  ^'^  %      =S+  {|^°+IP0) 
Chloride  of  sodium  l_o,    fNaCl2 
compound  J  ~~         \  3  aq. 

(Journ.  de  Pharm.  et  deChim.  Juin  1842.) 

Plumbo-Sulphate  of  Ammonia. 

Sulphate  of  lead  is  considerably  soluble  in  sulphate  of  am- 
monia, particularly  when  boiled.  A  double  salt  crystallizes 
out  on  cooling ;  the  best  method  of  obtaining  it  is  to  precipi- 
tate a  tolerably  concentrated  solution  of  acetate  of  lead  with 
excess  of  dilute  sulphuric  acid  ;  it  is  then  neutralized  with  am- 
monia, and  the  whole  boiled,  by  which  the  sulphate  is  dis- 
solved. If  this  does  not  take  place  there  is  a  want  of  sul- 
phate of  ammonia ;  if  the  solution  does  not  deposit  crystals 
on  cooling,  sulphuric  acid  must  be  added  until  turbidness 
commences.  It  appears  as  if  the  salt  were  easier  formed  when 
acetate  of  ammonia  is  present.  The  double  salt  forms  small, 
but  bright  well-defined  crystals.  It  is  decomposed  by  water, 
and  also  by  heat,  when  sulphate  of  lead  and  sulphite  of  am- 
monia are  formed  :  the  latter  salt  sublimes.  It  does  not  con- 
tain water  of  crystallization.  According  to  the  analysis  of 
Professor  Litton,  its  formula  is  Pb  O,  S  03+  N2  H8  O,  S  O3. 
— (Ann.der  Chem.  und  Ph.,  vol.  xliii.  p.  126.) 


[     453     ] 

LXXX.  On  a  ?iew  Imponderable  Substance,  and  on  a  Class  of 
Chemical  B,ays  analogous  to  the  Rays  of  Dark  Heat.  By 
John  William  Draper,  M.D.,  Professor  of  Chemistry  in 
the  University  of  New  York*. 

[With  F  igures,  Plate  I.] 

IN  the  Number  of  this  Journal  for  September  1841,  I  have 
pointed  out  several  analogies  which  may  be  observed  be- 
tween the  phsenomena  of  the  chemical  rays  and  those  of  ra- 
diant heat. 

In  this  communication  it  is  my  intention  to  show  still  more 
striking  points  of  analogy,  and  also  to  direct  the  attention  of 
chemists  to  equally  striking  points  of  discordance. 

It  will  be  seen  from  the  remarkable  facts  detailed  in  this 
paper,  that  we  are  now  forced  to  recognize  the  existence  of  a 
new  imponderable  agent,  analogous  in  many  of  its  properties 
to  light,  heat,  and  electricity,  yet  differing  as  much  from  them 
all  as  they  do  from  one  another. 

So  far  as  chemical  analogies  can  direct  us  there  does  not 
appear  any  thing  unphilosophical  in  the  supposition  of  the 
existence  of  many  imponderable  agents  analogous  to  those 
already  known.  The  progress  of  science  has  indeed  tended 
in  different  directions  in  the  cases  of  the  imponderable  and 
ponderable  bodies.  Among  the  former,  we  have  successively 
seen  the  agents  that  are  concerned  in  galvanic  phenomena 
and  those  of  magnetism  merged  into  electricity;  but  the 
ponderable  bodies,  especially  those  of  a  metallic  kind,  have 
greatly  increased  in  number,  though  so  far  as  their  more  ob- 
vious physical  properties  are  concerned,  the  differences  of 
many  are  almost  undistinguishable.  We  have  thus  found  it 
necessary  to  invert  the  maxims  of  the  early  cultivators  of  che- 
mistry, who  extended  the  number  of  aethereal  agents  very 
greatly,  and  believed  that  all  metals  and  other  ponderable  prin- 
ciples were  modifications  of  one  or  two  primordial  and  ele- 
mentary forms. 

Centuries  ago  it  was  discovered  that  the  sun's  light  had 
the  property  of  effecting  chemical  changes  in  bodies,  and  it 
is  stated  that  Scheele  first  noticed  that  this  property  was 
mainly  due  to  the  violet  rays.  Seebeck  observed,  that  chlo- 
ride of  silver,  exposed  to  the  spectrum,  varied  its  colour  with 
the  colour  of  the  space  in  which  it  was  held,  and  during  the 
present  century  a  very  large  amount  of  new  observations  has 
been  accumulated.  A  new  art,  Photography,  has  come  into 
existence. 

The  general  supposition  that  obtains  is,  that  the  effects  in 
question  are  due  to  the  rays  of  light  ;  hence  all  the  words  that 
*  Communicated  by  the  Author. 


454    Dr.  Draper  on  a  new  Imponderable  Substance,  and  a 

have  been  introduced  into  use  have  reference  to  that  supposi- 
tion ;  such  words  as  photography,  photology,  photometer, 
are  derived  from  this  erroneous  hypothesis,  and  lead  us  to 
confound  together  things  which  ought  to  be  kept  essentially 
distinct. 

As  it  is  the  object  of  this  paper,  and  others  which  I  am 
shortly  to  publish,  to  call  the  attention  of  chemists  to  the  ao-ent 
that  is  involved  in  photographic  results  as  a  clearly  established 
and  new  imponderable  substance,  possessing  striking  ana- 
logies with  light  and  heat,  yet  differing  as  much  from  them 
both  as  they  do  from  each  other,  I  am  induced  to  propose 
for  it  a  proper  name,  and  to  endeavour  to  establish  for  it  a 
nomenclature  that  shall  be  free  from  ambiguity  and  keep  the 
description  of  its  phsenomena  separate  from  those  of  light. 
Whilst  therefore  I  show  that  it  undergoes  radiation,  reflexion, 
refraction,  polarization,  absorption,  interference,  &c.  under  the 
laws  to  which  its  radiant  companions  light  and  heat  are  sub- 
ject, I  wish  to  claim  for  it  a  separate  and  independent  ex- 
istence, to  introduce  it  into  the  natural  family  of  imponderable 
agents,  with  light,  heat,  and  electricity.  In  that  family  it  stands 
as  the  fourth  member.  Is  there  any  reason  that  the  progress 
of  knowledge  should  not  make  known  to  us  multiplied  forms 
of  imponderable  substances  as  well  as  of  ponderable  matters? 
This  agent  differs  from  light  and  heat,  as  much  as  lead  differs 
from  zinc  or  tin. 

When  novel  effects,  brought  about  by  novel  causes,  are  met 
with,  the  purposes  of  science  require  new  corresponding  terms. 
In  the  case  of  the  chemical  rays  of  light  it  is  so.  I  have  ex- 
perienced the  need  of  a  nomenclature  of  the  kind  from  my 
earliest  experiments.  It  is  a  rule  of  which  modern  philoso- 
phers know  the  value,  that  such  names  ought  to  be  free  from 
all  attending  hypothesis  ;  for  if  this  be  not  complied  with,  it 
soon  comes  to  pass,  as  knowledge  advances,  that  terms  in- 
volving theoretical  ideas  lose  much  of  their  significance. 

The  chemical  rays  are  associated  with  the  rays  of  light, 
accompanying  them  in  all  their  movements,  originating  with 
them,  and  unless  disturbed  continuing  to  exist  along  with 
them.  But  should  a  compound  beam  like  this  fall  upon  a 
sensitive  surface,  the  chemical  rays  sink  into  it,  as  it  were, 
and  lose  all  their  force,  and  the  rays  of  light  are  left  alone. 
Photographic  results  thus  resulting  from  the  reposing  of  the 
chemical  rays  on  the  sensitive  surface  are  not  however  in 
themselves  durable,  as  will  be  shown  in  this  paper,  for  the 
rays  escape  away  under  some  new  form. 

Tithonus  was  a  beautifulyouth  whom  Aurora  fell  in  love 
with  and  married  in  heaven.  The  Fates  hadmadehim  immortal, 


Class  of  Chemical  Bays  analogous  to  the  Rays  of  Dark  Heat.  455 

but  unlike  his  bride,  in  the  course  of  events  he  became  feeble 
and  decrepit,  and  losing  all  his  strength  was  rocked  to  sleep 
in  a  cradle.  The  goddess,  pitying  his  condition,  metamor- 
phosed him  into  a  grasshopper. 

The  fact  and  the  fable  agree  pretty  well,  and  indeed  the  play- 
ful coincidence  might  be  carried  much  further.  The  powers  of 
photography,  which  bring  architectural  remains  and  the  forms 
of  statuary  so  beautifully  and  impressively  before  us,  might 
seem  to  be  prefigured  by  the  speaking  image  of  the  son  of 
Tithonus  and  Aurora  that  was  to  be  seen  in  the  deserts  of 
Egypt.  And  besides  this,  such  words  as  Tithonoscope,  Ti- 
thonometer,  Tithonography,  Tithonic  effect,  Diatithones- 
cence,  are  musical  in  an  English  ear.  In  this  paper  I  shall 
therefore  use  the  term  Tithonicity  and  its  derivatives  in  the 
same  manner  that  we  use  electricity  and  its  derivatives. 

This  communication  takes  up  the  consideration  of  three 
distinct' facts : — 

1st.  The  proof  of  the  physical  independence  of  Tithoni- 
city and  Light. 

2nd.  The  proof  of  the  physical  independence  of  Tithoni- 
city and  Heat. 

3rd.  The  proof  of  the  existence  of  dark  Tithonic  rays, 
analogous  to  the  rays  of  dark  heat.  Under  this  head  it 
will  be  shown,  that  tithonicity  like  heat  enters  transiently 
into  bodies  producing  specific  changes  on  them,  and  then 
slowly  and  invisibly  radiates  away.  And  the  physical  consti- 
tution of  the  new  class  of  rays  thus  formed  is  entirely  differ- 
ent from  that  of  rays  that  come  from  incandescent  sources ;  a 
distinction  having  a  striking  analogy  in  the  case  of  heat. 
Tithonicity  becomes  transiently  and  permanently  latent  in 
bodies. 

The  Plate  (PI.  I.),  which  accompanies  this  paper,  serves  to 
show  that  by  the  agency  of  absorbent  media  we  may  detect  the 
existence  of  tithonic  rays  in  every  part  of  the  spectrum  unac- 
companied by  light.  The  results,  there  projected,  were  ob- 
tained by  an  arrangement  such  as  that  in  Plate  I.  'fig.  1 .  From 
a  heliostat  mirror  a  a,  a  beam  of  the  sun's  light  was  thrown 
in  a  horizontal  position,  and  falling  on  a  screen  b  b,  a  portion 
of  it  passed  through  a  circular  aperture  one-fourth  of  an  inch 
in  diameter.  At  the  distance  of  ten  or  twelve  feet  it  fell  on  a 
glass  trough  c  c,  with  parallel  faces,  into  which  any  coloured 
solution  could  be  placed ;  immediately  behind  the  trough 
there  was  a  double  convex  lens  d  d,  of  three  feet  focal  length, 
and  between  them  a  second  screen fft  with  an  aperture  cor- 
responding to  the  centre  of  the  lens,  half  an  inch  in  diameter. 
Behind  the  lens  was  situated  a  prism  of  flint  glass  e,  which 


456     Dr.  Draper  on  a  new  Imponderable  Substancet  and  a 

effected  the  dispersion  of  the  incident  beam.  Now,  the  lens 
not  being  achromatic,  the  screen  /•  v  had  to  be  placed  in  an 
inclined  position  in  order  to  obtain  a  neat  spectrum-image  of 
the  hole  in  b  b,  and  this  was  attended  with  the  great  advan- 
tage of  elongating  the  total  length  of  the  spectrum,  and  there- 
fore increasing  the  measures.  In  order  to  obtain  sensitive 
surfaces  of  great  delicacy  the  silver  plates  were  first  iodized 
lightly,  and  then  exposed  to  the  vapour  of  bromine  until  they 
attained  a  full  golden  yellow. 

In  the  Plate,  the  line  No.  1,  fig.  3,  represents  the  visible  co- 
lorific spectrum;  it,  with  No.  2,  serves  as  an  index  of  com- 
parison for  all  the  others.  No.  2  represents  the  effect  of  a 
spectrum  that  has  not  undergone  the  action  of  any  absorbent 
medium  on  the  bromoiodized  plate,  the  extreme  red  tinges 
the  plate  white,  the  extreme  violet  brown,  and  all  the  inter- 
mediate space  is  of  a  rich  brownish  violet,  with  a  point  of 
maximum  action  nearly  in  its  centre.  The  numerical  sub- 
divisions commence  with  0  at  the  extreme  red,  and  are  gra- 
duated on  a  principle,  which  I  shall  explain  in  a  future 
paper,  which  makes  the  spectra  of  different  tithonographists 
comparable. 

No.  3  shows  the  spectrum  after  absorption  by  the  persul- 
phocyanide  of  iron,  and  its  corresponding  tithonograph.  This 
spectrum  is  divided  into  three  portions,  one  of  which  is  red 
and  yellow,  a  second  indigo,  and  a  third  violet.  But  the  ti- 
thonograph exhibits  an  action  far  beyond  the  extreme  red,  half 
way  through  the  dark  space  that  intervenes  in  the  middle  of 
the  spectrum,  both  ends  of  this  lower  part  projecting  into 
dark  spaces ;  whilst  the  indigo  ray,  ordinarily  so  active,  does 
not  tithonize  at  all. 

Without  going  into  a  long  descriptive  detail  of  the  com- 
parison of  different  spectras  and  their  corresponding  tithono- 
graphs,  I  shall  here  sum  up  the  results  which  may  be  gathered 
from  an  inspection  of  the  Plate. 

By  the  absorbent  action  of  the  persulphocyanide  of  iron, 
we  can  prove  the  existence  of  invisible  tithonic  rays  beyond 
the  extreme  red, — invisible  rays  corresponding  to  the  green. 
We  can  also  prove  that  the  indigo-coloured  rays  of  light 
may  exist  without  tithonic  effect. 

By  the  absorbent  action  of  neutral  chloride  of  gold,  we  can 
insulate  blue  coloured  rays  of  light  that  are  not  tithonic. 

The  green  solution  formed  by  a  mixture  of  bichromate  of 
potash,  muriatic  acid,  and  alcohol,  enables  us  to  insulate  ti- 
thonic rays  of  the  same  refrangibility  as  the  violet,  but  unac- 
companied by  any  light. 

The  solution  of  sulphate  of  copper  and  ammonia  enables 


Class  of  Chemical  Bays  analogous  to  the  Hays  of  Dark  Heat.  457 

us  to  insulate  a  visible  red  and  yellow  ray  that  are  without 
tithonic  power,  and  an  invisible  tithonic  ray  beyond  the  vio- 
let. 

The  solution  of  litmus  enables  us  to  obtain  red  and  green 
light  without  action,  and  an  invisible  tithonic  ray  corre- 
sponding to  the  violet. 

The  solution  of  bichromate  of  potash  enables  us  to  obtain 
red  and  orange  light  without  any  tithonic  effect. 

Such  results  might  be  multiplied  without  end,  for  indeed 
there  is  scarcely  an  instance  in  which  spectra  of  rays  that 
have  passed  absorbent  media  are  exactly  coincident  with  their 
corresponding  tithonographs.  To  set  the  matter  plainly  be- 
fore the  reader,  the  following  tabular  view,  gathered  from  the 
Plate,  may  suffice. 


Name  of  Solution. 

Colour  of  Light 
without  Tithonic 
effect. 

Invisible    Tithonic 

rays    corresponding 

in  refrangibility  to  the 

Persulphoeyanide  of  iron 

Extreme  red,  green. 

Violet. 

Extreme  violet. 
Violet. 

Blue. 

Sulph.  cop.  and  ammonia 

Red,  orange. 

Bichromate  of  potash  ... 

From  this,  therefore,  I  infer  the  entire  independence  through- 
out the  spectrum  of  the  luminous  rays  that  give  to  the  organs  of 
vision  the  impression  of  colour,  and  the  tithonic  rays. 

When  I  come  to  describe  the  dark  tithonic  rays  that  are 
analogous  to  the  rays  of  dark  heat,  and  which  are  unaccom- 
panied by  any  kind  of  light  whatsoever,  no  further  doubt  can 
be  entertained  on  this  subject.  I  have  also  some  other  proofs 
of  a  very  remarkable  kind,  to  be  described  hereafter,  drawn 
from  the  phaenomena  exhibited  by  tithonic  rays  that  have  un- 
dergone polarization. 

Next,  as  to  the  independence  of  these  rays  and  the  rays  of 
heat. 

One  of  the  most  striking  proofs  of  this  is  the  facility  with 
which  impressions  of  the  moon's  disc  may  be  obtained  on  Da- 
guerreotype and  other  sensitive  plates.  Even  with  lenses  of 
comparatively  small  diameter,  and  in  the  space  of  a  few  mi- 
nutes, strong  impressions  of  the  moon's  surface  may  be  taken. 
There  is  no  more  difficulty  in  obtaining  these  sketches  than 
there  is  in  copying  a  building  or  a  statue,  or  any  other  object 
on  which  the  sun  is  shining.  But  the  moonbeams  have  hitherto 
given  no  trace  of  the  presence  of  heat. 

I  found,  moreover,  by  direct  trial,  that  plates  which  had 


458    Dr.  Draper  on  a  new  Imponderable  Substance,  and  a 

been  carefully  prepared  so  as  to  be  exceedingly  sensitive,  were 
unaffected  by  the  radiant  heat  of  copper  at  any  temperature 
up  to  a  red  heat.  These  dark  rays  therefore  have  no  kind  of 
effect  on  such  surfaces.  A  sensitive  plate  may  be  made  so  hot 
that  it  cannot  be  touched,  yet  its  surface  remains  unchanged, 
and  even  the  radiant  heat  emitted  by  brightly  incandescent 
bodies  has  no  effect,  as  I  also  proved. 

Lastly, — Proof  of  the  existence  of  dark  tithonic  rays 
analogous  to  the  rays  o/'dark  heat. 

The  experiments,  now  to  be  described,  were  made  with  Da- 
guerreotype plates  iodized  at  first  to  a  pale  lemon  yellow,  then 
brought  to  a  golden  hue  by  immersion  in  the  vapour  of  bro- 
mine, and  lastly  exposed  for  a  short  time  to  the  vapour  of 
iodine  again. 

Having  exposed  such  a  plate,  fig.  2,  a  b,  to  the  action  of 
weak  daylight  or  lamplight  for  a  period  of  time  which  would 
cause  it  to  whiten  powerfully  all  over  if  placed  in  the  vapour 
of  mercury,  carry  it  into  a  room  which  is  totally  dark,  and 
suspend  at  a  distance  of  one-eighth  of  an  inch  from  its  surface 
a  metallic  screen  c  d,  the  under-surface  of  which  is  blackened. 
Let  all  remain  in  the  dark  four  or  five  hours,  and  then  re- 
move the  sensitive  plate  a  b,  and  expose  it  to  the  vapour  of 
mercury.  All  that  portion  of  it  which  was  not  covered  by  the 
screen  c  d,  will  undergo  no  change,  but  that  which  was  be- 
neath c  d  will  whiten  powerfully. 

From  this  remarkable  result  I  infer,  that  the  tithonicity 
that  had  originally  disturbed  the  surface  of  the  plate  equally 
all  over,  has  escaped  away  from  those  portions  that  were  un- 
covered ;  but  that  its  escape  has  been  entirely  prevented  by 
the  action  of  the  screen ;  and  this  must  be  through  radia- 
tion, for  the  screen  is  at  a  distance  and  has  never  touched 
the  plate.  And,  further,  that  the  rays  that  do  thus  escape 
away  are  absolutely  invisible  to  the  eye. 

Now,  suppose  a  piece  of  black  cloth,  placed  in  the  rays  of 
the  sun  until  it  has  become  warm,  were  carried  into  a  cold 
room  and  half  its  surface  screened  by  some  material,  as  a  piece 
of  glass,  at  a  short  distance ;  there  cannot  be  a  doubt  that  the 
uncovered  portion  would  cool  fast  by  radiation,  but  the  screen- 
ed portion  more  slowly,  for  its  radiation  would  be  arrested  by 
the  glass  plate. 

The  two  cases  are  absolutely  alike. 

Tithonicity  therefore  radiates  exactly  after  the  manner  of 
heat. 

This  also  furnishes  proof,  in  addition  to  those  I  have  here- 
tofore given  in  this  Journal,  that  not  only  does  tithonicity  be- 
come latent  in  bodies,  but  that  it  becomes  latent  in  two 


Class  of  Chemical  Rays  analogous  to  theRays  of  Dark  Heat.  459 

ways,  transiently  and  permanently,  exactly  after  the  manner 
of  heat. 

The  same  result  is  obtained  when  other  sensitive  surfaces 
are  employed,  the  period  of  time  differing  for  different  bodies. 
Guided,  therefore,  by  the  analogy  of  heat,  I  perceive  that  bo- 
dies have  a  relation  to  this  imponderable  agent  corresponding 
to  that  of  specific  heat.  It  follows  therefore  with  certainty  that, — 
The  specific  tithonicity  of  bodies  is  the  prime  function  on 
which  their  sensitiveness  depends.  Under  this  point  of  view 
the  sensitiveness  is  inversely  as  the  specific  tithonicity. 

The  circumstances  under  which  this  experiment  is  made 
serve  also  to  show  that  metallic  bodies  are  non-conductors  of 
tithonicity. 

This  contrasts  remarkably  with  their  action  towards  heat. 
Having  exposed  a  sensitive  plate  a  b  to  light  until  it  would 
whiten  if  mercurialized,  as  before ;  and  having  prepared  a  se- 
cond, c  d  (fig.  2),  in  total  darkness,  without  allowing  any  light 
to  have  access  to  it,  suspend  this  latter  over  the  former  at  the 
distance  of  one-eighth  of  an  inch,  so  as  to  cover  it  about  half. 
Keep  the  two  plates  in  darkness  for  several  hours  and  then 
mercurialize  both.  That  portion,  a  c,  of  the  first,  not  covered 
by  the  second,  will  not  whiten ;  that  portion  of  the  second,  b  d, 
not  covered  by  the  first,  will  also  remain  unchanged ;  but  both 
on  those  parts  that  have  looked  towards  each  other  will  whiten. 
From  this  I  infer,  that  the  portion  of  the  first  not  over- 
shadowed by  the  second  does  not  whiten  because  its  tithoni- 
city escapes  away  under  the  form  of  dark  tithonic  rays. 

I  also  infer,  that  as  both  plates  are  nearly  equally  whitened 
on  those  portions  of  their  surfaces  that  have  looked  towards 
each  other,  the  dark  tithonic  rays  that  have  escaped  from  the 
first  plate,  notwithstanding  their  invisibility,  have  retained  their 
peculiar  chemical  force,  and  have  affected  the  second  plate. 

The  analogy  with  heat  is  here  perfectly  observed.  A  hot 
non-conducting  plate,  set  partially  opposite  a  cold  one,  would 
warm  that  plate  on  the  portion  looking  towards  it,  and  through 
the  consequent  retardation  of  radiation  would  retain  its  own 
heat  to  a  certain  extent.  But  all  those  portions  unopposed  by 
the  cold  plate  would  cool  down  by  radiation  rapidly. 

This  experiment  proves  in  a  clear  and  undoubted  manner 
the  total  physical  independence  of  tithonicity  and  light. 

Hence  the  absolute  necessity  of  some  such  nomenclature 
as  that  proposed, — the  chemical  rays  of  light  is  a  misnomer. 
On  the  surface  of  a  sensitive  plate  that  has  been  suitably 
exposed,  as  heretofore,  place  a  fragment  of  perfectly  clean  and 
colourless  glass.  Allow  it  to  remain  there  for  four  or  five 
hours  in  a  dark  room,  then  mercurialize,  and  it  will  be  found 


460     Dr.  Draper  on  a  new  Imponderable  Substance,  and  a 

that  the  portion  on  which  the  glass  has  been  placed  will  whiten 
powerfully,  but  all  the  rest  will  remain  unchanged. 

This,  therefore,  proves  that  colourless  glass  is  nearly  opake 
to  the  dark  tithonic  rays,  a  result  observed  also  in  the  case  of 
the  dark  rays  of  heat. 

I  made  a  comparative  trial  of  the  relative  permeability  of 
colourless  plate  glass  and  common  writing-paper.  A  sensitive 
surface  was  exposed  until  it  had  slightly  but  very  plainly  com- 
menced to  turn  brown.  On  one  portion  I  now  laid  a  piece 
of  clear  glass,  and  by  the  side  of  it  a  piece  of  writing-paper ; 
the  arrangement  was  next  placed  in  the  dark  for  four  hours; 
it  was  then  mercurialized  at  160°Fahr.  for  an  hour,  and  the 
result  was  very  striking.  Notwithstanding  the  long  exposure 
to  the  mercury  vapour,  all  those  portions  that  had  not  been 
covered  were  perfectly  unaffected,  the  portion  that  had  been 
covered  by  the  glass  was  of  an  intensely  deep  brown  colour, 
but  the  portion  covered  by  the  paper  was  marked  by  a  distinct 
but  very  faint  white  stain.  It  was  therefore  plain,  that  from 
the  uncovered  portions  all  the  tithonicity  had  radiated  away, — 
from  the  portions  covered  by  the  writing-paper  the  same  effect 
almost  to  the  same  extent  had  occurred,  the  paper,  however, 
slightly  obstructing  the  passage  of  the  rays, — but  radiation  had 
been  wholly  prevented  from  those  parts  covered  by  the  colour- 
less glass. 

Writing-paper  is  therefore  far  more  permeable  to  the  dark 
tithonic  rays  than  the  purest  plate  glass. 

This  property  it  will  be  hereafter  convenient  to  speak  of 
under  the  designation  of  Diatithonescence  or  Transtithones- 
cence. 

Blue,  red  and  yellow  glass  obstruct  to  a  great  extent  the 
process  of  radiation.  In  several  trials  it  seemed  as  though 
the  yellow  was  more  transparent  than  the  others,  but  there 
was  not  much  difference. 

Transparent  rock-salt  appears  to  hold  very  nearly  the  same 
relation  of  diatithonicity  as  plate  glass. 

In  like  manner  the  following  substances  in  thin  plates  ob- 
struct the  radiation  of  tithonicity : — Sulphate  of  lime,  beryl, 
agate,  rock-crystal,  calc-spar,  mica,  wafers,  metallic  bodies, 
cloth  of  cotton,  wood,  ivory,  coloured  glass,  &c,  &c. 

The  remarkable  results  described  in  the  Philosophical 
Transactions  by  Sir  John  Herschel  (184-0,  p.  44),  but  left 
by  him  without  any  explanation,  are  of  the  kind  now  un- 
der discussion.  He  found  that  paper  washed  with  nitrate  of 
silver,  if  exposed  to  the  sun  under  a  piece  of  glass,  darkened 
much  more  rapidly  than  if  the  glass  were  away.  This  effect 
was  by  no  means  limited  to  that  variety  of  paper,  but  was  ob- 


Class  of  Chemical  Rays  analogous  to  the  Rays  of  Dark  Heat.  46 1 

servable  also  with  many  other  tithonographic  compounds. 
Transparent  minerals,  such  as  topaz,  selenite,  Iceland  spar, 
quartz,  produced  the  same  results  as  glass.  But  on  gloomy 
days  the  phsenomena  did  not  appear,  a  bright  sunshine  being 
apparently  requisite  for  their  production.  "  When  a  piece  of 
nitrated  paper,  for  instance,  was  rolled  round  a  cylindrical 
surface  of  moderate  convexity,  covered  with  black  velvet,  and 
the  piece  of  glass  laid  gently  in  contact  with  it,  the  effect  of 
sunshine  was  exalted  at  the  line  of  contact,  but  on  either  side 
of  that  line  as  the  interval  increased  the  influence  of  the  glass 
diminished,  and  at  less  than  half  an  inch  distance  no  difference 
could  be  perceived  between  the  impressions  under  the  glass 
and  in  the  free  air." 

Now  all  this  is  precisely  what  should  happen  if  the  tithono- 
graphic compound  radiates  whilst  it  is  undergoing  decompo- 
sition. The  rays,  which  come  from  the  sun,  pass  through  the 
glass  with  but  little  loss  from  absorption,  falling  upon  the  ni- 
trate they  decompose  it,  and  now  it  commences  radiating,  but 
the  physical  character  of  these  rays  is  very  different  from  the 
character  they  possessed  before  impinging  on  the  nitrate.  Now 
they  cannot  get  through  the  glass,  before  they  passed  without 
difficulty.  So  it  is  precisely  in  the  case  of  heat.  Much  of  the 
heat  of  the  sun  passes  through  plate  glass,  and  if  it  falls  on  a 
dark  surface  that  can  absorb  it  that  surface  becomes  presently 
warm  and  commences  radiating;  but  the  physical  constitution 
of  these  rays  is  changed,  they  cannot  get  through  the  glass, 
and  if  a  non-conducting  black  surface,  half  covered  by  a  piece 
of  glass  and  half  in  the  free  air,  were  exposed  to  the  sun,  the 
covered  half  would  for  these  obvious  reasons  become  the  hotter. 
For  the  same  reason,  precisely,  in  the  tithonic  experiment  the 
glass  increases  the  final  effect  by  obstructing  radiation. 

It  is  very  obvious  why  such  effects  cannot  be  produced  on 
gloomy  days.  If  at  such  times  we  were  to  expose  a  piece  of 
black  cloth,  partially  covered  by  glass,  no  difference  of  tem- 
perature would  be  perceptible  in  its  covered  and  uncovered 
portions.     The  reasons  are  analogous  in  each  case. 

An  experiment  the  same  in  principle  as  Sir  John  HerschePs 
may  be  easily  made.  Upon  a  sensitive  plate,  that  has  been 
exposed  a  short  time  to  a  feeble  light,  place  a  convex  lens ; 
the  arrangement  being  left  for  a  time  in  a  dark  room.  When 
you  have  mercurialized,  you  will  find  a  central  dark  point 
corresponding  with  the  point  of  contact,  and  round  it  a  white 
areola  that  shades  gradually  and  imperceptibly  away.  With 
a  lens  with  which  I  have  occasionally  made  this  experiment, 
the  areola  is  nearly  an  inch  in  diameter,  the  lens  being  a 
double  convex  of  about  two  inches  focus. 


[     462     ] 

LXXXI.    On   Thermography,  or  the  Art  of  Copying  En- 
gravings, or  any  printed  Characters  from  Paper  on  Metal 
Plates ;  and  on  the  recent  Discovery  of  Moser,  relative  to  the 
formation  of  Images  in  the  Dark.      By  Robert  Hunt, 
Secretary  of  the  lloyal  Cornwall  Polytechnic  Society*. 
HPHE  Journal  of  the  Academy  of  Sciences  of  Paris,  for  the 
18th  of  July,  1842,  contains  a  communication  made  by 
M.  Regnault  from  M.  Moser  of  Konigsberg,  "  Sur  la  forma- 
tion des  images  Daguerriennest;"  in  which  he  announces  the 
fact,  that  "  when  two  bodies  are  siifficiently  near,  they  impress 
their  images  upon  each  other."     The  Journal  of  the  29th  of 
August  contains  a  second  communication  from  M.  Moser  %,  in 
which  the  results  of  his  researches  are  summed  up  in  twenty- 
six  paragraphs.     From  these  I  select  the  following,  which 
alone  are  to  be  considered  on  the  present  occasion. 

"  9.  All  bodies  radiate  light  even  in  complete  darkness. 
"  10.  This  light  does  not  appear  to  be  allied  to  phosphores- 
cence, for  there  is  no  difference  perceived  whether  the  bodies 
have  been  long  in  the  dark,  or  whether  they  have  been  just 
exposed  to  daylight,  or  even  to  direct  solar  light. 

"  10.  Two  bodies  constantly  impress  their  images  on  each 
other,  even  in  complete  darkness. 

"  14.  However,  for  the  image  to  be  appreciable,  it  is  neces- 
sary, because  of  the  divergence  of  the  rays,  that  the  distance 
of  the  bodies  should  not  be  very  considerable. 

"  15.  To  render  the  image  visible,  the  vapour  of  water, 
mercury,  iodine,  &c.  may  be  used. 

"17.  There  exists  latent  light  as  well  as  latent  heat." 
The  announcement  at  the  last  meeting  of  the  British  Asso- 
ciation of  these  discoveries  naturally  excited  a  more  than  or- 
dinary degree  of  interest.  A  discovery  of  this  kind,  changing, 
as  it  does,  the  features,  not  only  of  the  theories  of  light  adopted 
by  philosophers,  but  also  the  commonly  received  opinions  of 
mankind,  was  more  calculated  to  awaken  attention  than  any 
thing  which  has  been  brought  before  the  public  since  the 
publication  of  Daguerre's  beautiful  photographic  process. 
Having  instituted  a  series  of  experiments,  the  results  of  which 
appear  to  prove  that  these  phaenomena  are  not  produced  by 
latent  light,  I  am  desirous  of  recording  them. 

I  would  not  be  understood  as  denying  the  absorption  of 
light  by  bodies ;  of  this  I  think  we  have  abundant  proof,  and 
it  is  a  matter  well  deserving  attention.     If  we  pluck  a  Nastur- 
*  Read  at  the  Cornwall  Polytechnic  Society,  Tuesday,  Nov.  8, 1842. 
f  Comptes  Rendus,  tome  xv.  No.  3.  folio  119. 

\  Translations  of  M.  Moser's  papers  containing  the  full  details  of  his  re- 
searches and  discoveries  will  be  published  in  the  course  of  the  present  month 
(December)  in  Part  XI.  of  Taylor's  Scientific  Memoirs. 


Mr.  Hunt  on  Thermography.  463 

tium  when  the  sun  is  shining  brightly  on  the  flower,  and  carry 
it  into  a  dark  room,  we  shall  still  be  enabled  to  see  it  by  the 
light  which  it  emits. 

The  human  hand  will  sometimes  exhibit  the  same  phseno- 
menon,  and  many  other  instances  might  be  adduced  in  proof 
of  the  absorption  of  light;  and,  I  believe,  indeed  of  the  prin- 
ciple that  light  is  latent  in  bodies.  I  have  only  to  show  that 
the  conclusions  of  M.  Moser  have  been  formed  somewhat 
hastily,  being  led,  no  doubt,  by  the  striking  similarity  which 
exists  between  the  effects  produced  on  the  Daguerreotype 
plates  under  the  influence  of  light,  and  by  the  juxtaposition 
of  bodies  in  the  dark,  to  consider  them  as  the  work  of  the 
same  element. 

1 .  Dr.  Draper,  in  the  Philosophical  Magazine  for  Septem- 
ber 1 840,  mentions  a  fact  which  has  been  long  known,  "  That 
if  a  piece  of  very  cold  clear  glass,  or  what  is  better,  a  cold  po- 
lished metallic  reflector,  has  a  little  object,  such  as  a  piece  of 
metal,  laid  on  it,  and  the  surface  be  breathed  over  once,  the 
object  being  then  carefully  removed,  as  often  as  you  breathe 
again  on  the  surface,,a  spectral  image  of  it  may  be  seen,  and  this 
singular  phenomenon  may  be  exhibited  for  many  days  after 
the  first  trial  is  made."  Several  other  similar  experiments 
are  mentioned,  all  of  them  going  to  show  that  some  mysterious 
molecular  change  has  taken  place  on  the  metallic  surface, 
which  occasions  it  to  condense  vapours  unequally. 

2.  On  repeating  this  simple  experiment,  I  find  that  it  is  ne- 
cessary, for  the  production  of  a  good  effect,  to  use  dissimilar 
metals ;  for  instance,  a  piece  of  gold  or  platina  on  a  plate  of 
copper  or  of  silver  will  make  a  very  decided  image,  whereas 
copper  or  silver  on  their  respective  plates  gives  but  a  very 
faint  one,  and  bodies  which  are  bad  conductors  of  heat,  placed 
on  good  conductors,  make  decidedly  the  strongest  impressions 
when  thus  treated. 

3.  I  placed  upon  a  well-polished  copper  plate,  a  sovereign, 
a  shilling,  a  large  silver  medal,  and  a  penny.  The  plate  was 
gently  warmed  by  passing  a  spirit  lamp  along  its  under  sur- 
face ;  when  cold,  the  plate  was  exposed  to  the  vapour  of  mer- 
cury ;  each  piece  had  made  its  impression,  but  those  made 
by  the  gold  and  the  large  medal  were  most  distinct;  not  only 
was  the  disc  marked,  but  the  lettering  on  each  was  copied. 

4.  A  bronze  medal  was  supported  upon  slips  of  wood, 
placed  on  the  copper,  one-eighth  of  an  inch  above  the  plate. 
After  mercurialization,  the  space  the  medal  covered  was  well- 
marked,  and  for  a  considerable  distance  around  the  mercury 
was  unequally  deposited,  giving  a  shaded  border  to  the  image ; 
the  spaces  touched  by  the  [mercury?]  were  thickly  covered  with 
the  vapour.  ' 


464  Mr.  Hunt  on  Thermography, 

5.  The  above  coins  and  medals  were  all  placed  on  the  plate, 
and  it  was  made  too  hot  to  be  handled,  and  allowed  to  cool 
without  their  being  removed ;  impressions  were  made  on  the 
plate  in  the  following  order  of  intensity, — gold,  silver,  bronze, 
copper.  The  mass  of  the  metal  was  found  to  influence  ma- 
terially the  result ;  a  large  piece  of  copper  making  a  better 
image  than  a  small  piece  of  silver.  When  this  plate  was  ex- 
posed to  vapour,  the  results  were  as  before  (3,  4).  On  rub- 
bing off  the  vapour,  it  was  found  that  the  gold  and  silver  had 
made  permanent  impressions  on  the  copper. 

6.  The  above  being  repeated  with  a  still  greater  heat,  the 
image  of  the  copper  coin  was,  as  well  as  the  others,  most 
faithfully  given,  but  the  gold  and  silver  only  made  permanent 
impressions. 

7.  A  silvered  copper  plate  was  now  tried  with  a  moderate 
warmth  (3).  Mercurial  vapour  brought  out  good  images 
of  the  gold  and  copper ;  the  silver  marked,  but  not  well  de- 
fined. 

8.  Having  repeated  the  above  experiments  many  times  with 
the  same  results,  I  was  desirous  of  ascertaining  if  electricity 
had  any  similar  effect;  powerful  discharges  were  passed 
through  and  over  the  plate  and  discs,  and  it  was  subjected  to 
a  long-continued  current  without  any  effect.  The  silver  had 
been  cleaned  off  from  the  plate  (7),  it  was  now  warmed  with 
the  coins  and  medals  upon  it,  and  submitted  to  discharges 
from  a  very  large  Leyden  jar ;  on  exposing  it  to  mercurial 
vapour,  the  impressions  were  very  prettily  brought  out,  and 
strange  to  say,  spectral  images  of  those  which  had  been  re- 
ceived on  the  plate  when  it  was  silvered  (7) ;  thus  proving 
that  the  influence,  whatever  it  may  be,  was  exerted  to  some 
depth  in  the  metal. 

9.  I  placed  upon  a  plate  of  copper,  blue,  red  and  orange- 
coloured  glasses,  pieces  of  crown  and  flint  glass,  mica,  and  a 
square  of  tracing  paper.  These  were  allowed  to  remain  in 
contact  half  an  hour.  The  space  occupied  by  the  red  glass 
was  well  marked,  that  covered  by  the  orange  was  less  di- 
stinct, but  the  blue  glass  left  no  impression ;  the  shapes  of  the 
flint  and  crown  glass  were  well  made  out,  and  a  remarkably 
strong  impression  where  the  crown  glass  rested  on  the  tracing 
paper,  but  the  mica  had  not  made  any  impression. 

10.  The  last  experiment  repeated,  after  the  exposure  to 
mercurial  vapour ;  heat  was  again  applied  to  dissipate  it ;  the 
impression  still  remained. 

11.  The  experiment  repeated,  but  the  vapour  of  iodine 
used  instead  of  that  of  mercury.  The  impressions  of  the 
glasses  appeared  in  the  same  order  as  before,  but  also  a  very 
beautiful  image  of  the  mica  was  developed,  and  the  paper  well 


and  on  the  recent  discovery  of  Moser.  465 

marked  out,  showing  some  relation  to  exist  between  the  sub- 
stances used  and  the  vapours  applied. 

12.  Placed  the  glasses  used  above  (9,  &c.)  with  a  piece  of 
well-smoked  glass  for  half  an  hour,  one-twelfth  of  an  inch  be- 
low a  polished  plate  of  copper.  The  vapour  of  mercury 
brought  out  the  image  of  the  smoked  glass  only. 

.13.  All  these  glasses  were  placed  on  the  copper  and  slightly 
warmed ;  red  and  smoked  glasses  gave  after  vaporization, 
equally  distinct  images,  the  orange  the  next ;  the  others  left  but 
faint  marks  of  their  forms ;  polishing  with  Tripoli  and  putty 
powder  would  not  remove  the  images  of  the  smoked  and  red 
glasses. 

14.  An  etching,  made  upon  a  smoked  etching  ground  on 
glass,  the  copper  and  glass  being  placed  in  contact.  The 
image  of  the  glass  only  could  be  brought  out. 

15.  A  design  cut  out  in  paper  was  pressed  close  to  a  cop- 
per plate  by  a  piece  of  glass,  and  then  exposed  to  a  gentle 
heat  j  the  impression  was  brought  out  by  the  vapour  of  mer- 
cury in  beautiful  distinctness.  On  endeavouring  to  rub  off 
the  vapour,  it  was  found,  that  all  those  parts  which  the  paper 
covered,  amalgamated  with  mercury,  which  was  removed  from 
the  rest  of  the  plates ;  hence  there  resulted  a  perfectly  per- 
manent white  picture  on  a  polished  copper  plate. 

16.  The  coloured  glasses  before  named  (9,  12)  were  placed 
on  a  plate  of  copper  with  a  thick  piece  of  charcoal,  a  copper 
coin,  the  mica  and  the  paper,  and  exposed  to  a  fervent  sun- 
shine. Mercurial  vapour  brought  up  the  images  in  the  fol- 
lowing order:  smoked  glass,  crown  glass,  red  glass,  mica  beau- 
tifully delineated,  orange  glass,  paper,  charcoal,  the  coin,  blue 
glass ;  thus  distinctly  proving  that  the  only  rays  which  had 
any  influence  on  the  metal,  were  the  calorific  rays.  This  ex- 
periment was  repeated  on  different  metals,  and  with  various 
materials,  the  plate  being  exposed  to  steam,  mercury  and 
iodine;  I  invariably  found  that  those  bodies  which  absorbed 
or  permitted  the  permeation  of  the  most  heat  gave  the  best 
images.  The  blue  and  violet  rays  could  not  be  detected  to 
leave  any  evidence  of  action,  and  as  spectra  imprinted  on  pho- 
tographic papers  by  light,  which  had  permeated  these  glasses, 
gave  evidence  of  the  large  quantity  of  the  invisible  rays  which 
passed  them  freely,  we  may  also  consider  those  as  entirely 
without  the  power  of  effecting  any  change  on  compact  simple 
bodies. 

17.  In  a  paper  which  I  published  in  the  Philosophical 
Magazine  for  October  1840,  I  mentioned  some  instances  in 
which  I  had  copied  printed  pages  and  engravings  on  iodized 
paper,  by  mere  contact  and  exposure  to  the  influence  of  the 

Phil.  Mag.  S.  3.  Vol.  21.  No.  140.  Dec.  1842.      2  I 


4>G6  Mr.  Hunt  on  Thermography, 

calorific  rays,  or  to  artificial  heat.  I  then,  speculating  on  the 
probability  of  our  being  enabled  by  some  such  process  as  the 
one  I  then  named,  to  copy  pictures  and  the  like,  proposed  the 
name  of  Thermography,  to  distinguish  it  from  Photography. 

18.  I  now  tried  the  effects  of  a  print  in  close  contact  with  a 
well-polished  copper  plate.  When  exposed  to  mercury,  I 
found  that  the  outline  was  very  faithfully  copied  on  the  metal. 

19.  A  paper  ornament  was  pressed  between  two  plates  of 
glass,  and  warmed ;  the  impression  was  brought  out  with  tole- 
rable distinctness  on  the  under  and  warmest  glass,  but  scarcely 
traceable  on  the  other. 

20.  Rose  leaves  were  faithfully  copied  on  a  piece  of  tin  plate, 
exposed  to  the  full  influence  of  sunshine,  but  a  much  better 
impression  was  obtained  by  a  prolonged  exposure  in  the  dark. 

21.  With  a  view  of  ascertaining  the  distance  at  which  bodies 
might  be  copied,  I  placed  upon  a  plate  of  polished  copper  a 
thick  piece  of  plate  glass,  over  this  a  square  of  metal,  and  se- 
veral other  things,  each  being  larger  than  the  body  beneath. 
These  were  all  covered  by  a  deal  box,  which  was  more  than 
half  an  inch  distant  from  the  plate.  Things  were  left  in  this 
position  for  a  night.  On  exposing  to  the  vapour  of  mercury 
it  was  found  that  each  article  was  copied,  the  bottom  of  the 
deal  box  more  faithfully  than  any  of  the  others,  the  grain  of 
the  wood  being  imaged  on  the  plate. 

22.  Having  found  by  a  series  of  experiments  that  a  black- 
ened paper  made  a  stronger  image  than  a  white  one,  I  very 
anxiously  tried  to  effect  the  copying  of  a  printed  page  or  a 
print.  I  was  partially  successful  on  several  metals,  but  it  was 
not  until  I  used  copper  plates  amalgamated  on  one  surface, 
and  the  mercury  brought  to  a  very  high  polish,  that  I  pro- 
duced any  thing  of  good  promise.  By  carefully  preparing 
the  amalgamated  surface  of  the  copper  I  was  at  length  enabled 
to  copy  from  paper,  line-engravings,  wood-cuts  and  litho- 
graphs, with  surprising  accuracy.  The  first  specimens  pro- 
duced (which  I  have  the  satisfaction  of  now  submitting  to 
your  inspection),  exhibit  a  minuteness  of  detail  and  sharpness 
of  outline  quite  equal  to  the  early  Daguerreotypes  and  the 
photographic  copies  prepared  with  chloride  of  silver*. 

The  following  is  the  process  at  present  adopted  by  me, 
which  I  consider  far  from  perfect,  but  which  affords  us  very 
delicate  images. 

A  well-polished  plate  of  copper  is  rubbed  over  with  the  ni- 
trate of  mercury,  and  then  well  washed  to  remove  any  nitrate 

*  The  first  faithful  copy  of  the  lines  of  a  copper-plate  engraving  was  ob- 
tained  by  Mr.  Cantabrana,  who  has  since  succeeded  in  procuring  some  to- 
lerable specimens  on  unamalgamated  copper,  which  cannot  be  rubbed  off. 


and  on  the  recent  discovery  of  Moser.  467 

of  copper  which  may  be  formed ;  when  quite  dry  a  little  mer- 
cury taken  up  on  soft  leather  or  linen  is  well  rubbed  over  it, 
and  the  surface  worked  to  a  perfect  mirror. 

The  sheet  to  be  copied  is  placed  smoothly  over  the  mercu- 
rial surface,  and  a  sheet  or  two  of  soft,  clean  paper  being 
placed  upon  it,  it  is  pressed  into  equal  contact  with  the  metal 
by  a  piece  of  glass,  or  flat  board  ;  in  this  state  it  is  allowed  to 
remain  for  an  hour  or  two.  The  time  may  be  considerably 
shortened  by  applying  a  very  gentle  heat  for  a  few  minutes  to 
the  under  surface  of  the  plate.  The  heat  must  on  no  account 
be  so  great  as  to  volatilize  the  mercury.  The  next  process 
is  to  place  the  plate  of  metal  in  a  closed  box,  prepared  for 
generating  the  vapour  of  mercury.  The  vapour  is  to  be  slow- 
ly evolved,  and  in  a  few  seconds  the  picture  will  begin  to  ap- 
pear ;  the  vapour  of  mercury  attacks  those  parts  which  corre- 
spond to  the  white  parts  of  the  printed  page  or  engraving,  and 
gives  a  very  faithful,  but  a  somewhat  indistinct  image.  The 
plate  is  now  removed  from  the  mercurial  box,  and  placed  into 
one  containing  iodine,  to  the  vapour  of  which  it  is  exposed  for 
a  short  time;  it  will  soon  be  very  evident  that  the  iodine  va- 
pour attacks  those  parts  which  are  free  from  mercurial  vapour, 
blackening  them.  Hence  there  results  a  perfectly  black  pic- 
ture, contrasted  with  the  gray  ground  formed  by  the  mercu- 
rial vapour.  The  picture  being  formed  by  the  vapours  of 
mercury  and  iodine,  is  of  course  in  the  same  state  as  a  Da- 
guerreotype picture,  and  is  readily  destroyed  by  rubbing. 
From  the  depth  to  which  I  find  the  impression  made  into  the 
metal,  I  confidently  hope  to  be  enabled  to  give  to  these  sin- 
gular and  beautiful  productions  a  considerable  degree  of  per- 
manence, so  that  they  may  be  used  by  engravers  for  working  on. 

It  is  a  curious  fact  that  the  vapours  of  mercury  and  of  io- 
dine attack  the  plate  differently,  and  I  believe  it  will  be  found 
that  vapours  have  some  distinct  relation  to  the  chemical  or 
thermo-electrical  state  of  the  bodies  upon  which  they  are  re- 
ceived. Moser  has  observed  this,  and  attributes  the  pheno- 
mena to  the  colours  of  the  rays,  which  he  supposes  to  become 
latent  in  the  vapour  on  its  passing  from  the  solid  into  the  more 
subtile  form.  I  do  not  however  think  this  explanation  will 
agree  with  the  results  of  experiments.  I  feel  convinced  that 
we  have  to  deal  with  some  thermic  influence,  and  that  it  will 
eventually  be  found  that  some  purely  calorific  excitement 
produces  a  molecular  change,  or  that  a  thermo-electric  action 
is  induced,  which  effects  some  change  in  the  polarities  of  the 
ultimate  atoms  of  the  solid. 

These  are  matters  which  can  only  be  decided  by  a  series  of 
well-conducted  experiments,  and,  although  the  subject  will 

2  12 


468  Mr.  Hopkins  on  the  Elevation  and 

not  be  laid  aside  by  me,  I  hope  the  few  curious  and  certainly 
important  facts  which  I  have  brought  before  you,  will  elicit 
the  attention  of  those  whose  leisure  and  well-known  experi- 
mental talents  qualify  them  in  the  highest  degree  for  the  in- 
teresting research  into  the  action  of  those  secret  agents  which 
exert  so  powerful  an  influence  over  the  laws  of  the  material 
creation.  Although  attention  was  called  to  the  singular  man- 
ner in  which  vapours  disposed  themselves  on  plates  of  glass 
and  copper,  two  years  since  by  Dr.  Draper,  Professor  of  Che- 
mistry at  New  York,  and  about  the  same  time  to  the  calorific 
powers  of  the  solar  spectrum,  by  Sir  John  Herschel*,  and  to 
the  influence  of  heat  artificially  applied,  by  myself  (17),  yet  it 
is  certainly  due  to  M.  Moser  of  Konigsberg,  to  acknowledge 
him  to  be  the  first  who  has  forcibly  called  the  attention  of 
the  scientific  wrorld  to  an  inquiry  which  promises  to  be  as 
important  in  its  results  as  the  discovery  of  the  electric  pile 
by  Volta. 

As  to  the  practical  utility  of  this  discovery,  when  we  re- 
flect on  the  astonishing  progress  made  in  the  art  of  photo- 
graphy since  Mr.  Fox  Talbot  published  his  first  process,  what 
may  we  not  expect  from  thermography,  the  first  rude  speci- 
mens of  which  exhibit  far  greater  perfection  than  the  early 
efforts  of  the  sister  art  ? 

As  a  subject  of  pure  scientific  interest  thermography  pro- 
mises to  develope  some  of  those  secret  influences  which  ope- 
rate in  the  mysterious  arrangements  of  the  atomic  constituents 
of  matter,  to  show  us  the  road  into  the  yet  hidden  recesses  of 
nature's  works,  and  enable  us  to  pierce  the  mists  which  at 
present  envelope  some  of  the  most  striking  phaenomena,  which 
the  penetration  and  industry  of  a  few  "  chosen  minds"  have 
brought  before  our  obscured  visions.  It  has  placed  us  at  the 
entrance  of  a  great  river  flowing  into  a  mighty  sea,  which 
mirrors  in  its  glowing  waters  some  of  the  most  brilliant  stars 
which  beam  through  the  atmosphere  of  truth. 

Falmouth,  Nov.  7, 1842.  Robert  Hunt. 

LXXXII.  On  the  Elevation  and  Denudation  of  the  District 
of  the  Lakes  of  Cumberland  and  Westmoreland.  By  Wil- 
liam Hopkins,  Esq.,  F.G.S.-f 

THE  general  structure  of  this  district  has  been  long  known  to 
geologists  through  the  labours  of  Professor  Sedgwick  and  other 
geologists.     The  object  of  this  paper  is  to  afford  theoretical  expla- 

*  Philosophical  Transactions,  Part  I.  for  1840,  page  50. 
t  From  the  Proceedings  of  the  Geological  Society,  vol.  iii.  part  ii.  p.  757; 
having  been  read  on  June  1st,  1842. 


Denudation  of  the  Lake  District.  469 

nations  of  the  observed  phenomena  of  elevation  and  denudation. 
The  general  boundary  of  tract  may  be  considered  as  sufficiently 
defined  on  the  north  by  the  band  of  mountain  limestone  which  runs 
from  Kirkby  Stephen  by  Heskel,  on  the  west  by  the  coast,  and  on 
the  south  by  the  discontinuous  and  irregular  band  of  limestone, 
which  again  nearly  meets  the  great  mountain  limestone  ridge  of 
Yorkshire,  by  whfch,  and  the  great  fault  along  its  base,  the  district 
is  bounded  on  the  east.  The  general  strike  of  the  limestone  beds 
at  any  point,  as  well  as  that  of  the  new  red  sandstone  reposing  upon 
them,  coincides  with  the  direction  of  the  boundary  at  that  point, 
except  on  the  east,  where  the  boundary  is  the  great  fault  just  men- 
tioned. Consequently  the  dip  is  nearly  perpendicular  to  the  bound- 
ary, and  round  the  western  side  is  divergent  from  the  extremity  of 
the  axis  of  the  district,  which  may  be  considered  to  extend  from 
near  Scaw  Fell  over  Kirkstone  and  Howgile  Fells.  On  the  west 
the  dip  frequently  amounts  to  between  20°  and  30° ;  and  it  should 
be  remarked,  that  it  appears  to  be  very  nearly  as  great  in  the  new 
red  sandstone  beds  as  in  those  of  the  subjacent  limestone.  The 
mountain  limestone  reposes  unconformably  on  the  older  formations 
which,  within  the  limestone  band,  occupy  the  surface.  The  gene- 
ral strike  appears  to  be  somewhat  north  of  N.E.  and  south  of  S.  W. 
The  surface  of  junction  of  the  mountain  limestone  and  the  older 
formations  beneath  can  be  well  examined  in  many  places,  and  the 
author  concludes  that  the  surface  on  which  the  limestone  was  de- 
posited must  have  been  an  even  surface  in  the  same  sense  in  which 
the  expression  may  be  now  applied,  for  instance,  to  the  bottom  of 
the  German  Ocean.  He  also  concludes  that  this  surface  must  have 
been  horizontal.  This  will  necessarily  follow  from  the  previous  in- 
ference, unless  it  be  contended  that  those  animals  whose  remains 
are  now  found  in  the  lower  limestone  beds  could  exist  in  the  per- 
fect performance  of  all  the  functions  of  life,  at  the  depth  of  several 
thousands  of  feet,  under  an  enormous  pressure  and  in  darkness,  as 
well  as  at  small  depths,  under  small  pressure  and  in  the  light  of  the 
sun. 

This  surface  of  junction  wraps  round  the  outer  portion  of  the 
district,  and,  if  continued  as  an  imaginary  surface,  over  the  central 
portion  in  the  manner  which  the  inclination  of  the  existing  portion 
would  obviously  suggest,  it  would  pass  considerably  over  the  tops 
of  the  highest  mountains  of  the  district,  to  which  it  would  form  a 
complete  envelope.  Hence  it  follows  that  if  the  movement  which 
produced  the  geological  elevation  of  the  existing  portion  of  the  sur- 
face of  junction  affected  the  central  portion  of  the  district  in  the 
same  manner  as  in  all  analogous  cases  in  which  the  evidence  is 
complete,  it  will  follow  that  the  present  surface  of  the  Cumbrian 
mountains  must  have  been  beneath  the  surface  of  the  ocean  at  the 
commencement  of  the  deposition  of  the  mountain  limestone.  The 
truth  of  this  conclusion  involves  that  also  of  the  original  horizon- 
tality  of  the  surface  of  junction. 

The  stratification  of  the  older  rocks  of  the  district  can  afford  no 


470  Mr.  Hopkins  on  the  Elevation  and 

direct  evidence  on  this  point  on  account  of  the  previous  disturbance 
to  which  they  had  been  subjected  ;  but  the  great  faults  of  the  di- 
strict prove  to  demonstration  that  its  central  portion  must  have 
been  submerged  in  the  ocean  subsequently  to  the  formation  of  those 
faults ;  for,  if  an  enormous  denudation  had  not  taken  place  after 
their  formation,  every  large  fault  must  have  given  rise  to  a  mural 
precipice,  or  great  ridge  (such  as  that  which  the  Penrin  and  Craven 
faults  have  produced),  by  the  elevation  of  the  mass  on  one  side  of 
the  fault  relatively  to  that  on  the  other.  The  total  absence  of  any 
such  precipice  or  ridge  where  enormous  faults  unquestionably  exist, 
prove  incontrovertibly  the  submergence  above  asserted. 

Faults. — The  faults  of  this  district  may  be  arranged  in  three 
classes,  according  to  the  evidence  we  possess  of  their  existence : — 

(1.)  Those  which  offer  conclusive  evidence  of  dislocation.  Such 
are  those  of  the  Dudden,  Coniston  Water,  one  between  Coniston 
Water  and  Windermere,  Trentbeck  and  Kentmere. 

(2.)  Faults  along  the  Lake  valleys.  The  existence  of  these  faults 
is  inferred  from  that  of  the  Jakes,  the  formation  of  which  it  would 
appear  impossible  to  account  for  without  referring  them  to  disloca- 
tions along  the  valleys  in  which  they  are  found.  The  bottom  of 
Wastwater,  for  instance,  is  probably  at  a  considerably  lower  level 
than  the  surface  of  the  sea,  and  it  has  not  been  formed  by  the 
filling  up  of  the  lower  end  of  the  valley,  for  the  bottom  of  it  con- 
sists of  the  solid  rock  in  situ.  It  appears  inconceivable  that  such  a 
lake  should  have  been  scooped  out  by  the  action  of  water. 

(3.)  Faults  along  the  upper  portions  of  other  valleys.  If  the 
Lake  valleys  have  originated  in  dislocations  we  seem  justified  in 
inferring,  from  analogy,  that  other  valleys  differing  from  the  former 
only  in  the  circumstance  of  not  containing  lakes,  have  had  a  similar 
origin.  It  should  be  remarked,  however,  that  this  evidence  can 
probably  be  depended  upon  only  in  the  upper  parts  of  the  valleys, 
where  denuding  agencies  must  probably  have  acted  for  a  much 
shorter  period  than  at  lower  levels,  where  they  may  have  formed 
valleys  much  more  independently  of  previous  dislocation. 

Theory  of  Elevation. — If  we  allow  the  conclusiveness  of  the  above 
evidence  of  faults,  we  have  here  a  system  of  which  the  law  is 
obvious.  Round  the  western  extremity  of  the  district  they  diverge 
from  its  highest  point  and  extremity  of  its  axis  of  elevation.  On 
the  north  side  they  assume  northerly,  and  then  north-easterly,  di- 
rections ;  and  on  the  southern  side  they  take  southerly  directions. 
If  we  conceive  a  stratum  of  the  mountain  limestone,  or  the  surface  of 
junction  above  described  to  be  continued  over  the  central  portion 
of  the  district,  its  dip  along  the  faults  would  very  nearly  coincide 
with  their  directions. 

This  is  one  of  the  laws  connecting  the  directions  of  dip  and  of  dis- 
location, resulting  from  the  theory  which  the  author  has  elsewhere 
developed,  supposing  the  faults  to  have  been  caused  by  the  elevation 
which  gave  to  the  limestone  beds  their  present  position.  This  theory 
would  therefore  appear  to  assign  these  faults  to  the  epoch  of  the 


Denudation  of  the  Lake  District.  471 

disturbance  of  the  carboniferous  system.  There  is  also,  however, 
another  law  pointed  out  by  that  theory,  viz.  that  a  system  of  dislo- 
cations may  also  exist  having  the  same  directions  as  the  strike  of 
the  disturbed  beds.  Consequently  those  faults  which  are  in  the 
direction  of  the  strike  of  the  beds  of  the  older  formations,  may, 
according  to  this  theory,  be  assigned  to  the  epoch  of  the  elevation 
and  dislocation  of  those  beds.  The  great  faults  of  the  Dudden, 
Coniston  Water,  and  Troutbeck  are  of  this  class,  since  their  direc- 
tions coincide  very  nearly  with  the  mean  strike  of  the  older  beds. 
Theory,  therefore,  leaves  the  epoch  of  these  faults  undetermined ; 
nor  has  the  point  been  settled  by  observation,  since  there  is  no 
direct  evidence  to  prove  whether  these  faults  have  affected  the 
mountain  limestone  or  not. 

It  may  be  thought  that  the  mountain  limestone  must  have  been 
more  decidedly  disturbed  by  the  great  faults  above  mentioned  had 
they  been  produced  at  the  epoch  of  the  disturbance  of  the  carboni- 
ferous system.  It  must  be  remarked,  however,  that  the  direct  evi- 
dence of  these  faults  is  found  only  at  a  considerable  distance  from  the 
existing  portions  of  mountain  limestone,  and  that  if  they  originated  in 
that  central  and  local  elevation  to  which  the  actual  configuration  of 
this  tract  must  be  due  (at  whatever  epoch  it  took  place),  the  diver- 
ging faults,  however  great  near  the  centre  of  the  district,  would  dis- 
appear as  they  approached  its  boundary.  The  author,  however,  is 
disposed  to  refer  the  four  great  faults  above  mentioned  to  the 
disturbance  of  the  older  rocks.  They  appear  to  have  produced 
such  enormous,  relative  displacements  of  the  masses  on  opposite 
sides  of  them,  as  may  be  more  probably  referrible  to  the  more  in- 
tense action  of  the  elevatory  forces  which  disturbed  the  older 
formations  than  to  that  which  subsequently  took  up  the  mountain 
limestone. 

But,  it  may  be  urged,  the  directions  of  these  great  dislocations 
do  not  coincide  with  that  of  the  actual  strike  of  the  older  beds.  The 
author  shows  that  if  this  coincidence  existed  (as  it  ought  according 
to  theory)  after  the  elevation  of  the  older  beds,  but  previously  to 
that  of  the  limestone,  it  could  not  possibly  exist  after  the  latter  ele- 
vation in  those  parts  in  which  the  deviation  from  such  coincidence 
is  now  recognised,  viz.  along  the  band  of  limestone  interstratified 
with  the  older  beds,  and  crossing  the  above  faults  in  its  course 
from  the  Dudden  to  Troutbeck.  To  one  who  has  a  distinct  con- 
ception of  the  geometry  of  the  subject,  it  will  easily  appear  that  the 
elevation  which  gave  its  present  position  to  the  beds  of  mountain 
limestone,  and  (as  the-author  conceives)  its  dome-like  configuration 
to  the  district,  would  necessarily  give  to  the  strike  of  the  beds 
along  the  above  line,  a  direction  approximating  more  to  east  and 
west  than  the  original  strike,  while  it  would  have  no  effect  on  the 
direction  of  a  vertical  fault  as  determined  by  its  intersection  with 
the  surface.  This  accounts  for  the  actual  difference  between  the 
directions  of  the  above  faults  and  that  of  the  strike. 

Upon  the  whole,  the  author  considers  it  probable  that  the  four 


472  Mr.  Hopkins  on  the  Elevation  and 

great  parallel  faults  above  mentioned  are  due  to  the  elevation  of 
the  older  rocks,  the  fractures  having  been  probably  renewed  by  the 
elevation  of  the  carboniferous  series.  The  divergent  faults  he  con- 
ceives to  be  unquestionably  due  to  the  movement  which  impressed 
upon  the  district  its  peculiar  configuration,  and  the  geological  ele- 
vation to  which  that  configuration  is  due,  whatever  be  the  epoch  to 
which  that  movement  may  be  referred.  If  this  be  the  case,  these 
faults  are  entirely  in  accordance  with  theory. 

It  appears  to  the  author  that  this  movement  commenced  with 
the  breaking  up  of  the  carboniferous  series,  and  was  continued,  or 
rather  perhaps  resumed,  after  the  deposition  of  the  new  red  sand- 
stone. If  the  beds  of  these  formations  were  originally  horizontal, 
as  above  contended,  this  conclusion  must  necessarily  be  true,  as 
shown  by  the  present  inclination  of  these  beds.  Whether  the  lime- 
stone beds  were  strictly  sedimentary,  or  formed  in  the  manner  of 
coral  reefs,  the  author  contends  equally  for  the  original  horizon- 
tality  of  the  surfaces  of  stratification  ;  and  that  such  was  the  ori- 
ginal character  of  the  beds  of  new  red  sandstone,  no  geologist,  he 
conceives,  can  doubt  for  a  moment.  If  this  be  allowed,  the  above 
conclusion  respecting  the  epoch  of  elevation  appears  as  incontro- 
vertible as  the  nature  of  geological  evidence  will  admit  of. 

Series  of  Geological  Events. — After  the  elevation  of  the  older  rocks, 
including  the  old  red  sandstone,  the  whole  district  must  have  been 
under  the  surface  of  the  sea,  and  subjected  to  the  powerful  action 
of  denuding  causes,  by  which  the  upturned  edges  of  the  disturbed 
beds  were  worn  to  an  even  surface,  and  the  existing  masses  of  old 
red  conglomerate  washed  into  the  hollows. 

The  mountain  limestone  was  deposited  on  the  worn  and  even 
surface  of  the  older  rocks,  and,  if  the  conditions  were  sufficiently 
favourable  for  its  formation,  may  have  extended  over  the  whole 
district. 

The  great  movement  which  broke  up  the  carboniferous  series 
gave,  in  part,  its  dome-like  form  to  the  district,  and  elevated  its  sur- 
face very  nearly  to,  or  perhaps  above,  the  surface  of  the  ocean. 

The  deposition  of  the  new  red  sandstone  afterwards  took  place, 
but  did  not  probably  extend  over  the  district  on  account  of  the  ele- 
vation already  given  to  it.  This  formation  probably  thinned  off  as 
it  approached  the  central  elevation,  but  was  deposited  in  much 
greater  thickness  than  it  has  at  present  in  the  Vale  of  Eden.  From 
the  present  height  and  thickness  of  the  sandstone  near  Penrith,  the 
author  thinks  it  probable  that  the  depth  of  the  submarine  valley 
immediately  west  of  Stainmoor  was  not  more  than  300  or  400  feet, 
and  perhaps  considerably  less,  measuring  from  the  level  of  the 
lowest  part  of  the  Stainmoor  pass. 

To  this  period  of  repose  succeeded  another  of  disturbance,  in 
which  the  new  red  sand  was  dislocated  and  elevated.  It  was  during 
this  period,  the  author  conceives,  that  the  surface  of  the  district 
first  began  to  acquire  any  permanent  and  considerable  elevation 
above  the  surface  of  the  sea.     The  denudation  of  the  red  sand 


Denudation  of  the  Lake  District.  473 

would  commence  with  these  movements,  but  was  probably  com- 
pleted only  as  the  whole  tract  of  country  emerged  slowly  from  be- 
neath the  surface  of  the  sea.  If  we  reject  the  glacial  theory  in  its 
application  to  the  transport  of  blocks,  as  totally  inadmissible  in  the 
case  before  us,  this  emergence  must  necessarily  have  taken  place 
subsequently  to  the  transport  of  blocks  from  the  Cumbrian  moun- 
tains across  Stainmoor. 

The  author  conceives  the  valleys  of  the  district  to  have  been 
formed  during  this  gradual  emergence  ;  the  action  of  denuding 
causes  being  facilitated  by  previous  dislocations,  the  masses,  the 
removal  of  which  formed  the  valleys,  would  at  the  same  time  be 
transported  and  spread  over  the  surrounding  country.  The  forma- 
tion of  the  existing  lakes  must  have  been  one  of  the  most  recent 
events  in  the  geological  history  of  this  region. 

Period  of  Transport  of  Erratic  Blocks.— The  author  thinks  that 
geologists  have  frequently  limited  too  much  the  period  during 
which  the  transport  of  blocks  may  have  taken  place.  When  blocks 
are  found  reposing  on  an  undisturbed  formation,  the  only  con- 
clusive inference  which  can  be  drawn  from  the  fact  is,  that  the  last 
stage  of  their  movement  was  posterior  to  the  deposition  of  the  beds 
on  which  they  rest.  If  the  beds  be  much  disturbed,  but  all  the 
irregularities  and  asperities  of  its  external  surfaces  worn  away  by 
long-continued  attrition,  we  may  generally  conclude  that  the  same 
action  would  have  worn  away  any  blocks  previously  existing  on 
its  surface,  and  therefore  any  blocks  now  existing  on  such  surface 
must  have  been  lodged  there  subsequently  to  its  denudation.  Also, 
when  diluvial  gravel  contains  organic  remains,  we  may  conclude 
that  the  last  stage  of  its  movement  must  have  been  subsequent  to 
the  existence  of  the  animals  whose  remains  are  entombed  in  it.  To 
contend,  for  instance,  that  the  diluvial  gravel  of  Norfolk  was  not  re- 
moved from  its  original  site  till  the  post-tertiary  period,  is  to  draw 
an  inference  which  the  author  deems  altogether  inadmissible. 

The  great  mass  of  diluvium  from  the  Cumbrian  mountains  re- 
poses on  nothing  more  recent  than  the  new  red  sandstone,  and  the 
author  conceives  that  its  transport  might  begin  with  the  elevatory 
movements  which  disturbed  that  formation,  when  the  surface  of  the 
present  mountainous  district  began  to  rise  permanently  above  the 
surface  of  the  ocean,  and  the  valleys  began  to  be  formed.  This  is 
the  more  remote  limit  of  the  period  to  which  the  transport  of 
diluvium  and  blocks  can  be  referred  ;  the  other  limit  is  the  emer- 
gence of  Stainmoor  (over  which  so  many  blocks  passed)  from  be- 
neath the  surface  of  the  ocean,  assuming  the  total  inadequacy  of 
the  glacial  theory  to  account  for  that  transport.  The  present 
height  of  Stainmoor  is  stated  to  be  about  1500  feet  above  the  sea; 
consequently  an  elevation  of  from  1500  to  2000  feet  must  have 
taken  place  in  these  regions  since  the  transport  of  the  Cumbrian 
blocks  across  the  Penim  ridge — a  fact  which  appears  corroborative 
of  the  author's  opinion,  that  the  district  had  scarcely  emerged  from 
the  ocean  at  the  more  remote  of  the  above-mentioned  limits  of  the 
possible  period  of  transport. 


474  Mr.  Hopkins  on  the  Elevation  and 

Modes  of  Transport — Glacial  Theory. — This  theory,  in  its  appli- 
cation to  the  transport  of  blocks  across  Stainmoor,  involves  such 
obvious  mechanical  absurdities,  that  the  author  considers  it  totally 
unworthy  of  the  attention  of  the  Society.  Polished  and  striated  rocks 
were,  however,  detected  by  Dr.  Buckland,  and  pointed  out  by  him 
to  the  author  in  various  places.  The  author  does  not  feel  himself 
called  upon  to  offer  any  decided  opinion  as  to  the  cause  of  such 
phaenomena ;  he  here  speaks  of  the  glacial  theory  only  with  re- 
ference to  the  solution  it  offers  of  the  problem  of  the  transport  of 
blocks  or  detritus  to  distant  localities. 

Iceberg  Theory. — There  appears  to  be  no  doubt  that  floating  ice 
may  have  played  an  important  part  in  some  cases  in  the  transport 
of  large  blocks,  but  the  author  doubts  whether  such  agency  has  been 
at  all  employed  in  the  case  under  consideration.  In  the  first  place, 
he  cannot  but  consider  it  absurd  to  attribute  the  formation  of  a  bed 
of  diluvium  spread  out  with  approximate  uniformity  over  an  extended 
area  to  the  action  of  floating  ice.  Such  a  distribution  of  the  trans- 
ported matter  is  the  necessary  effect  of  broad  currents  of  water, 
which,  at  most,  is  the  merely  -possible  effect  of  floating  ice.  Se- 
condly, there  appears  no  adequate  reason  why  blocks  transported 
by  floating  ice  should  diminish  in  size  as  their  distance  from  their 
original  site  increases ;  why  the  Cumbrian  blocks  on  the  eastern 
coast  of  Yorkshire  should  be  generally  much  smaller  than  those  less 
remote  from  the  place  whence  they  came.  Thirdly,  the  theory  in 
its  application  to  the  case  before  us  involves  a  great  physical  diffi- 
culty— a  depression  of  temperature,  for  which  no  adequate  cause 
has  yet  been  assigned.  The  author  does  not  admit  the  parallel 
which  has  been  drawn  between  this  case  and  that  of  places  in  equal 
latitudes  in  South  America  or  that  of  the  island  of  Georgia. 

Transport  by  Currents  of  Water. — It  has  already  been  remarked 
that  the  spreading  x>ut  of  diluvial  matter  into  a  horizontal  stratum 
may  be  regarded  as  the  necessary  consequence  of  broad  general 
currents,  and  that  this  has  been  the  agency  by  which  the  mass  of 
diluvium  covering  the  surface  of  Lancashire  has  been  carried  there 
does  not  admit,  in  the  author's  opinion,  of  the  smallest  doubt.  He 
accounts  for  the  existence  of  currents  diverging  from  the  centre  of 
the  district  in  question  by  a  repetition  of  paroxysmal  elevations. 

Suppose  a  certain  area  at  the  bottom  of  an  ocean  to  be  suddenly 
elevated ;  and,  for  the  greater  clearness,  suppose  the  elevated  area 
to  be  a  circle  of  twenty  miles  in  diameter,  its  elevation  to  be  50 
feet,  and  the  depth  of  the  ocean  300  or  400  feet.  If  the  elevation 
were  sufficiently  gradual  no  sensible  wave  would  result  from  it,  but 
if  it  were  sudden  the  surface  of  the  water  above  the  uplifted  area 
would  be  elevated  very  nearly  as  much  as  the  area  itself,  and  a 
diverging  wave  would  be  the  consequence.  Its  front  would  be  steep, 
like  that  of  the  tidal  wave  in  some  rivers  called  the  bore,  so  that  the 
highest  part  or  summit  of  the  wave  would  not  be  far  from  its  front. 
The  height  at  its  summit  would  be  approximately  equal  to  the  ele- 
vation of  the  uplifted  area,  or,  in  the  case  supposed,  nearly  50  feet. 
The  velocity  with  which  the  front  would  diverge  would  depend  on 


Denudation  of  the  Lake  District.  475 

the  height  of  the  wave  and  the  depth  of  the  ocean.  In  a  certain  time 
the  water  first  raised  above  the  general  level  of  the  ocean  imme- 
diately over  the  elevated  area  would  run  off,  leaving  the  surface  of 
the  ocean  there  at  its  original  level ;  and  when  this  should  be  com- 
pleted the  posterior  boundary  of  kthe  wave  would  be  immediately 
over  the  periphery  of  the  elevated  area.  During  the  same  time  the 
front  of  the  wave  would  move  on  through  a  certain  space,  still  form- 
ing a  circle  of  which  the  centre  would  be  immediately  over  that  of 
the  elevated  area.  Thus  the  whole  wave  would  at  the  instant  now 
referred  to  be  comprised  between  two  concentric  circles,  the 
distance  between  which  would  be  the  breadth  of  the  wave.  After- 
wards, as  the  front  or  anterior  boundary  of  the  wave  spread  out- 
wards, so  would  the  posterior  boundary  move  forward  in  a  similar 
manner,  always  preserving  the  annular  form  just  mentioned.  As 
the  wave  diverged  its  height  would  gradually  diminish  till  it  be- 
came finally  insensible. 

The  motion  of  the  wave  here  spoken  of  is  altogether  distinct 
from  the  motion  of  translation  of  the  aqueous  particles.  This 
latter  motion,  however,  accompanies  the  former  in  the  kind  of  wave 
here  described,  producing  a  current  like  that  of  a  tidal  river  oppo- 
site to  the  usual  course  of  the  stream.  Each  particle  begins  to 
move  onward  the  instant  when  the  anterior  boundary  of  the  wave 
has  reached  it,  but  its  motion  being  always  slower  than  that  of  the 
wave,  it  will  afterwards  be  overtaken  by  the  posterior  boundary  of 
the  wave,  which  will  then  leave  the  fluid  particle  behind  and  at 
rest.  Thus,  at  any  proposed  point,  the  current  will  begin  when  the 
front  of  the  wave  reaches  that  point,  will  increase  there  till  the 
highest  part  of  the  wave  is  directly  over  it,  and  will  then  gradually 
decrease  till  the  posterior  boundary  of  the  wave  has  reached  the 
point  in  question,  where  the  current  will  then  cease  altogether. 
There  will  be  no  reflexion  of  this  great  solitary  wave  unless  it  meet 
with  some  obstruction  in  the  course  of  its  motion. 

We  are  indebted  to  Mr.  Russel  for  our  knowledge  of  the  pro- 
perties of  these  great  waves  of  translation.  He  has  further  ascer- 
tained, experimentally,  that  the  velocity  of  the  wave  is  equal  to  that 
which  would  be  acquired  in  vacuum  by  a  stone  falling  under  the 
action  of  gravity  through  a  height  equal  to  half  the  depth  of  the 
ocean  measured  from  the  crest  of  the  wave.  He  has  also  found 
that  the  velocity  of  the  current  at  any  point  is  independent  of  the 
depth  of  that  point,  being  the  same  at  the  bottom  as  at  the  surface*. 
From  these  data  it  is  easy  to  calculate  the  velocity  of  the  current 
which  attends  the  wave,  when  the  depth  of  the  ocean  and  original 
height  of  the  wave  are  known.  And  hence  it  appears  that  there  is 
no  difficulty  in  accounting  for  a  current  of  twenty-five  or  thirty 

*  Mr.  Russel's  experiments  were  made  with  much  smaller  waves  and  at 
much  smaller  depths  than  those  above  spoken  of ;  but  he  expresses  a  con- 
viction (and,  as  the  author  conceives,  a  well-founded  conviction)  that  the 
same  results  will  hold  for  much  greater  depths  than  those  experimented 
with. 


476  Mr.  Hopkins  on  the  Lake  District. 

miles  an  hour,  if  we  allow  of  paroxysmal  elevations*  of  from  100 
to  200  feet.  This  velocity  will  decrease  as  the  wave  expands, 
unless  the  current  be  constrained  to  pass  through  a  comparatively 
narrow  channel,  like  that  which  must  have  been  formed  by  the  pass 
Stainmoor  when  just  submerged  beneath  the  surface  of  the  ocean. 
In  such  case  the  velocity  of  the  current  might  be  much  increased. 

With  respect  to  the  magnitude  of  the  blocks  which  might  be 
moved  by  a  current  of  given  velocity,  the  author  remarks,  that  the 
facility  with  which  the  transport  of  a  block  may  be  effected 
depends  principally  on  its  form.  The  more  it  approximates  to  per- 
fect sphericity,  the  less,  cceteris  paribus,  will  be  the  force  necessary 
to  remove  it.  The  author  conceives  that  there  is  no  doubt  what- 
ever but  that  blocks,  not  more  spherical  than  many  rolled  blocks  are 
observed  to  be,  of  five  tons  weight  and  upwards,  might  be  moved 
under  favourable  circumstances,  by  a  current  of  ten  miles  an  hour. 
That  the  force  of  a  current  increases  in  the  ratio  of  the  square  of 
its  velocity  has  been  distinctly  established  by  experiment  for  all 
velocities  up  to  eleven  or  twelve  miles  an  hour ;  nor  does  there 
appear  to  be  any  reason  for  doubting  that  the  same  law  holds  for 
much  greater  velocities.  Assuming  this  law,  the  author  states  it 
as  the  result  of  a  simple  calculation,  that  if  a  certain  current  be 
just  able  to  move  a  block  of  given  weight  and  form,  another  cur- 
rent of  double  the  velocity  of  the  former  would  move  a  block  of  a 
similar  form,  whose  weight  should  be  that  of  the  former  in  the 
ratio  of  26  :  1,  i.e.  of  64  to  1.  If  the  velocity  of  the  second  cur- 
rent were  treble  that  of  the  first,  the  weights  of  the  two  similar 
blocks  would  be  in  the  ratio  36  :  1,  i.  e.  of  729  to  1,  and  so  on  for 
other  velocities.  Hence,  if  a  current  of  ten  miles  an  hour  would 
move  a  block  of  five  tons,  a  current  of  twenty  miles  an  hour  might, 
under  similar  circumstances,  move  one  of  320  tons.  No  transported 
blocks  approximating  to  this  weight  appear  to  have  been  moved 
from  the  Cumbrian  mountains.  The  author,  therefore,  does  not 
hesitate  to  affirm  the  entire  adequacy  of  the  cause  now  explained 
to  transport  all  the  erratic  blocks  which  have  been  identified  as  be- 
inf  derived  from  that  region,  nor  can  he  therefore  hesitate  to  con- 
clude that  such  has  been  the  agency  by  which  that  transport  has 
actually  been  effected. 

It  has  been  urged  that  no  current  could  carry  boulders  up  the 
escarpment  of  the  Eastern  Wolds  of  Yorkshire,  nor  does  the  author 
contend  for  any  such  effect  of  currents.  Whether  the  blocks  now 
found  on  the  wolds  were  transported  there  by  currents  or  by  float- 
ing ice,  the  transport  must  have  taken  place  before  that  region 
emerged  from  the  ocean.  But  the  author  contends  that  the  forma- 
tion of  such  an  escarpment  as  that  referred  to,  or  like  the  oolitic 

*  If  the  extent  of  country  elevated  be  considerable  (like  that  of  the 
district  of  the  Lakes,  for  instance)  the  elevation  might  occupy  several 
minutes  and  still  produce  the  great  wave  above  described.  If  the  elevation 
were  produced  more  slowly,  the  height  of  the  wave,  and  consequently  the 
velocity  of  the  current,  would  be  proportionably  less. 


Proceedings  of  Learned  Societies.  477 

escarpment  which  overlooks  the  valley  of  the  Severn,  could  not 
possibly  be  formed  by  oceanic  currents,  except  under  very  peculiar 
conditions,  which  we  have  no  reason  to  believe  to  have  existed  in 
those  localities.  On  the  contrary,  the  formation  of  such  escarp- 
ments during  the  gradual  emergence  of  the  land  would  be  a  neces- 
sary consequence  of  that  emergence  under  conditions  which  must 
have  obtained  in  numerous  instances.  Hence  the  author  concludes 
that  the  escarpment  of  the  wolds  was  formed  subsequently  to  the 
transport  of  the  blocks  which  are  now  found  in  that  region.  He 
conceives  that,  with  respect  to  the  theory  of  transport  by  currents, 
difficulties  founded  on  existing  inequalities  of  surface  have  been  far 
too  strongly  contended  for  on  the  one  hand,  and  too  easily  admitted 
on  the  other. 

The  author  is  anxious  that  his  views  should  not  be  misunder- 
stood as  respects  the  glacial  theory,  or  that  which  would  refer  the 
transport  of  blocks  to  floating  ice.  He  is  quite  prepared  to  believe 
in  the  possible  extension  of  glaciers  beyond  the  boundaries  to 
which  they  now  extend,  wherever  such  greater  extension  can  be  ac- 
counted for  consistently  with  the  conclusions  of  collateral  branches 
of  physical  science ;  and  also  to  believe  that  such  more  extensive 
glaciers,  where  they  have  existed,  may  have  been  the  means  of 
transport  of  erratic  blocks,  provided  sufficient  mechanical  cause 
can  be  assigned  for  their  movement.  With  respect  to  the  iceberg 
theory,  though  he  rejects  its  application  to  the  case  investigated  in 
this  communication  as  altogether  unnecessary  to  account  for  the 
observed  phaenomena,  he  conceives  that  floating  ice  may  probably 
have  been  the  most  efficient  agent  in  transporting  the  larger  blocks 
of  colder  regions  from  their  original  localities. 


LXXXIII.     Proceedings  of  Learned  Societies. 

ROYAL  ASTRONOMICAL  SOCIETY. 
[Continued  from  p.  401.] 
March  1 1 ,  f  ■  THE  following  communications  were  read : — 

1842.  JL  1.  On  an  Instrument  adapted  for  observing  Right 
Ascensions  and  Declinations  of  Stars  independently  of  time,  accom- 
panied by  Drawings  made  with  the  Camera  Lucida  by  Captain  Basil 
Hall,  R.N.  By  M.  Wettinger.  Communicated,  with  a  Letter  of  De- 
scription, to  Sir  J.  F.  W.  Herschel,  Bart.,  by  Capt.  Basil  Hall,  R.N. 

The  instrument  contrived  by  M.  Wettinger  is  so  fully  described 
in  Captain  Hall's  letter,  that  an  independent  abstract  of  M.  Wettin- 
ger's  paper  is  unnecessary.  The-  following  is  a  copy  of  the  letter, 
dated  Malta,  Dec.  6,  1841  :— 

"  My  dear  Sir  John, — I  have  had  my  attention  lately  called  to 
an  invention  which  appears  to  me  so  ingenious,  and  grounded  upon 
such  good  principles,  that  I  think  a  description  of  it  may  interest 
you,  and  perhaps  be  considered  by  you  as  worthy  of  being  brought 
to  the  notice  of  the  Astronomical  Society.     Of  this,  however,  you 


478  Royal  Astronomical  Society, 

are  the  best  judge ;  and  I  shall  therefore  merely  give  you  the  means 
of  examining  the  pretensions  of  the  instrument.  In  this  view  I  have 
made  three  sketches  of  the  model  with  the  camera  lucida,  and  I  have 
added  to  each  the  same  letters  of  reference  to  the  same  parts.  I 
transmit  to  you  also  the  opinion  of  Carlini  of  Milan,  and  of  his  col- 
leagues, as  to  this  instrument,  which  was  submitted  to  their  ex- 
amination some  time  ago. 

"  I  may  begin  by  stating  that  the  chief  object  of  the  instrument 
is  to  determine  the  difference  of  right  ascension  between  any  two 
stars,  without  the  agency  of  time  as  an  element,  the  equatoreal  an- 
gular difference  between  them  being  measured  directly,  in  arc,  on 
an  hour-circle,  graduated  in  degrees  and  minutes  for  that  purpose. 
It  is  true  that  time  does  enter  as  an  element  into  the  principle  of  the 
instrument,  inasmuch  as  a  certain  part  of  the  machinery  is  moved 
by  clock-work,  in  the  manner  used  in  many  equatoreals ;  but  this 
agency  is  purely  mechanical  and  subsidiary,  and  does  not  require 
that  the  absolute  time  should  either  be  exactly  known,  or  its  march 
be  exactly  kept. 

"  The  instrument  is  essentially  an  equatoreal  arc,  in  its  structure, — 
that  is  to  say,  its  principal  axis  is  directed  to  the  pole,  and  it  carries 
a  telescope  capable  of  being  directed  to  any  star  which  is  above  the 
horizon.  [I  should  mention,  in  passing,  that  the  clock-work  ma- 
chinery is  not  included  in  the  model ;  and  there  may  be  observed 
some  other  mechanical  omissions,  it  not  having  been  thought  worth 
while  to  encumber  either  the  model  or  the  description  with  more 
details  than  are  necessary  to  an  explanation  of  the  principle  and 
workings  of  the  instrument.] 

"  The  principal  or  polar  axis  of  the  instrument  is  made  hollow — 
in  fact,  is  a  telescope,  having  at  its  upper  extremity  a  small  reflector 
or  speculum  capable  of  being  directed  at  any  angle  into  the  tube  of 
this  axis  telescope.  The  object-glass  of  this  telescope  is  fixed  not 
at  its  extremity,  but  about  half-way  between  the  upper  end  and  the 
centre.  At  the  centre  there  is  placed  another  reflector,  which  stands 
at  an  angle  of  45°  with  the  length  of  the  tube,  to  receive  the  image 
of  a  star  formed  by  the  object-glass  from  the  rays  reflected  from  the 
upper  speculum.  The  side  of  the  axis  telescope  is  perforated,  in 
order  to  allow  the  image  of  the  star  which  is  reflected  from  the  central 
speculum  to  pass  into  the  middle  of  another  telescope,  which,  for  di- 
stinction, may  be  called  the  declination  telescope,  as  it  is  attached  to, 
and  carries  with  it,  a  declination  circle.  In  the  middle  of  this  de- 
clination telescope  there  is  fitted  a  very  small  reflector,  at  an  angle 
of  45°  to  its  length,  on  which  the  image  of  the  star  reflected  from 
the  central  speculum  is  received  and  transmitted  to  the  eye  of  the 
observer,  in  every  position  of  the  declination  telescope. 

"  The  further  arrangements  of  the  instrument  will  perhaps  be 
more  readily  understood  by  describing  the  manner  of  using  it,  than 
by  giving  a  detailed  explanation  of  the  parts. 

"  In  commencing  an  observation,  the  upper  speculum  is  directed 
to  a  standard  star  of  the  first  or  second  magnitude,  partly  by  moving 
it  on  its  own  axis  of  rotation,  so  as  to  direct  the  rays  into  the  prin- 


Royal  Astronomical  Society.  479 

cipal  axis  telescope,  and  partly  by  the  equate-real  motion,  either  of 
the  whole  apparatus,  or  by  the  rotatory  movement  of  the  principal 
axis,  by  means  of  the  declination  telescope.  This  motion,  I  may 
mention  by  the  way,  of  the  principal  or  polar  axis  may  be  made  at 
pleasure,  independently  of  a  large  frame- work  attached  to  the  in- 
strument, which  is  moved  by  the  clock-work,  There  is  an  hour- 
circle  in  the  plane  of  the  meridian,  fixed  to  this  outer  frame- work, 
and  another  circle  fixed  to  the  lower  extremity  of  the  polar  axis, 
which  may  be  clarfijped  or  freed  from  that  which  belongs  to  the  frame- 
work. The  speculum,  at  the  other  extremity  of  the  axis,  is  so  con- 
trived that  it  moves  along  with  the  frame-work. 

"  It  will  therefore  be  understood,  that  if  the  upper  speculum  be 
so  directed  towards  a  star  that  the  rays  reflected  from  it  pass  down 
the  polar  axis  telescope,  they  will  be  received  and  reflected,  first, 
from  the  central  speculum,  and  secondly,  from  the  speculum  in  the 
declination  telescope,  to  the  eye,  in  whatever  position  the  declina- 
tion telescope  may  be.  Now,  if  the  hour-circles  be  clamped,  so  as 
to  form  one,  and  the  frame-work  be  put  into  gear  with  the  clock- 
work, the  whole  will  move  round  at  the  rate  observed  by  the  heavens, 
and,  consequently,  the  image  of  the  star  reflected  from  the  upper 
speculum  will  continue  in  the  centre  of  the  field  of  the  declination 
telescope,  for  any  required  length  of  time,  and  in  every  possible  po- 
sition of  that  telescope. 

"  Suppose,  now,  that  the  relative  position  of  the  equatoreal  circle, 
fixed  to  the  frame,  and  that  carried  by  the  polar  axis,  be  carefully 
ascertained  by  reading  off  their  graduated  circumferences,  by  micro- 
scopes or  otherwise,  and  that  then  the  circle  carried  by  the  polar 
axis  be  undamped,  that  axis  will  be  left  free  to  revolve  and  to  carry 
with  it  the  declination  circle,  and  Likewise  the  declination  telescope, 
but  without  interfering  with  what  may  be  called  the  celestial  move- 
ment of  the  frame,  or  that  of  the  upper  speculum,  which,  by  going 
along  with,  continues  to  reflect  the  rays  from  the  star  to  which  it 
was  originally  directed ;  and,  consequently,  to  preserve  the  image  of 
that  star  constantly  in  the  centre  of  the  field  of  the  declination  tele- 
scope. This  declination  telescope  is  now  directed  to  any  other  given 
star  whatsoever,  the  image  of  which,  viewed  directly,  is  to  be  brought 
into  coincidence  with  that  seen  by  reflection  from  the  upper  specu- 
lum. If  now  the  equatoreal  circles  be  clamped,  and  a  second  set 
of  readings  be  made,  it  is  obvious  that  the  difference  between  the 
two  will  be  the  difference,  in  arc,  of  the  right  ascensions  of  the 
stars. 

"  When  the  observation  commences,  the  declination  telescope  is 
directed  to  the  standard  star,  as  well  as  the  upper  speculum,  so  that 
the  images,  seen  direct  and  by  reflection,  are  made  to  coincide  in 
the  centre  of  the  field  of  view  of  the  declination  telescope.  The 
graduations  of  the  declination  circle  are  then  read  off,  to  be  com- 
pared with  those  when  the  second  observation  is  made,  or  that  of 
the  star  whose  place  is  to  be  determined.  The  difference  of  these 
readings  will  give  the  difference  of  the  declinations  of  the  two  stars, 
in  the  same  manner  that  the  difference  of  the  readings  of  the  two 


480  Royal  Astronomical  Society. 

concentric  hour-circles  (as  they  may  be  called)  at  the  lower  end  of 
the  polar  axis,  gives  the  difference  of  the  right  ascensions. 

"  If  clock-work  machinery  be  not  in  such  perfect  adjustment  as 
to  keep  the  standard  star,  first  observed,  correctly  in  the  centre  of 
the  field  of  view,  it  may  be  brought  to  that  point  by  a  tangential 
movement  of  the  frame-work,  to  be  made  by  hand,  at  the  moment 
of  making  the  second  observation,  without  in  any  respect  vitiating 
the  integrity  of  the  observation,  for  this  small  movement  does  no 
more  than  compensate  for  any  error  in  the  goingpof  the  clock. 

"  As  it  may  not  be  always  convenient  to  move  the  whole  frame 
which  is  attached  to  the  clock-work,  the  upper  speculum,  at  the 
upper  end  of  the  axis,  is  so  fitted  as  to  be  capable  of  being  turned 
round  independently  of  the  frame,  to  which  it  is  fixed  by  a  mode- 
rately stiff  collar.  This  movement,  which  may  be  made  roughly  by 
hand,  or  more  nicely  by  a  tangent  screw,  enables  the  observer, 
without  stopping  the  clock-work  machinery,  to  direct  the  speculum 
to  any  given  standard  star ;  and  I  may  observe  that  only  those  of 
the  first  and  second  magnitudes  are  named  for  this  purpose  by  M. 
Wettinger,  as  he  fears  the  light  lost  by  the  three  successive  reflec- 
tions might. render  any  less  brilliant  stars  invisible.  This,  however, 
does  not  affect  stars  viewed  through  the  declination  telescope,  which 
looks  directly  to  its  object,  and  is  supposed  to  be  capable  of  seeing 
small  stars  as  readily  as  large  ones. 

"  Observations  for  determining  the  differences  of  right  ascension 
and  declination,  in  arc,  between  a  standard  star  and  any  other,  both 
being  above  the  horizon,  may  be  repeated  as  often  as  required ; 
and  it  does  not  appear  how,  supposing  the  machinery  perfect,  any 
error  can  enter  into  these  determinations,  except  what  arises  from 
the  false  position  in  which  refraction  places  celestial  objects.  In 
the  determination  of  right  ascensions  by  an  instrument  placed  in  the 
meridian,  this  source  of  error  is  avoided ;  but  it  remains  in  full  force 
as  to  declinations.  The  question  with  respect  to  right  ascensions, 
therefore,  resolves  itself  chiefly  (if  I  rightly  understand  M.  Wettinger) 
into  the  fact  of  its  being  both  easier  and  more  exact  to  determine 
the  difference  of  right  ascension  in  arc,  by  a  leisurely  and  direct  ob- 
servation of  the  angle  formed  by  the  two  meridians  in  which  the 
stars  lie,  than  to  infer  that  difference  of  arc  by  the  uncertain  agencv 
of  a  clock,  which  is  further  vitiated,  he  thinks,  by  the  uncertainty 
of  marking  the  exact  moments  when  the  stars  respectively  pass  the 
wires  of  the  meridian  instrument.  To  these  sources  of  error  he  adds 
that  of  the  ear  in  appreciating  the  beats  of  the  clock. 

"  M.  Wettinger  is  of  opinion,  that,  although  only  experience  can 
determine  the  degree  of  accuracy  with  which  such  an  instrument 
could  give  the  desired  results,  very  fair  estimates  may  be  formed  by 
practical  astronomers  familiar  with  the  difficulties  and  errors  of  the 
existing  methods,  of  the  probable  advantages  of  his  invention. 
Whether,  for  example,  the  effects  of  refraction  on  stars  above  a  cer- 
tain altitude,  on  their  right  ascensions  and  declinations,  are  not  suf- 
ficiently well  known  to  admit  of  such  exact  corrections  being  applied 
to  the  determinations  made  by  his  instrument,  as  would  render  their 


Royal  Astronomical  Society.  481 

results  more  worthy  of  confidence  than  those  made  with  the  existing 
instruments.  It  being  taken  into  account,  also,  that,  while  only  one 
observation  can  be  made  in  the  day  on  all  stars  which  are  not  circum- 
polar,  and  only  two  on  some  of  those  which  never  set,  with  an  in- 
strument fixed  in  the  meridian,  the  number  of  observations  which 
may  be  made  with  M.  Wettinger's  instrument  is  unlimited ;  and  as 
these  observations  might  be  made  at  all  altitudes  from  that  when 
the  stars  passed  the  meridian  to  the  moment  of  their  rising  or  setting, 
many  curious  inferences  might  possibly  be  deduced  from  it  on  the 
subject  of  refraction,  while  the  observations  might  be  so  arranged 
as  to  counteract  the  vitiating  effects  of  refraction,  and,  by  the  com- 
bination, to  give  correct  results. 

"  It  would  seem  that  this  instrument  would  be  very  useful  in  de- 
termining the  place  of  a  comet  by  direct  observation,  instead  of  in- 
ferring it,  as  is  usual,  even  with  an  equatoreal  instrument.  For  this 
purpose  any  standard  or  other  star  sufficiently  brilliant  to  bear  the 
triple  reflection  may  be  used. 

"  It  will  be  observed  in  Signor  Carlini's  report,  that,  a  doubt 
having  been  expressed  as  to  the  possibility  of  applying  the  principle 
of  this  instrument  to  the  sun,  M.  Wettinger,  in  order  to  try  the  ex- 
periment, fixed  the  small  reflector  or  speculum  of  his  model  to  the 
great  equatoreal  at  Milan,  in.  such  a  way  that,  while  Sirius  was  ob- 
served directly  by  the  telescope,  the  image  of  the  sun,  duly  darkened 
and  submitted  to  one  reflexion,  was  observed  in  the  same  apparent 
direction  ;  and  both,  as  he  informs  me,  with  such  perfect  precision, 
that  the  star  could  be  seen  on  the  disc  of  the  sun,  or  be  brought  in 
contact  with  the  limb  with  the  utmost  certainty. 

"  It  will  be  observed  that  Signor  Carlini  and  his  colleagues,  in 
their  report,  advert  to  the  multiplicity  of  parts  and  variety  of  move- 
ments in  M.  Wettinger's  instrument,  as  contrasted  with  the  fixed 
nature  and  simple  operations  of  the  large  meridian  instruments  now 
in  use.  But  still  they  appear  to  be  disposed  to  look  with  a  favourable 
eye  to  the  capabilities  of  M.  Wettinger's  invention,  and  they  seem 
anxious  that  one  of  sufficient  dimensions  should  be  made  ;  but  for  this, 
in  their  opinion,  there  are  no  means  in  Italy,  and  they  recommend 
Munich  or  Vienna.     Why  not  London  ? 

"  M.  Wettinger  is  of  opinion  that  prisms  of  glass  might  probably 
be  substituted  with  advantage  in  place  of  the  reflectors. 

"  As  I  may  probably  have  omitted  some  material  points  in  this 
explanation,  I  have  requested  M.  Wettinger  to  draw  up  a  descrip- 
tion of  it  in  Italian,  the  only  language  which  he  speaks ;  and  I  have 
asked  him  to  employ  the  same  letters  of  reference  which  I  have  used, 
so  that  the  same  sketches  may  do  for  both. 

"  I  ought  to  add,  that  M.  Wettinger  is  one  of  the  professors  of 
the  university  established  here,  and  that  he  has  long  been  highly 
esteemed  for  his  knowledge  and  ability,  and  he  is  a  person  well  ac- 
quainted both  with  the  principles  and  the  practice  of  astronomy. 

"  Should  you  wish  it,  or  should  you  think  it  would  prove  inter- 
esting to  the  Astronomical  Society,  to  see  the  model  which  M.  Wet- 
tinger has  constructed,  I  have  no  doubt  he  would  readily  allow  it  to 

Phil.  Mag.  S.  3.  Vol.  21.  No.  140.  Dec.  1842.  2  K 


482  Royal  Astronomical  Society. 

be  sent  to  England ;  or  should  you  wish  any  further  information 
respecting  it,  you  will  do  him  a  favour  by  writing  to  him  at  Malta. 
I  shall  not  be  here  above  a  month  longer,  as  I  go  on  to  Egypt  with 
my  family  in  January ;  but  M.  Wettinger  being  fixed  to  this  spot, 
will  always  be  available. — I  remain,  &c. 

"  Basil  Hall." 

II.  A  Letter  from  Professor  Henderson  to  the  Secretary,  dated 
Edinburgh,  January  31,  1842,  on  the  Determination  of  the  Parallax 
of  a  Centauri,  by  recent  Observations  made  by  Mr.  Maclear  at  the 
Cape  of  Good  Hope*. 

"  My  dear  Sir, — Within  these  few  days  I  have  received  from 
Mr.  Maclear  a  series  of  observations  of  a1  and  a2  Centauri,  made 
with  a  view  to  ascertain  the  parallax ;  and  I  find  that  they  confirm 
the  existence  of  a  parallax  amounting  to  about  one  second.  The 
observations  are  of  the  double  altitudes  of  the  stars  made  with  the 
mural  circles,  and  they  extend  from  April  16,  1839,  to  August  12, 
1840.  Twenty-six  observations  of  the  double  altitude  of  each  star 
were  made  with  the  old  circle  between  April  16  and  June  16,  1839; 
and  108  observations  of  the  double  altitude  of  a1,  and  112  of  a9, 
were  made  with  the  new  circle  between  August  4,  1839,  and  August 
12,  1840.  In  each  observation  the  star  was  observed  both  by  direct 
vision  and  by  reflexion  at  the  same  transit.  The  results  which  I 
have  obtained  are  as  follow : — 

"  From  the  272  observations  made  with  both  circles, 

Parallax  =    6-91.     Weight  147*93  observations. 
Coefficient  of  Aberration  =  20-55.  ...     142*47      ... 

"  From  the  220  observations  made  with  the  new  circle, 

Parallax  =    6*92.     Weight  138-81  observations. 
Coefficient  of  Aberration  =  20-53.         ...      12797 

"  The  observations  made  with  the  old  circle  extend  over  too  short 
a  period  to  warrant  any  results  beng  deduced  from  them  alone  for 
parallax  and  aberration  which  could  be  relied  upon. 

"  On  computing  the  observations  of  each  star  separately,  I  find 
for  a1, — 

"  From  the  134  observations  made  with  both  circles, 

Parallax  =    0-86.     Weight  70*37  observations. 
Coefficient  of  Aberration    =20-61.         ...       70*02 

"  From  the  108  observations  made  with  the  new  circle, 

Parallax  =    0*91.     Weight  65*83  observations. 
Coefficient  of  Aberration  =  20-54.         ...       63*71 

"  And  for  a-,  — 

*  Former  observations  on  this  subject  are  noticed  in  Phil.  Mag.  S.  3. 
vol.  xvi.  p.  148 ;  vol.  xviii.  p.  599. — Edit. 


Royal  Astronomical  Society.  483 

"  From  the  138  observations  made  with  both  circles, 

Parallax  =    &96.    Weight  77*55  observations. 
Coefficient  of  Aberration  =  20*48.         ...       72*44 
"  From  the  112  observations  made  with  the  new  circle, 

Parallax  =    6*93.     Weight  72*99  observations. 
Coefficient  of  Aberration  ==  20*52.         ...       66*27 

"  If  the  coefficient  of  aberration  be  assumed  =  20"*36,  as  in  the 
Astronomical  Society's  Catalogue,  then,  from  all  the  observations 
with  both  circles,  parallax  =  0"*98,  the  separate  results  for  the  two 
stars  being  0"*95  and  1"*00;  and,  from  all  the  observations  with  the 
new  circle,  parallax  =  0"*99,  the  separate  results  being  0"*98  and 
0"*99. 

"  I  believe  that  the  observations  are  still  continued  to  be  made  at 
the  Cape ;  and  I  will  write  to  Mr.  Maclear  immediately,  requesting 
him  to  send  the  additional  observations. 

"  The  two  stars  appear  to  be  approaching  each  other,  the  dif- 
ference of  declination  being  in  1826  =  18",  in  1833  =  15",  and  in 
1840  ss  11".  When  all  the  observations  are  collected,  an  attempt 
may  be  made  to  determine  the  orbits,  and  thence  the  masses  of  the 
stars. 

"  I  will  as  early  as  possible  prepare  a  detailed  memoir  on  the 
subject,  and  transmit  it  to  the  Admiralty  for  presentation  to  the 
Astronomical  Society. — I  am,  &c.  "  T.  Henuekson." 

III.  Positions  of  78  Fixed  Stars  contained  in  the  A.  S.  C,  repre- 
sented by  Mr.  Baily  as  not  determined  with  sufficient  accuracy,  de- 
duced from  Observations  made  with  the  Meridian  Circle  of  the  Ob- 
servatory of  Kremsmunster.  By  M.  Roller,  Director  of  the  Obser- 
vatory. 

IV.  Observations  of  Falling  Stars  made  at  Hereford  on  the  night 
of  Nov.  12,  1841.     By  Henry  Lawson,  Esq. 

Three  observers  were  employed  in  watching  for  these  phenomena, 
from  seven  o'clock  in  the  evening  till  half-past  four  o'clock  of  the 
following  morning,  each  taking  a  distinct  portion  of  the  heavens. 
The  whole  number  observed  was  79,  and  the  greatest  number  ob- 
served in  any  one  hour  was  20,  between  the  hours  of  three  and  four 
in  the  morning.  The  result  the  author  considers  to  be  so  far  satis- 
factory, that  it  tends  to  confirm  the  fact  of  the  appearance,  at  about 
this  period,  of  a  greater  number  of  meteors  than  usual. 

V.  A  List  of  Falling  Stars  observed  Nov.  12,  1841,  at  St.  Helena. 
By  J.  H.  Lefroy,  Esq.,  R.A.,  Director  of  the  Magnetic  Observatory  at 
Longwood. 

The  whole  number  observed  was  102,  between  the  hours  of  eight 
in  the  evening  and  five  of  the  following  morning.  The  Greenwich 
mean  solar  time  of  the  appearance  of  each  is  noted  to  the  nearest 
second,  and  the  place  of  its  appearance  as  referred  to  the  bright  stars 
nearest  it.  The  direction  of  the  motion  of  each  is  also  given,  with 
remarks  on  its  appearance,  rapidity,  and  other  circumstances  con- 
nected with  the  phenomenon. 

2K2* 


484  London  Electrical  Society. 

VI.  Path  of  the  Moon's  Shadow  over  the  Southern  part  of  France, 
the  North  of  Italy,  and  part  of  Germany,  during  the  Total  Eclipse 
of  the  Sun  on  July  7,  1842  (July  8,  Civil  Time).  By  Lieutenant 
W.  S.  Stratford,  R.N.  This  paper  will  be  found,  entire,  at  p.  346 
of  the  preceding  volume. 

VII.  A  letter  from  Professor  Hansen,  dated  March  1, 1842,  in  ac- 
knowledgement of  the  communication  of  the  Foreign  Secretary,  an- 
nouncing the  award  of  the  Society's  Gold  Medal  at  the  last  Annual 
General  Meeting. 

"  Sir, — I  have  just  now  received  your  letter,  by  which  you  an- 
nounce to  me  that  the  Royal  Astronomical  Society  have  honoured  me 
with  their  Gold  Medal.  I  recognise  in  it  a  valuable  sign  of  the  kind 
attention  of  this  Society  towards  me  and  my  labours ;  and  I  beg  you 
to  present  to  them  my  sincerest  thanks. 

"  Pray  have  the  goodness  to  allow  the  medal  to  be  sent  to  M. 
Prsetorius,  Secretary  and  Librarian  of  His  Royal  Highness  Prince 
Albert,  who  will  undertake  to  send  it  to  me. 

"  Of  late  my  labours  in  the  lunar  theory  have  been  considerably 
advanced.  The  calculation  of  the  perturbations  is  finished,  and  I  am 
now  engaged  on  the  calculation  of  provisional  tables  for  the  purpose 
of  comparing  my  results  with  observations,  and  of  determining  the 
correction  of  the  elliptic  elements  which  result  from  them.  I  am 
now  giving  to  these  tables  the  necessary  extension,  that  they  may 
afterwards  serve  as  definite  tables,  after  having  applied  to  them  the 
necessary  corrections  which  are  required  by  the  new  determination 
of  the  elliptic  elements.  To  combine  with  exactness  in  these  tables 
the  most  convenient  mode  of  calculating  the  places  of  the  moon,  I 
have  chosen  the  form  that  M.  Carlini  has  given  to  the  tables  of  the 
sun,  as  much  as  it  is  possible  to  do  so.  However,  the  labour  of 
calculation  of  the  tables  themselves  is  much  increased  by  this  arrange- 
ment. 

"  Repeating  my  request  that  you  will  present  my  respects  to  the 
Royal  Astronomical  Society,  I  beg  you  will  accept  the  sentiment  of 
high  consideration  with  which  I  have  the  honour  to  be,  &c. 

"  P.  A.  Hansen." 


LONDON  ELECTRICAL  SOCIETY. 

[Continued  from  p.  405.] 

Nov.  15, 1842. — A  note  from  Mr.  "Weekes  was  read,  accompanied 
by  specimens  of  Acarus  galvanicus,  developed  in  solution  of  ferro- 
cyanuret  of  potash. 

The  following  notices  were  communicated  by  W.  G.  Lettsom, 
Esq.,  M.E.S.  : — 1st.  Of  a  new  and  important  application  of  gal- 
vanism, by  which  Jacobi  succeeds  in  extracting  gold  and  silver  from 
their  respective  ores.  2nd.  Of  the  employment  of  electro-magnetism 
for  the  movement  of  machinery,  in  which  it  is  stated  that  M. 
Wagner,  to  whom  the  German  Diet  promised  100,000  florins  if  his 
plan  really  succeeded,  now  reports  that  he  has  surmounted  all  diffi- 
culties.    3rd.  On  M.  Peclet's  new  condenser,  an  instrument  calcu- 


Cambridge  Philosophical  Society.  485 

lated  to  test  the  most  minute  amount  of  electric  tension.  It  con- 
sists of  an  electroscope  surmounted  by  a  disc  A  of  glass  coated 
with  gold  and  varnished  on  its  upper  surface  ;  the  disc  B,  varnished 
on  both  sides,  is  placed  on  this ;  it  has  a  glass  handle ;  the  disc  C 
has  a  handle  of  glass  tube  so  constructed  that  the  handle  of  B  can 
pass  through  it.  The  delicacy  of  this  instrument  was  shown  by  the 
results  which  followed  the  touching  of  the  upper  disc  with  an  iron 
wire  once,  twice,  thrice,  four,  five,  and  ten  times. 

A  paper  by  J.  P.  Gassiot,  Esq.,  F.R.S.  M.E.S.  &c,  was  then 
read,  "On  the  Polarity  of  the  Voltaic  Battery."  After  alluding  to 
the  confused  descriptions  of  voltaic  batteries  which  have  emanated 
from  the  varied  modes  of  arranging  the  elements,  Mr.  Gassiot  men- 
tions that  the  electric  tension  of  the  water  battery  has  been  de- 
scribed as  differing  from  that  of  other  battles ;  the  end  we  have 
been  accustomed  to  regard  as  positive  is  designated  resinous,  and 
the  other  vitreous ;  and  this  result  presented  itself  to  him  in  his 
early  experiments;  upon  closer  investigation,  however,  it  appears 
that  these  conflicting  results  are  due  to  want  of  attention  to  the 
mode  of  manipulating  with  the  electroscope.  When  the  excited  rod 
is  applied  to  the  side  of  this  instrument,  the  leaves  are  affected  in  a 
manner  precisely  the  reverse  of  what  happens  when  it  is  applied  above. 
The  anomalous  results  occur  in  the  former  case,  and  are  due  to  the 
effect  of  the  glass  rod  on  the  instrument  itself,  disturbing  not  only 
the  natural  electricity  contained  in  the  leaves,  but  also  the  surplus 
acquired  by  being  in  contact  with,  or  charged  by,  the  battery.  The 
charge  is  driven  upwards  into  the  plate,  and  the  leaves  approach  the 
normal  condition.  When  the  rod  is  applied  above  the  converse 
occurs.  These  experiments  were  made  with  a  new  double  electro- 
scope. In  conclusion,  the  author  offers  a  few  remarks  on  electrical 
nomenclature,  and  conceives  that  so  long  as  we  are  content  to  con- 
tinue the  terms  positive  and  negative,  vitreous  and  resinous,  in  ap- 
plication to  the  machine,  we  should  not  object  to  use  them  in 
reference  to  the  battery. 

Mr.  Walker  then  concluded  the  reading  of  his  translation  of  M. 
Becquerel's  paper  "  On  the  Electro-Chemical  properties  of  Gold,"  in 
which  are  given  some  interesting  applications  of  theory  to  practice. 
In  extracting  ore  from  a  solution  of  several  metals,  another  solution 
is  made  of  all  the  metals  but  that  one ;  it  is  made  as  nearly  as  pos- 
sible of  the  same  specific  gravity  ;  the  two  form  the  exciting  liquids 
to  a  single  cell  arrangement,  and  the  effect  is  the  release  of  the  metal 
required.  Modifications  of  the  same  principle  are  applied  to  gild- 
ing, the  author  giving  the  preference  to  the  single  cell  apparatus. 

Mr.  Weekes's  Electro- Meteorological  Register  for  October  was 
read. 


CAMBRIDGE  PHILOSOPHICAL  SOCIETY. 

Nov.  14,  1842. — Professor  Fisher  read  a  paper  on  the  Develop- 
ment of  the  Spinal  or  Intervertebral  Ganglia,  and  on  various  Mal- 
formations of  the  Nervous  System.  This  communication  was  one  of 


486  Cambridge  Philosophical  Society. 

several  which  Professor  Fisher  intends  to  bring  forward,  the  general 
object  of  which  may  be  thus  expressed  : — 

Researches  on  certain  forms  of  disease,  considered  in  their  con- 
nexion with  the  process  of  formation,  the  growth  and  maintenance, 
and  the  decline  of  the  human  frame. 

The  tendency  which  the  human  ceconomy  has  to  accomplish  the 
scheme  of  its  organic  existence,  is  the  vital  law  by  which  the  author 
has  been  directed  in  these  researches.  Deriving  his  method  from  an 
idea  of  Galen,  Professor  Fisher  distinguishes  in  an  organ  two  pro- 
cesses, the  plastic  and  the  functional.  Under  the  first  he  comprises 
the  formation,  the  growth,  and  maintenance  of  an  organ,  as  well  as 
the  alterations  of  structure,  normal  or  anormal,  which  it  may  pre- 
sent. Under  the  second,  those  acts  of  an  organ  by  which  it  effects 
results  which  have  reference  to  the  ceconomy. 

The  physiological  portion  of  Professor  Fisher's  communication 
consisted  of  an  account  of  some  embryological  researches  he  had 
made  on  the  development  of  the  spinal  ganglia,  in  order  to  throw 
light  on  the  anomalous  conditions  which  some  of  them  present  in 
Spina  bifida,  when  that  disease  is  limited  to  the  lower  region  of  the 
spinal  column*.  Before  stating  the  result  of  these  researches,  it 
may  not  be  inappropriate  to  mention,  that  those  anomalous  con- 
ditions consist  in  a  coalescence  of  the  last  lumbar  with  the  first 
sacral  ganglion,  or  in  a  coalescence  of  some  of  the  sacral  ganglia 
with  each  other  f.  In  some  instances  a  comparatively  strong  band 
is  found  to  pass  from  the  fourth  to  the  fifth  lumbar  ganglion  J. 

Finding  no  mention  made  of  the  development  of  the  spinal 
ganglia  by  the  physiologists  whose  works  Professor  Fisher  con- 
sulted, he  was  induced  to  make  researches  on  the  subject,  of  which 
the  following  statement  comprises  the  general  results  : — 

That  the  white,  rounded  or  pyriform  bodies  which  are  situated  on 
the  side  of  the  furrow  which  occupies  the  site  of  the  future  spinal 
cord  of  the  embryon  constitutes  the  rudiments  of  the  spinal  or 
intervertebral  •  ganglia  § . 

*  In  every  case  of  Spina  bifida  which  the  author  has  met  with  affecting 
the  upper  part  of  the  spinal  column,  it  was  accompanied  by  a  defective 
formation  of  the  head. 

f  The  author  has  not  met  with  any  instance  in  which  this  coalescence 
did  not  exist.  He  has  now  examined  sixteen  cases.  In  one  case  the  sub- 
ject presented  a  club-foot,  on  the  same  side  as  that  on  which  the  two  first 
sacral  ganglia  were  united.  He  could  not  recognise  any  trace  of  the  anterior 
roots  on  the  united  ganglia,  but  unfortunately  the  thigh  was  so  lacerated 
as  not  to  enable  him  to  ascertain  with  any  degree  of  security  whether  any 
part  of  the  nervous  or  muscular  system  of  the  limb  was  deficient  or  not. 
In  the  same  case  the  fourth  sacral  ganglia  on  each  side  were  united  into 
one  mass,  which  was  supplied  by  a  single  artery.  In  this  case,  as  indeed 
in  all  others  which  Professor  Fisher  has  observed,  the  lumbar  and  sacral 
nerves  presented,  as  they  emerged  from  their  respective  foramina,  a  na- 
tural appearance.     The  sacral  plexus  always  seemed  to  be  duly  formed. 

X  The  author  at  first  thought  this  band  might  be  a  vessel,  but  careful 
dissection  convinced  him  that  it  was  continuous  with  the  sheath  of  the 
ganglia  with  which  it  was  connected.  Its  internal  structure  presented  a 
granular  appearance. 

§  Professor  Fisher,  at  the  commencement  of  these  researches,  was  im- 


Cambridge  Philosophical  Society.  487 

That  whilst  the  edges  of  the  furrow  are  closing,  a  -white  line 
having  a  filamentous  appearance  arises  between  it  and  each  ganglion, 
the  connexion  of  which  with  the  central  parts  corresponds  with  the 
swellings  which  give  to  those  parts  a  sinuous  appearance. 

That  another  white  line  arises  between  the  ganglia,  and  connects 
them  together,  so  as  to  cause  them  to  offer  collectively  an  arrange- 
ment somewhat  analogous  to  that  which  the  ganglia  of  some  inver- 
tebrate animals  present. 

That  another  line  appears  to  proceed  from  each  ganglion  exter- 
nally, and  to  join  one  which  runs  parallel  with  the  axis  of  the  body 
and  communicates  with  the  cardiac  ganglion. 

Resuming  the  pathological  part  of  his  subject,  Professor  Fisher 
gave  the  following  statement  of  the  views  he  entertained  on  the 
subject  of  Spina  bifida,  when  that  disease  is  situated  in  the  lumbo- 
sacral region* : — 

That  the  coalescence  already  described  of  the  ganglia  constitutes 
the  primary  irregularity  to  which  all  the  others  that  the  disease  pre- 
sents may  be  directly  or  indirectly  referred. 

That  this  coalescence  is  favoured  by  the  position  those  ganglia 
occupy,  and  by  their  volume,  the  comparative  greatness  of  which 
may  be  due  to  their  connexion  with  the  sacral  plexus  f. 

That  the  roots  of  the  nerves  appertaining  to  the  united  ganglia, 
by  virtue  of  their  passing  through  the  dura  mater  in  one  bundle, 
become  so  irregularly  connected  with- the  pia  mater  of  the  cord,  as 
to  give  rise  to  adhesions  between  that  membrane  and  the  arachnoid, 
and  between  the  latter  and  the  dura  mater. 

That  this  disordered  condition  of  the  pia  mater  has  for  its  conse- 
quence the  anomalous  position  of  the  cord  (which  always  adheres 
to  the  inner  surface  of  the  posterior  wall  of  the  tumour),  and  even 
in  some  instances  a  deficient  development  of  that  organ. 

That  the  beginning  of  the  bifid  state  of  the  osseous  canal  corre- 
sponds above  to  the  point  .where  the  cord  becomes  attached  to  the 
posterior  wall  of  the  tumour  J. 

pressed  with  the  feeling,  that  since  his  results  differed  from  those  of  other 
embryologists,  he  might  be  mistaken  about  the  nature  of  these  bodies.  He 
finds,  however,  that  they  are  confirmed  in  part  by  the  observations  of  the 
late  Professor  Rolando,  and  therefore  .he  has  felt  more  confidence  in  com- 
municating them.  But  whether  the  observations  he  has  made,  or  the  con- 
clusions he  has  drawn  from  them,  be  correct  or  not,  the  development  of 
the  spinal  or  intervertebral  ganglia  ought  not  to  be  lost  sight  of. 

*  Although  these  views  coincide  with  those  the  author  communicated  on 
a  previous  occasion,  and  which  were  recorded  in  the  London  and  Edin- 
burgh Philosophical  Magazine  (vol.  x.  p.  316),  still  it  may  not  be  con- 
sidered inappropriate  if  they  be  presented  again,  in  association  with  the 
additional  matter  he  has  brought  forward. 

f  The  spinal  ganglia  are,  at  least  about  the  middle  of  foetal  life,  richly 
supplied  with  blood-vessels,  which  may  also  assist,  along  with  the  hyper- 
trophy of  the  ganglia,  in  favouring  their  coalescence. 

%  In  all  cases  of  Spina  bifida,  the  defective  formation  of  the  osseous 
canal  corresponds  with  that  of  the  cord ;  where  the  latter  assumes  its 
natural  conformation,  the  canal  becomes  complete. 


488  Intelligence  and  Miscellaneous  Articles. 

That  the  branches  of  the  lumbar  and  sacral  vertebrae  are  not  ab- 
sent in  the  region  affected,  but  are  more  or  less  everted  by  the  pre- 
sence of  the  tumour. 

The  researches  which  Professor  Fisher  has  made  on  the  defective 
formation  of  the  spinal  cord  have  led  him  to  adopt  the  following 
general  view  regarding  the  plastic  process  of  that  organ  : 

That  although  the  spinal  cord  possesses,  like  every  other  organ,  a 
plastic  process  peculiar  to  itself,  yet  that  process  may  be  so  influ- 
enced by  the  anomalous  condition  of  some  of  the  roots  of  the  spinal 
nerves  as  to  lead  to  a  partial  malformation,  or  even  to  a  partial  de- 
ficiency of  the  organ  *. 

The  following  are  the  therapeutical  inferences  that  Professor 
Fisher  has  drawn  from  his  investigations  of  the  disease  in  ques- 
tion : — 

That  as  the  fluid  which  the  tumour  contains  is  a  natural  product  f, 
and  destined  by  its  pressure  to  protect  the  parts  with  which  it  is  in 
relation,  the  removal  of  it,  either  by  a  natural  or  artificial  opening, 
is  to  be  avoided ;  for  an  opening  is  not  only  liable  to  occasion  in- 
flammation of  the  lining  membrane  of  the  tumour,  by  the  introduc- 
tion of  air  and  by  other  causes,  but  also  to  allow  the  continual 
escape  of  the  fluid,  so  as  to  lead  to  death,  either  by  exhaustion  or 
by  depriving  the  blood  of  its  serous  fluid ;  for  according  to  an  ob- 
servation recorded  by  Morgagni,  and  one  made  by  Professor  Fisher 
himself,  the  suppression  of  urinary  secretion  coincided  with  the  con- 
stant discharge  of  the  fluid. 

That  if,  in  puncturing  the  tumour,  the  operation  be  performed  in 
the  upper  and  middle  part  of  it,  the  spinal  cord  will  almost  neces- 
sarily be  wounded. 

That  if  the  skin  covering  the  tumour  be  in  a  natural  state,  then 
an  equable  pressure,  in  the  application  of  which  regard  must  be  had 
to  the  situation  of  the  spinal  cord,  may  be  used  with  advantage ;  but 
if  the  walls  of  the  tumour  be  thin  and  membranous,  then  astringent 
lotions,  tending  to  corrugate  them,  may  be  applied ;  in  this  case, 
however,  the  disease  generally  proves  fatal. 


LXXXIV.    Intelligence  and  Miscellaneous  Articles. 

USE  OF  SULPHATE  OF  AMMONIA  IN  AGRICULTURE^. 

T^OR  the  full  development  of  the  capacity  of  the  soil,  and  to 
•*•       afford  a  greater  amount  of  nitrogen  'than  what  is  af- 

*  The  author  has  applied  the  idea  involved  in  this  view  to  the  considera- 
tion of  Anencephalus,  and  it  is  his  intention  to  communicate,  on  another 
occasion,  the  results  of  his  observations  on  that  subject,  and  on  the  de- 
fective formation  of  the  upper  part  of  the  spinal  column. 

t  The  fluid  is  secreted  by  the  pia  mater,  but  its  quantity  is  probably  in- 
creased by  the  veins,  which  often  appear  unusually  distended,  a  condition 
that  may  be  owing  to  the  want  of  resistance  in  the  containing  parts.  ,  As 
regards  the  author's  views  on  the  subject  of  this  secretion,  see  Phil.  Mag. 
S.  3.  vol.  x.  p.  316. 

X  Communicated  by  the  Engineer  of  the  Chartered  Gas  Company. 


Intelligence  and  Miscellaneous  Articles.  489 

forded  either  by  the  ordinary  manure,  or  the  ammonia  &c.  of 
the  atmosphere,  sulphate  of  ammonia  has  been  introduced, 
and  found  to  be  a  most  valuable  auxiliary,  as  a  top  dressing,  to 
the  farmer. 

It  has  been  found  to  impart  a  greater  degree  of  fructifica- 
tion to  grass,  wheat,  and  other  grain,  than  any  other  dressing 
yet  discovered,  and  at  a  less  cost  by  50  per  cent. 

The  mode  of  application  as  adopted  by  Mr.  C.  Hall  of 
Havering-atte-Bower,  Essex,  is  as  follows : — 

Having  selected  several  fields  of  grass,  peas,  turneps,  and 
wheat,  he  had  sown  broad  cast  on  parts  of  these  fields  quan- 
tities at  the  cost  of  5s.  3d.,  lis.  4<d.  and  21s.  per  acre;  the 
sulphate  having  cost  him  1 7s.  per  cwt. 

The  produce  was  kept  and  threshed  separately,  when  the 
increase  from  the  wheat  land  was  found  to  be  as  follows : — 

The  part  that  was  sown  at  the  rate  of  5s.  3d.  per  acre  gave 
an  increase  of  3  bushels;  lis.  4<d.  gave  6  bushels,  and  21s. 
upwards  of  9  bushels,  besides  a  considerable  increase  of  straw. 

CHLORIDE  OF  GOLD  AS  A  TEST  OF  CERTAIN  VEGETABLE 
ALKALIES. 

MM.  Larocque  and  Thibierge  find,  that  perchloride  of  gold  is  a 
more  decisive  test  of  certain  vegetable  alkalies,  than  the  double  chlo- 
ride of  sodium  and  gold  already  employed  for  this  purpose.  The 
following  are  the  colours  of  the  precipitates  which  it  produces  with 
the  salts  of  the  annexed  alkalies  dissolved  in  water  : — Quina,  buff- 
coloured  :  Cinchonia,  sulphur-yellow  :  Morphia,  yellow,  then  bluish, 
and  lastly  violet ;  in  this  last  state  the  gold  is  reduced,  and  the  pre- 
cipitate is  insoluble  in  water,  alcohol,  the  caustic  alkalies,  and  sul- 
phuric, nitric  or  hydrochloric  acids ;  it  forms  with  aqua  regia  a  so- 
lution which  is  precipitated  by  protosulphate  of  iron  :  Brucia,  milk-, 
coffee-,  and  then  chocolate-brown  :  Strychnia,  canary-yellow  :  Vera- 
tria,  slightly  greenish  yellow. 

All  these  precipitates,  with  the  exception  mentioned,  are  very 
soluble  in  alcohol,  insoluble  in  aether,  and  slightly  soluble  in  water. 
These  precipitates  appear  to  be  combinations  of  gold,  chlorine  and 
the  vegetable  alkali,  for  their  alcoholic  solutions  treated  with  tannin 
give  a  greenish  blue  precipitate  of  reduced  gold ;  if  the  solution  be 
filtered,  and  the  alcohol  be  evaporated  by  heat,  a  precipitate  of  tan- 
nate  of  the  alkali  employed  is  formed.  The  liquor  again  filtered, 
gives  with  nitrate  of  silver  a  white  precipitate  insoluble  in  nitric  acid, 
but  soluble  in  ammonia. 

Among  the  reactions  of  chloride  of  gold,  there  are  two  which  to 
ihe  authors  appear  to  be  especially  important,  they  are  those  which 
occur  with  morphia  and  brucia ;  they  are  sufficiently  marked  to  pre- 
vent these  alkalies  from  being  mistaken  for  each  other,  and  also 
yield  pretty  good  characteristics  for  distinguishing  brucia  from 
strychnia. 


490  Intelligence  and  Miscellaneous  Articles. 

MM.  Larocque  and  Thibierge  detail  also  various  experiments  on  the 
modes  of  detecting  opium  proposed  by  Dr.  Christison,and  they  mention 
that  their  results  differ  much  from  his.  They  state  that  these  dif- 
ferences may  arise  from  three  causes, — 1st,  the  inequality  of  the  com- 
position of  the  opium  of  commerce ;  2ndly,  the  analytical  process  em- 
ployed by  Dr.  Christison,  which  consisted  in  decomposing  the  meco- 
nate  of  lead  by  sulphuretted  hydrogen — this  the  authors  show  fre- 
quently masks  the  meconic  acid,  and  that  it  could  only  be  detected 
by  decomposing  the  meconate  of  lead  with  dilute  sulphuric  acid ; 
3rdly,  the  variable  nature  of  the  liquids  with  which  opium  is  mixed. 

The  authors  have  also,  as  the  results  of  their  experiments,  arrived 
at  the  following  conclusions  : — 

1st.  By  the  aid  of  reagents  it  is  possible  to  determine  the  pre. 
sence  of  morphia,  strychnia  and  brucia  in  substances,  which,*after 
being  mixed  with  the  salts  of  these  alkalies,  have  undergone  the 
vinous,  acetic  or  putrefactive  fermentation.  M.  Orfila  has  already 
shown  that  the  putrefactive  fermentation  does  not  alter  morphia. 

2ndly.  Crystallized  iodic  acid,  or  a  concentrated  solution  of  this 
acid,  is  susceptible  of  being  decomposed  by  neutral  azotized  bodies  ; 
but  a  dilute  solution  of  this  acid  cannot  be  decomposed  by  them  un- 
less there  be  added  concentrated  sulphuric  acid,  crystallizable  acetic 
acid,  oxalic,  citric  or  tartaric  acid. 

3rdly.  Iodic  acid  should  not  be  employed  as  a  test  of  morphia 
without  the  greatest  caution. 

4thly.  Perchloride  of  gold  produces  such  effects  with  the  vegetable 
alkalies,  as  serve  to  distinguish  morphia,  brucia  and  strychnia  from 
each  other. 

5thly.  The  reagents  on  which  the  greatest  reliance  may  be  placed 
as  tests  of  morphia  are,  nitric  acid,  neutral  perchloride  of  iron,  and 
perchloride  of  gold. 

6thly.  By  the  use  of  reagents,  morphia  which  has  been  mixed  with 
beer,  soup  or  milk  may  be  detected. 

7thly.  It  is  also  easy  to  prove  by  reagents  the  presence  of  meconic 
acid  in  soup  or  milk,  especially  when  the  meconate  of  lead  is  decom- 
posed by  dilute  sulphuric  acid. — Journal  de  Chimie  Medicate,  Octo- 
bre  1842. 


NON-DECOMPOSITION  OF  VEGETABLE   ALKALIES  BY  EXPOSURE 
TO  FERMENTING  BODIES. 

It  appeared  to  MM.  Larocque  and  Thibierge  a  subject  of  some 
interest  to  determine  by  experiment,  whether  the  vegetable  alkalies 
suffered  decomposition  when  in  contact  with  fermenting  substances. 
It  had,  indeed,  been]  proved  by  Orfila  and  Lesueur  that  acetate  of 
morphia  suffered  no  change  discoverable  by  reagents,  under  these 
circumstances ;  and  M.  Merck  detected  strychnia,  morphia  and 
brucia  after  they  had  been  exposed  to  fermenting  animal  and  ve- 
getable matters  during  twenty  days. 

The  following  experiments  were  made  by  MM.  Larocque  and 
Thibierge: — 


Intelligence  and  Miscellaneous  Articles.  491 

To  3080  grains  of  blood  there  were  added  5*14  grains  of  [sul- 
phate of  ?]  brucia ;  this  mixture  was  exposed  to  the  air  from  the 
2nd  of  June  to  the  3rd  of  August ;  at  this  period  the  blood  was  pu- 
trefying and  fetid.  It  was  evaporated  to  dryness  ;  the  residue  was 
treated  with  boiling  alcohol ;  the  solution  obtained  was  filtered  and 
evaporated  to  dryness,  and  treated  with  water  acidulated  with  ace- 
tic acid.  The  solution  thus  procured  was  filtered  and  evaporated 
to  a  syrupy  consistence.  In  this  state  it  was  reddened  by  nitric  acid, 
and  become  of  a  violet  tint  by  the  successive  application  of  nitric 
acid  and  protochloride  of  tin. 

Mixtures  of  the  following  substances  were  made  on  the  2nd  of 
June  : — 7700  grains  of  distilled  water,  154  grains  of  yeast,  and  462 
grains  of  sugar.  To  four  such  mixtures  were  separately  added  5*14 
grains  of  sulphate  of  brucia,  5-14  grains  of  sulphate  of  strychnia, 
and  5*14  grains  of  acetate  of  morphia.  These  mixtures  soon  began 
to  ferment,  and  when  after  standing  several  days  the  evolution  of 
carbonic  acid  had  ceased,  they  were  evaporated  to  dryness,  then 
treated  with  boiling  alcohol,  and  after  evaporating  the  spirit,  the 
residue  was  treated  with  water  acidulated  with  acetic  acid,  and  in 
this  liquor,  evaporated  to  a  syrupy  consistence,  the  characteristics  of 
the  alkali  introduced  before  fermentation  were  determinable. 

Some  red  wine  holding  hydrochlorate  of  morphia  in  solution  had 
been  kept  in  a  bottle  loosely  corked  from  July  1841  to  the  15  th  of 
June  1842  ;  the  liquid  exhaled  a  strong  odour  of  acetic  acid  ;  after 
treating  in  the  manner  above  described,  and  decolorized  by  animal 
charcoal,  it  did  not  yield  crystals,  but  by  evaporation  to  a  syrupy 
consistence  it  gave  a  residue  which  was  reddened  by  nitric  acid,  ren- 
dered blue  by  perchloride  of  iron,  was  precipitated  by  tannin,  and 
reduced  the  chloride  of  gold. — Ibid. 


PREPARATION  AND  COMPOSITION  OF  PEPSIN. 

In  order  to  prepare  pepsin  in  quantity,  M.  Vogel,  jun.  employed 
the  following  process  : — The  glandular  skin  of  the  fresh  stomach  of 
the  hog  was  separated  from  the  serous  part,  and  after  having  cut 
it  into  small  pieces  it  was  treated  with  cold  distilled  water ;  after 
twenty-four  hours'  immersion,  the  water  was  poured  off  and  fresh 
portions  added.  This  operation  was  repeated  dujring  several  days, 
until  a  putrid  odour  was  perceptible.  The  aqueous  infusion  thus 
obtained  was  precipitated  by  acetate  of  lead,  the  white  ftocculent 
precipitate  formed  containing  the  pepsin  mixed  with  much  albu- 
men;  this  precipitate  being  diffused  through  water,  it  was  decomposed 
by  hydrosulphuric  acid  gas.  When  the  liquor  is  filtered,  the  solu- 
tion contains  pepsin  and  sulphuric  acid,  while  coagulated  albumen 
and  sulphuret  of  lead  remain  on  the  filter.  A  very  small  quantity 
of  hydrochloric  acid,  added  to  the  solution'of  pepsin  and  acetic  acid, 
is  sufficient  to  render  it  capable  of  artificial  digestion. 

In  order  to  procure  solid  pepsin,  the  filtered  liquor  must  be  eva- 
porated to  a  syrupy  consistence,  carefully  avoiding  ebullition,  and 
afterwards  adding  absolute  alcohol  to  it.     After  some  time  a  whitish 


492  Intelligence  and  Miscellaneous  Articles. 

bulky  precipitate  is  formed,  which  is  to  be  dried  by  exposure  to  the 
air ;  and  it  is  then  a  yellowish  viscid  mass  of  a  peculiar  animal 
odour  and  a  disagreeable  taste.  Pepsin  thus  obtained  has  an  acid 
reaction,  because  it  always  contains  a  small  quantity  of  acetic  acid,  to 
deprive  it  of  which  various  processes  were  tried,  and  that  which  suc- 
ceeded was  heating  it  in  a  salt-water  bath  for  some  hours,  by  which 
a  white  powder  soluble  in  water  and  possessing  no  acid  reaction  was 
obtained.  It  is  to  be  remembered  that  pepsin  loses  some  of  its 
power  of  assisting  digestion  by  the  action  of  a  high  temperature,  but 
as  it  is  not  at  the  same  time  altered  in  its  chemical  constitution,  M. 
Vogel  employed  it  for  analysis;  the  mean  of  several  experiments  gave 

Hydrogen 5*666 

Carbon 57*718 

Oxygen 16-064 

Azote 21-088 

100-536 
M.  Vogel  remarks,  that  the  results  of  this  analysis  show  that  pepsin 
is  not  identical  with  modified  albumen,  as  has  been  supposed ;  he 
further  states  that  the  action  of  pepsin  in  digestion  may  be  com- 
pared to  that  of  disastase,  which  changes  fecula  into  grape  sugar, 
without  itself  undergoing  any  alteration ;  this  opinion  was  supported 
by  the  fact,  that  of  two  grains  of  pepsin  which  had  acted  upon  dressed 
beef  so  as  completely  to  dissolve  it,  1* 98  grain  was  recovered. 

The  pepsin  of  the  sheep  possessed  only  in  a  slight  degree  the  power 
of  favouring  digestion. — Journ.  de  Pkarm.  et  de  Chim.,  Oct.  1842. 


ACTION  OF  CHLORIDES  ON  SOME  MERCURIAL  COMPOUNDS.  BY 
M.  MIALHE  *. 
A  solution  of  60  parts  of  common  salt,  and  60  of  sal-ammoniac,  is 
termed  by  M.  Mialhe  the  assay  liquor :  in  this  60  parts  of  various 
mercurial  compounds  were  digested,  during  twenty-four  hours,  at 
the  temperature  of  the  air,  and  in  the  heat  of  a  stove  ;  the  former 
varying  from  59°  to  68°  Fahr.,  and  the  latter  from  104°  to  122°  Fahr. 

I.  Protobromide  of  Mercury. — The  alkaline  chlorides  behave  with 
this  salt  as  with  calomel,  with  this  difference  only,  that  out  of  the 
contact  of  the  air  the  small  proportion  of  the  bisalt  of  mercury  which 
is  formed  is,  at  least  momentarily,  bibromide  and  not  bichloride  of 
mercury;  whereas,  while  reacting  in  the  presence  of  air,  the  greatest 
proportion  of  the  mercurial  bisalt  formed  is  bichloride. 

1st  Experiment. — At  the  temperature  of  the  air,  corrosive  subli- 
mate produced  0-6  part. 

2nd  Experiment. — By  the  heat  of  a  stove,  corrosive  sublimate  pro- 
duced 1*5  part. 

II.  Protiodide  of  Mercury. — This  is  one  of  the  mercurial  salts  in 
which  the  solution  of  alkaline  chlorides  acts  with  the  least  intensity. 

1st  Experiment. — At  the  temperature  of  the  air,  corrosive  subli- 
mate produced  0'5  part. 

*  M.  Mialhe's  researches  on  the  action  of  chlorides  upon  protochloride 
of  mercury  will  be  found  at  p.  320  of  the  present  volume. 


Intelligence  and  Miscellaneous  Articles.  493 

2nd  Experiment. — By  the  heat  of  a  stove,  corrosive  sublimate  pro- 
duced 0*6  part. 

III.  Binoxide  of  Mercury. — This  substance  is  scarcely  at  all  solu- 
ble in  water,  and  yet  it  produces  a  considerable  proportion  of  corro- 
sive sublimate  with  the  alkaline  chlorides. 

1st  Experiment. — At  the  temperature  of  the  air,  corrosive  subli- 
mate produced  4' 7  parts. 

2nd  Experiment. — By  the  heat  of  a  stove,  corrosive  sublimate  pro- 
duced 15  4  parts. 

The  quantity  of  bichloride  of  mercury  obtained  by  this  last  reac- 
tion is  certainly  very  considerable,  and  nevertheless  it  was  nearly 
the  same  with  a  much  smaller  quantity  of  the  binoxide,  the  greater 
part  of  which  remained  unacted  upon. 

The  reaction  which  takes  place  between  the  binoxide  of  mercury 
and  the  alkaline  chlorides  is  certainly  remarkable ;  it  is  however 
very  easily  explained.  The  oxide  of  mercury  behaves  with  the  al- 
kaline chlorides  exactly  in  the  same  manner  as  the  oxides  of  lead 
and  silver,  that  is  to  say,  by  simple  substitution  between  the  chlo- 
rine and  the  oxygen  there  are  produced  bichloride  of  mercury  and 
an  alkaline  oxide.  It  is  at  first  more  difficult  to  account  for  the 
non-decomposition  of  the  corrosive  sublimate  by  the  alkali  produced. 
M.  Mialhe  accounts  for  this  by  the  unquestionable  affinity  existing 
between  bichloride  of  mercury  and  the  alkaline  chlorides.  It  is  at  any 
rate  certain  that  magnesia,  which  decomposes  sublimate  readily,  has 
no  action  upon  it  when  combined  with  excess  of  an  alkaline  chloride. 

IV.  Black  Oxide  of  Mercury. — The  experiments  of  M.  Guibourt 
have  proved  that  this  compound  is  not  a  true  protoxide,  but  a  mix- 
ture in  definite  proportions  of  binoxide  of  mercury  and  metallic 
mercury.  Nevertheless  its  reactions  with  the  alkaline  chlorides 
more  nearly  resemble  those  which  are  produced  with  the  compounds 
containing  protoxide  of  mercury  than  the  peroxide.  This  fact,  how- 
ever, cannot  be  considered  as  singular,  it  being  well  known  that 
black  oxide  of  mercury  yields  salts  with  most  acids  which  really 
contain  the  protoxide  of  the  metal. 

1st  Experiment. — At  the  temperature  of  the  air,  sublimate  pro- 
duced 1*1  part. 

2nd  Experiment. — By  the  heat  of  the  stove,  sublimate  produced 
1*9  part. 

V.  Protosalts  of  Mercury. — The  action  of  the  alkaline  chlorides 
upon  these  is  always  the  same ;  protochloride  of  mercury  is  at  first 
formed,  which  acts,  as  has  been  already  described,  when  alkaline 
chlorides  are  present. 

The  following  protosalts,  employed  in  the  quantities  already  stated 
with  the  assay  liquor,  gave  the  annexed  proportions  of  sublimate  : — 
Temperature  of  the  Air.  Stove  Heat. 

Protonitrate 0"4  part.  1*3  part. 

Protosulphate     0*7   ...         .  1*4-    ... 

Protoacetate 0*8  ...  \'X    ... 

Prototartrate 04  ...  0"8    ... 

VI.  Bisalts  of  Mercury . — All  the  salts  of  binoxide  of  mercury, 
when  in  contact  with  the  alkaline  chlorides,  immediately  yield  cor- 


494-  Intelligence  and  Miscellaneous  Articles. 

rosive  sublimate  and  a  new  alkaline  salt  by  double  decomposition ; 
but  as  this  reaction  is  not  always  perceptible,  the  following  experi- 
ments, among  others,  were  performed  to  prove  it. 

Biniodide  of  Mercury. — Is  chlorine  under  certain  circumstances 
capable  of  separating  iodine  from  its  combination  with  mercury  ? 
Do  the  alkaline  chlorides,  when  reacting  on  the  biniodide  of  mer- 
cury, produce  corrosive  sublimate  ? 

1st  Experiment. — At  the  temperature  of  the  air,  mercurial  salt 
dissolved  11  parts. 

2nd  Experiment. — By  the  heat  of  the  stove,  mercurial  salt  dis- 
solved 19*3  parts. 

When  it  is  recollected  how  slightly  biniodide  of  mercury  is  soluble 
in  water,  and  considering  the  enormous  quantity  of  bisalt  here  shown 
to  exist  in  the  solution  of  the  alkaline  chlorides,  it  is  difficult  not  to 
suppose  that  a  portion  at  least  of  the  mercurial  salt  is  in  the  state  of 
corrosive  sublimate. 

VII.  Bicyanide  of  Mercury  is  decomposed  by  the  alkaline  chlo- 
rides, and  converted  into  corrosive  sublimate ;  it  is,  however,  worthy 
of  remark,  that  potash,  soda,  hydrosulphuric  acid,  free  or  combined,  a 
plate  of  copper  and  Smithson's  pile,  are  almost  the  only  reagents  which 
discover  the  presence  of  mercury  in  solutions  of  alkaline  chlorides. 

It  is  always  easy  to  prove  that  the  mercury  exists  in  them  in  the 
state  of  bichloride  ;  it  is  sufficient  for  this  purpose  to  evaporate  the 
solution,  and  to  treat  the  saline  residue  with  alcohol :  this  solvent 
takes  up  a  salt  which  is  not  bicyanide,  but  bichloride  of  mercury. 

VIII.  Pernitrate  of  Mercury. — Like  all  the  other  salts  of  binoxide 
of  mercury,  this  is  converted  into  sublimate  by  the  alkaline  chlorides ; 
this  is  proved  incontestably  by  the  fact,  that  no  trace  of  subnitrate  of 
mercury  is  obtained  by  pouring  pernitrate  of  mercury  into  a  boiling 
solution  of  chloride  of  sodium,  which  would  inevitably  occur  if  this 
curious  reaction  did  not  take  place.  Moreover,  when  the  mixed  solu- 
tion was  treated  with  pure  sulphuric  aether,  it  exhibited  the  reactions 
of  chlorine  and  the  bisalts  of  mercury.  Then  as  pernitrate  of  mer- 
cury is  instantly  decomposed  by  aether,  it  follows  that  the  reactions 
mentioned  certainly  belong  to  corrosive  sublimate. 

IX.  Turbith  Mineral. — This  salt  is  powerfully  attacked  by  the  al- 
kaline chlorides,  as  will  appear  by  the  following  experiments. 

1st  Experiment. — At  the  temperature  of  the  air,  sublimate  pro- 
duced 11  "2  parts. 

2nd  Experiment. — By  the  heat  of  the  stove,  sublimate  produced 
22-8  parts. 

X.  Pertartrate  of  Mercury. — This  salt  is  much  more  soluble  in 
water  than  the  prototartrate,  and  yet  the  proportion  of  sublimate 
which  it  produces  in  solutions  of  the  alkaline  chlorides  is  truly  sur- 
prising. This  reaction  affords  one  of  the  best  examples  which  can 
be  cited  in  favour  of  the  difference  which  exists  between  the  modes  of 
action  of  the  alkaline  chlorides  with  the  two  classes  of  mercurial  salts. 

1st  Experiment. — At  the  temperature  of  the  air,  sublimate  pro- 
duced 31*2  parts. 

2nd  Experiment. — By  the  heat  of  the  stove,  sublimate  produced 
36'2  parts. — Ann.  de  Chim.  et  de  Physique,  Juin  1842. 


Meteorological  Observations.  495 

ON  A  NEW  MODE  OF  FORMING  AMMONIA.     BY  M.  REIZET. 

The  researches  of  M.  Kuhlmann  have  shown  that  under  the  in- 
fluence of  spongy  platina,  nitric  oxide  mixed  with  excess  of  hydrogen 
produced  ammonia.  On  repeating  the  experiments  of  M.  Kuhlmann, 
M.  Reizet  substituted  several  metallic  oxides  for  spongy  platina. 
The  results  which  he  obtained  are  very  interesting,  and  throw  great 
light  on  the  obscure  cause  of  catalytic  action  *.  M.  Reizet  states,  that 
with  an  apparatus,  consisting  of  two  bottles,  each  of  the  capacity  of 
about  60  cubic  inches,  for  evolving  hydrogen  gas  and  nitric  oxide, 
and  1 45  grains  of  sesquioxide  of  iron,  heated  in  one  end  of  an  ana- 
lysis tube,  he  obtained  sufficient  ammonia  to  completely  saturate 
360  grains  of  commercial  hydrochloric  acid. — Ibid. 


METEOROLOGICAL  OBSERVATIONS  FOR  OCTOBER  1842. 

Chiswick. — October  1.  Clear  and  fine.  2.  Foggy  :  fine.  3.  Foggy :  overcast. 
4.  Very  fine.  5.  Cloudless  and  very  fine.  6—8.  Cloudy  and  fine.  9.  Light 
haze:  cloudy.  10.  Overcast.  11.  Foggy:  clear  and  very  fine.  12.  Cloudy. 
13.  Overcast.  14.  Hazy.  15.  Overcast.  16.  Light  haze  :  very  fine.  17.  Hazy: 
overcast  and  fine.  18.  Very  fine:  heavy  rain  at  night.  19.  Fine.  20.  Clear 
and  frosty  :  fine  :  frosty  at  night.  21.  Sharp  frost :  fine :  frosty.  22.  Densely 
overcast :  heavy  rain.  23.  Rain  :  heavy  showers.  24.  Boisterous :  clear  and 
fine  at  night.  25.  Rain :  stormy  at  night.  26.  Very  clear.  27,  28.  Cloudy  and 
fine.  29.  Frosty :  cloudy  and  fine  :  clear  and  frosty  at  night.  30.  Frosty :  clear 
and  fine.  31.  Overcast :  clear  at  night. — Mean  temperature  of  the  month  5°#94 
below  the  average. 

Boston. — Oct.  1.  Cloudy:  rain  early  a.m.  2.  Cloudy.  3.  Cloudy :  rain  a.m. 
4.  Cloudy.  5—8.  Fine.  9,  10.  Cloudy.  11.  Fine.  12,  13.  Cloudy.  14. 
Fine.  15—17.  Cloudy.  18.  Cloudy:  rain  p.m.  19.  Stormy.  20,21.  Fine. 
22.  Stormy :  rain  a.m.  23.  Cloudy.  24.  Windy :  rain  a.m.  25.  Cloudy :  rain 
p.m.    26—31.  Fine. 

Sandwich  Manse,  Orkney. — Oct.  1 /Showers  :  cloudy.  2.  Showers.  3.  Cloudy. 
4.  Showers.  5.  Clear  :  cloudy.  6.  Showers :  rain.  7.  Damp :  cloudy.  8— 
13.  Cloudy.  14,15.  Drizzle:  cloudy.  16.  Cloudy.  17.  Cloudy:  showers. 
18.  Rain  :  sleet.  19.  Hail-showers  :  sleet.  20.  Snow:  hail.  21.  Sleet-showers: 
cloudy.  22.  Rain.  23.  Showers.  24.  Snow :  aurora.  25.  Rain :  aurora. 
26.  Rain :  showers.     27 — 29.  Showers.     30,  31.  Damp. 

Applegarth  Manse,  Dumfries-shire. — Oct.  1 — 3.  Fair  and  fine.  4.  Frost: 
fair  and  clear.  5 — 8.  Fair  and  fine.  9,  10.  Fair  and  fine,  but  cloudy.  11.  Fair 
and  fine  :  clear.  12.  Fair  and  fine.  13.  Fair  and  fine:  frost  a.m.  14.  Fair 
and  fine,  but  cloudy.  15.  Fair  and  fine.  16.  Fair  and  fine :  cloudy.  17. 
Cloudy,  but  fair.  18.  Shower.  19.  Shower  of  snow.  20,21.  Fair  and  clear. 
22,  23.  Heavy  showers  all  day.  24.  Fair  and  clear.  25.  Heavy  fall  of  snow. 
26.  Snow  a.m.  :  melting  p.m.  27.  Fair  and  clear.  28.  Fair  and  clear :  snow 
gone.     29,30.  Fair  and  clear :  frost.     31.  Fair  and  clear :  no  frost. 

Sun  shone  out  28  days.      Rain  fell  4  days.     Frost  4  days.     Snow  3  days. 

Wind  North  3  days.  North-east  1  day.  East-south-east  1  day.  South-east 
2  days.  South-south-east  1  day.  South  1  day.  South-west  4  days.  West- 
south-west  4  days.  West  3  days.  West-north-west  6  days.  North-west  3  days. 
North-north-west  2  days. 

Calm  12  days.  Moderate  5  days.  Brisk  9  days.  Strong  breeze  4  days. 
Boisterous  1  day. 

Mean  temperature  of  the  month 44°*45 

Mean  temperature  of  October  1841    45  '75 

Mean  temperature  of  spring-water 49  -60 

*  On  this  subject  see  Professor  Grove's  paper  in  the  present  Number. 


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THE 
LONDON,  EDINBURGH  and  DUBLIN 

PHILOSOPHICAL   MAGAZINE 

AND 

JOURNAL  OF  SCIENCE. 

SUPPLEMENT  to  VOL.  XXI.  THIRD  SERIES. 


LXXXV.  On  the  Currents  produced  by  the  Actuation  or  In- 
duction of  instantaneous  Electric  Currents.  By  Professor 
Stefano  Marianini*. 

Currents  produced  by  the  Leyden-electrical  Induction. 
I.  rT,HE  facility  with  which,  by  means  of  the  instruments 
described  in  the  preceding  memoir f,  the  presence  of 
an  instantaneous  electric  current  in  a  metallic  wire  is  detected, 
encouraged  me  to  seek  indications  also  of  the  currents  which 
are  derived  from  actuation  or  induction. 

I  had  surrounded  a  little  cylinder  of  iron  with  two  copper 
wires  covered  with  silk,  which  formed  two  parallel  coils,  and 
having  placed  the  cylinder  upon  the  cap  of  a  needle,  I  made 
use  of  this  apparatus  as  a  re-electrometer,  the  delicacy  of 
which  varied  as  I  made  the  currents  pass  through  one  only 
of  the  said  coils,  or  through  both  at  the  same  time,  or  joined 
them  so  that  the  current  had  to  pass  through  one  first,  and 
then  through  the  other;  with  these  two  parallel  coils  I  made 
my  first  attempt  on  the  Leyden-electrical  induction.  Having 
however  taken  that  re-electrometric  cylinder  from  the  cap  of 
the  needle,  I  connected  one  of  the  wires  which  surrounded  it 
with  the  ends  of  the  coil  of  a  re-electrometer,  and  the  Leyden 
jar  being  discharged  upon  the  other  wire,  connecting  its  ex- 
tremities with  the  two  coatings,  I  have  seen  the  needle  of  the 
instrument  deviate  a  similar  number  of  degrees. 

*  Translated  from  Memorie  di  Fisica  Sperimentale  scritte  dal  Professore 
Stefano  Marianini  dopo  it  1836.  Anno  Primo,  1837.  Modena,  1838. 
It  was  from  the  Anno  Sccundo,  1838,  of  this  work  that  the  memoir  by 
the  author  inserted  in  Phil.  Mag.  S.  3.  vol.  xviii.  p.  193  was  translated. 
Prof.  Henry's  researches  on  the  induced  currents  of  common  electricity, 
to  which  the  memoir  now  given  relates,  will  be  found  in  Phil.  Mag.  S.  3. 
vol.  xvi.  p.  551.  The  experiments  of  these  philosophers  were  we  believe 
quite  independent,  and  must  have  been  nearly  contemporaneous ;  but  the 
priority  is  probably  due  to  the  Italian. — Edit. 

[f  The  preceding  memoir  here  referred  to  relates  to  an  instrument  for 
measuring  the  force  both  of  instantaneous  and  non-instantaneous  electric 
currents. — Edit.] 

Phil.  Mag.  S.  3.  No.  141 ,  §uppl.  Vol.  21.  2  L 


^*  \ 


498       Prof.  Marianini  on  the  Currents  produced  by  the 

I  suspected  that  the  deviations  obtained  in  this  and  other 
similar  experiments  might  proceed,  not  from  induction  occa- 
sioned immediately  by  the  instantaneous  current  of  the  jar, 
but  from  magneto-electric  induction,  produced  by  the  tem- 
porary magnetization  of  the  iron  cylinder  surrounded  by  the 
two  coils.  However,  the  cylinder  being  taken  away,  and  a  small 
glass  rod  substituted,  the  same  phoenomenon  took  place. 

II.  As  I  made  use  of  a  jar  highly  charged  and  the  wires 
presented  some  metallic  points  uncovered,  it  was  probable  that 
part  of  the  current  might  make  itself  a  passage  from  one  wire 
to  the  other,  and  that  the  effects  observed  might  proceed  from 
a  real  current  transferred  into  the  wire  of  the  re-electrometer, 
and  not  from  a  movement  of  the  electricity  of  the  wire  itself 
excited  by  the  current  which  was  mafle  to  pass  near  it. 

A  coil  of  large  uncovered  copper  wire  was  enveloped  in 
four  layers  of  silk;  I  then  inclosed  it  in  sixty  coils  of  fine  cop- 
per wire  covered  with  silk;  with  this  apparatus  I  made  many 
trials,  and  I  observed, — 1st,  that  with  the  small  jar  (having 
little  more  than  half  a  square  decimeter  of  coating)  the  needle 
always  deviated  from  the  part,  whence  it  also  deviated  when 
I  discharged  the  jar  itself,  and  in  the  same  manner  upon  the 
wire  of  the  re-electrometer,  as  much  as  when  I  discharged  it 
upon  the  coil  of  uncovered  copper  wire  (keeping  the  fine  wire 
in  communication  with  that  of  the  re- electrometer),  as  when 
I  put  the  coil  of  uncovered  copper  wire  in  communication  with 
this,  and  discharged  the  jar  upon  the  fine  wire ;  2nd,  that  with 
the  large  jars  (nineteen  square  decimeters  of  coating),  if  they 
were  highly  charged,  the  needle  deviated  in  the  same  manner 
as  when  they  were  discharged  upon  the  re-electrometric  wire ; 
but  if  they  were  slightly  charged  the  deviation  was  different. 

III.  I  suspected  that  the  copper  coil  might  exhibit  induc- 
tion in  proportion  as  it  was  itself  magnetized,  and  that  thence 
the  electricity  might  act  instantaneously,  as  a  magnet  does 
when  introduced  into  a  coil  [or  helix].  I  wished  then  to 
prove  whether  the  copper  might  be  magnetized  by  the  dis- 
charged electricities. 

Having  covered  a  copper  cylinder  with  silk  I  inclosed  it  in  a 
coil,  as  I  was  accustomed  to  do  with  the  iron  cylinders.  Having 
then  placed  it  upon  a  magnetized  needle,  I  caused  some  slight 
discharges  of  Leyden  jars  to  pass  through  the  coil  itself,  both 
"weak  and  strong ;  but  I  never  had  the  smallest  indication  of 
magnetism  in  the  copper. 

IV.  Having  taken  the  said  copper  cylinder  from  the  needle, 
I  attached  to  its  extremities  two  metallic  wires,  and  these  I 
connected  with  the  ends  of  the  wire  of  a  re-electrometer ;  then 
discharging  the  Leyden  jar  by  means  of  the  coil  which  sur-. 


Induction  of  instantaneous  Electric  Currents.         499 

rounded  the  cylinder,  the  re-electrometric  deviations  were  no 
longer  wanting. 

I  suspended  the  connexion  between  the  little  copper  cylin- 
der and  the  wire  of  the  instrument,  and  having  connected  it 
instead  with  the  ends  of  the  coil  which  surrounded  it,  and  then 
discharged  the  Leyden  jars  upon  the  cylinder  itself,  the  usual 
deviations  no  longer  failed.  Are  not  these  phaenomena  de- 
pendent uponLeyden-electrical  actuation  ?  As  I  invariably  saw 
that,  when  I  made  the  discharges  pass  through  two  points  of 
the  coil  itself,  there  were  very  nearly  the  same  deviations ;  and 
in  the  other  case  (namely,  when  the  copper  cylinder  was  con- 
nected with  the  wire  of  the  re-electrometer)  there  was  exactly 
the  same  effect  when  I  discharged  the  jar  connecting  it  with 
the  two  ends  of  the  cylinder,  I  doubted  whether,  instead  of 
inductions,  I  might  not  hitherto  have  seen  only  the  effects  of 
a  division  and  subdivision  of  the  discharge. 

.  V.  It  appeared  to  me  that  I  had  taken  the  most  scrupulous 
precautions  that  there  might  be  no  metallic  contact  between 
the  actuating  wire  and  that  to  be  actuated ;  but  might  it  not 
be  that  even  through  the  silk  the  electricity  might  make  itself 
a  passage  ?  The  doubt  was  so  much  the  more  reasonable,  as 
from  the  experiments  related  in  the  preceding  memoir  I  had 
learned  that  the  currents  of  the  Leyden  jars  might  divide 
themselves  between  good  and  bad  conductors ;  I  sought  there- 
fore to  clear  up  this  doubt  by  the  following  experiments. 

I  put  the  ends  of  the  wire  itself  in  metallic  communication 
by  means  of  a  band  of  lead  two  centimeters  broad  and  eight 
decimeters  long;  I  covered  one  part  with  a  small  piece  of  very 
dry  wool ;  then  upon  this  wool  and  above  the  band  itself  I  ex- 
tended for  the  space  of  a  decimeter,  another  band  of  the  same 
metal,  which  rose  at  a  right  angle  from  both  parts,  for  the 
space  of  four  centimeters.  Having  many  times  discharged 
the  Leyden  jar,  now  in  one  manner,  now  in  the  other,  putting 
the  coatings  in  contact  with  the  extremities  of  the  second 
band,  deviations  of  two,  three,  and  even  six  degrees  in  the 
needle  of  the  re-electrometer  were  always  obtained. 

I  repeated  the  same  experiments  after  having  put  four  small 
pieces  of  wool  between  the  band  of  lead  adjoining  the  ends  of 
the  re-electrometric  coil  and  that  upon  which  the  jars  were 
discharged,  and  the  results  were  pretty  nearly  the  same.        * 

The  deviations  were  somewhat  smaller  (though  they  never 
failed)  when,  besides  the  said  pieces  of  wool,  I  also  placed 
between  the  two  metallic  bands  a  large  cake  of  sealing-wax 
having  a  strongly  insulating  power,  and  six  good  millimeters 
in  size.  And  as  in  these  experiments  I  made  use  of  a  small 
jar  highly  charged,  and  the  spark  passed  thence  to  a  great 

2L2 


500       Prof.  Marianini  on  the  Currents  produced  by  the 

distance,  so  to  remove  my  doubt  that  some  part  of  the  dis- 
charge might  fall  upon  the  neighbouring  bodies  instead  of 
the  extremity  of  the  metallic  band  upon  which  I  intended  the 
spark  to  pass,  I  attached  two  long  copper  wires  to  the  ex- 
tremities of  the  said  band,  and  I  went  to  some  meters  distance 
to  discharge  the  jar ;  but  the  effects  upon  the  re-electrometer 
were  not  different  from  those  already  observed. 

If  these  experiments  do  not  serve  to  show  that  the  current 
of  the  Leyden  jar  passing  through  a  metal  causes  in  a  neigh- 
bouring metal  an  electric  current  by  induction,  they  would 
yet  prove  a  very  singular  and  unexpected  property  of  the 
discharge  of  the  Leyden  jar  ;  that  I  mean  of  dispersing  itself 
in  part  in  the  worst  conductors,  even  after  having  begun  to 
traverse  the  best,  since  it  must  be  said  that  the  electric  fluid 
descending  by  the  vertical  band  scarcely  reaches  the  point 
where  this  touches  the  wool  or  the  sealing-wax,  when  a  part 
of  it  quickly  passes  through  the  wool  itself,  and  finding  the 
band  of  lead  underneath,  a  fraction  of  this  part  of  the  cur- 
rent passes  into  the  band  itself  which  is  under  the  wool,  and 
reaches  the  external  coating  of  the  jar  by  the  shortest  way ; 
whilst  the  other  fraction  makes  a  much  greater  turn  to  traverse 
the  coil  around  the  re-electrometric  iron,  and  at  length  reach- 
ing the  wool  from  the  opposite  part,  and  there  passing  through 
the  confining  stratum,  rejoins  the  other  part  of  the  larger  band 
communicating  with  the  external  coating  of  the  jar.  That  such 
a  dispersion  and  division  of  discharge  does  not  take  place, 
seems  proved  by  the  experiments  which  I  shall  now  describe. 

VI.  I  made  the  experiments  of  the  preceding  section,  but 
instead  of  laying  the  plate  upon  which  the  jar  was  discharged 
upon  the  confining  portion  for  the  space  of  two  decimeters, 
I  caused  it  to  touch  it  only  at  a  few  points,  bending  it  up- 
wards at  both  sides ;  and  I  observed  that  if  that  part  of  the 
plate  parallel  to  the  under  one  was  distant  from  the  latter  only 
a  few  centimeters,  the  effects  upon  the  re-electrometer  were 
still  visible ;  but  when  the  distance  was  two  decimeters,  there 
were  no  longer  any  deviations  in  the  re-electrometer. 

Having  again  laid  the  said  plate  upon  the  confining  stratum, 
I  cut  in  two  the  leaden  band  which  communicated  with  the 
ends  of  the  re-electrometer,  and  I  placed  near,  between  them, 
the  sections,  without  their  touching ;  and  this  was  done,  be- 
cause, if  in  discharging  the  Leyden  jar  a  part  of  the  current 
were  carried  upon  this  plate,  crossing  the  confining  part,  all 
this  portion  must  pass  through  the  coil  of  the  re-electrometer, 
and  thence  produce  much  greater  deviations  than  when  the 
band  offered  a  continued  conductor.  But,  on  the  contrary, 
the  effects  in  this  case  were  nothing ;  consequently,  in  these 


Induction  of  instantaneous  Electric  Currents.         501 

trials,  either  the  suspected  dispersion  does  not  take  place,  or 
if  it  does,  the  movements  of  the  magnetized  needle  do  not 
proceed  from  it. 

VII.  Instead  of  placing  the  plate,  which  we  will  call  the 
actuating  plate,  parallel  to,  and  above  the  other  which  closes 
the  re-electrometric  circuit,  and  which  we  will  call  the  actuated 
one,  I  placed  it  parallel  to  it  laterally,  and  at  the  horizontal 
distance  of  two  centimeters.  The  currents  produced  by  Ley- 
den-electrical  induction  were  somewhat  weaker ;  but  neverthe- 
less sufficiently  great  to  be  seen,  and  measured. 

VIII.  Having  replaced  the  actuating  plate*  above  the 
other,  and  turned  it  somewhat  in  the  horizontal  plane  round 
its  central  point,  so  that  it  might  form  an  angle  with  the  under 
one,  the  induced  current  was  weaker,  and  still  more  so  when 
the  angle  was  greater.  If  the  angle  was  of  60  degrees,  the  de- 
viation caused  in  the  instrument  by  the  induced  current  was 
scarcely  perceptible.  And  these  experiments  also  prove,  that 
the  deviations  do  not  proceed  from  a  current  transferred  by 
dispersion,  but  rather  from  true  Leyden-electrical  induction. 

IX.  Having  joined  the  ends  of  the  re-electrometric  coil  by 
means  of  a  fine  copper  wire,  silvered,  and  then  covered  as 
usual  with  the  little  pieces  of  wool,  and  with  the  sealing-wax 
upon  which  was  the  usual  plate  of  lead  or  copper,  or  zinc, 
upon  which  the  jar  was  discharged,  the  induction  took  place 
as  usual.  It  took  place  equally  when  the  ends  of  the  coil  were 
connected  with  one  of  the  said  plates,  and  the  jar  was  dis- 
charged upon  the  metallic  wire  duly  placed  upon  the  cake  of 
sealing-wax. 

X.  I  placed  upon  the  said  cake  two  insulating  supports  of 
glass,  covered  with  sealing-wax,  five  centimeters  high,  and 
upon  them  the  usual  metallic  plate,  duly  placed  under  one 
part  of  the  re-electrometric  wire.  I  then  discharged  the  Ley- 
den  jar  from  one  end  to  the  other  of  the  plate  itself,  and  I  had 
the  deviation  by  actuation  which  at  that  distance  I  usually 
obtained. 

Having  inclosed  in  many  folds  of  silk  ribbin  all  but  the 
extremities  of  the  actuating  plate  upon  which  I  wished  to  dis- 
charge the  jar,  and  which  I  held  in  my  hand  parallel  to  the 
actuated  plate,  and  carried  to  the  height  of  six,  ten,  and  even 
fifteen  centimeters,  the  signs  of  electric  induction  never  failed. 

XI.  The  position  and  direction  of  the  jar  when  discharging 

*  For  the  sake  of  brevity,  I  call  a  band  or  plate  actuating  through  which 
the  electricity  passes,  or  ought  to  pass,  its  extremities  being  connected 
with  the  coatings  of  a  Leyden  jar  or  of  a  Franklinian  square  [see  note,  p. 
509.];  and  I  call  a  plate  actuated,  in  which  (being  near  the  former)  arises, 
or  may  arise,  an  induced  electric  induction. 


502         Prof.  Marianini  on  the  Currents  produced  by  the 

it,  never  produced  any  difference  in  the  results  ;  certainly  the 
effects  were  less  when  the  distance  between  the  two  points  of 
the  plate  upon  which  the  jar  was  discharged  was  less  :  and  if 
such  distance  was  sufficiently  small,  as  for  example,  one  cen- 
timeter, there  was  no  indication  of  an  induced  current,  al- 
though the  actuating  plate  might  only  be  separated  from  the 
actuated  by  a  very  fine  little  portion  of  silk  or  wool. 

XII.  A  band  of  lead,  one  meter  long  and  two  centimeters 
broad,  was  for  the  space  of  six  decimeters  inclosed  in  silk  rib- 
bin,  leaving  two  decimeters  of  it  bare  at  each  extremity.  I 
applied  over  this,  but  only  for  the  space  of  five  centimeters  in 
the  middle,  a  longer  band  of  the  same  metal,  and  in  order  that 
they  might  be  in  better  apposition  to  each  other,  I  surrounded 
them  both  with  silk  thread  in  an  open  coil  for  all  the  said 
space.  The  uncovered  band  was  then  folded  back,  half  a  de- 
cimeter of  the  covered  band  remaining  on  each  side  to  pre- 
vent the  danger  of  any  metallic  contact  between  the  two 
bands.  I  connected  the  extremities  of  the  uncovered  band 
with  the  metallic  wire  of  a  re-electrometer,  and  then  dis- 
charged the  Leyden  jars,  putting  the  two  coatings  in  contact 
with  the  uncovered  extremities  of  the  band  covered  with  silk 
ribbin,  as  above  mentioned.  During  these  experiments  the 
currents  produced  by  the  Leyden-electrical  induction  caused 
much  greater  deviations  in  the  magnetized  needle  than  those 
which  occurred  in  the  experiments  hitherto  described,  in  which 
I  caused  the  actuating  current  to  act  upon  a  part  of  the  ac- 
tuated band  which  was  not  longer  than  two  decimeters. 

The  uncovered  extremities  of  the  leaden  band  partially  co- 
vered with  silk,  having  been  connected  with  the  wire  of  the 
re-electrometer,  and  the  Leyden  jar  being  discharged  upon  the 
extremities  of  the  other  band,  the  effects,  in  similar  circum- 
stances, were  perfectly  equal. 

Again,  with  the  weakest  discharges  and  even  with  the  first 
two  or  three  residual  charges,  manifest  indications  of  induc- 
tion followed  on  experimenting  with  similar  bands  of  lead, 
placed  adjacent,  in  the  manner  I  have  mentioned. 

XIII.  Seeing  that  I  could  obtain  induced  currents  by  means 
of  the  weakest  actuating  currents,  also  by  means  of  currents 
which  when  made  to  act  directly  upon  the  re-electrometer 
produced  deviations  less  than  those  which  followed  from  the 
actuated  currents  produced  by  strong  discharges  of  Leyden 
jars,  I  thought  it  would  not  be  time  lost  to  attempt  to  obtain 
the  inductions  of  the  said  induced  currents. 

A  band  covered  with  silk  for  the  space  of  seven  decimeters, 
with  the  extremities  bare,  had  attached  to  all  that  part  of  it  co- 
vered with  silk,  with  the  exception  of  two  centimeters  on  each 


Induction  of  instantaneous  Electric  Currents-  503 

side,  a  second  uncovered  band ;  this  remained  on  one  side  free 
for  one  decimeter ;  and  on  the  other  for  nine,  the  two  ends  being 
connected  together.  Seven  decimeters  of  this  second  band 
(in  the  space  not  attached  to  the  first)  were  covered  with  silk, 
and  to  all  this  part,  except  two  decimeters,  was  attached  a 
third  uncovered  band,  having  also  a  space  of  one  decimeter 
free  on  one  side,  and  nine  decimeters  free  on  the  other. 
Things  being  thus  disposed,  the  ends  of  the  first  band  were 
connected  with  those  of  the  coil  of  the  re-electrometer,  and 
the  ends  of  the  third  band  were  destined  to  be  connected  with 
the  two  coatings  of  the  Leyden  jar. 

The  trial  being  made,  the  deviations  of  the  needle  of  the  re- 
electrometer  never  failed.  The  usual  small  Leyden  jar  being 
charged  as  highly  as  possible,  that  is  to  about  80  degrees  of 
the  quadrant  electrometer,  there  was  a  deviation  of  almost 
seven  degrees.  When  charged  to  twenty  degrees,  there  was 
a  deviation  of  one  degree  and  a  half;  and  also  with  weak 
charges,  and  on  many  occasions  with  mere  residual  charges, 
I  obtained  visible  deviations.  Then  the  instantaneous  current 
which  passed  into  the  third  band  of  lead  caused  an  induced 
current  in  the  second,  which  formed  as  it  were  a  large  closed 
ring,  and  this  current  in  its  turn  caused  a  second  Leyden- 
electrical  induction  in  the  first  band,  which  formed  as  it  were 
a  second  large  ring  or  closed  circuit,  being  joined,  as  I  have 
stated,  to  the  re-electrometric  coil. 

I  closed  also  the  circuit  formed  by  this  third  band,  by  con- 
necting the  ends  of  it,  and  covered  a  free  space  of  seven  de- 
cimeters with  silk,  and  attached  to  it  a  fourth  uncovered  band 
in  the  manner  now  described ;  the  Leyden  jar  being  dis- 
charged upon  this,  there  were  unequivocal  signs  of  an  in- 
duction which  we  will  call  of  the  third  order,  and  I  thus  ob- 
tained also  the  induced  currents  of  the  fourth  and  fifth  orders, 
by  adding  another  ring  similar  to  those  described,  and  then 
another  still. 

XIV.  After  the  result  here  stated,  there  appeared  to  me 
no  longer  any  doubt  that  the  instantaneous  currents  of  the 
confining  armatures  cause  currents  by  true  induction  or  ac- 
tuation in  the  conductors  near  which  they  pass;  and  I  ad- 
dressed myself  to  study  the  properties  of  this  action.  I  wished 
first  to  see  whether  the  induction  would  take  place  even  if 
there  should  be  some  metallic  stratum  as  well  as  the  confining 
strata  between  the  actuating  and  actuated  conductors. 

Between  two  bands  of  lead,  both  covered  with  silk,  I  placed 
another,  with  care,  in  order  that  there  might  be  no  metallic 
contact  between  the  bands.  Having  connected  one  of  the 
covered  bands  with  the  wire  of  the  re-electrometer,  and  di6- 


504         Prof.  Marianini  on  the  Currents  produced  by  the 

charged  the  Ley  den  jar  upon  the  other  similarly  covered,  the 
needle  deviated,  as  when  there  was  no  naked  band  between 
the  actuating  and  the  actuated  plates. 

But  if  the  two  ends  of  the  metallic  band  between  the  ac- 
tuating and  the  actuated  plates  were  connected,  then  the 
Leyden  jar  being  discharged  as  above,  thei'e  was  no  deviation 
in  the  re-electrometer,  or  it  was  very  small,  and  only  took 
place  when  the  jar  was  considerably  charged;  which  appears 
to  me  to  prove,  that  when  the  actuating  current  operates  upon 
a  closed  metallic  circuit,  it  induces  in  it  a  contrary  current, 
which  either  wholly  or  in  part  destroys  the  effect  of  the  ac- 
tuating current  upon  the  second  actuated  band. 

I  connected  the  ends  of  the  middle  band  with  the  re-elec- 
trometer, and  now  connected  the  ends  of  the  third  band  with 
them,  now  employed  them  unconnected.  In  the  first  case,  the 
jar  being  discharged  upon  the  first  band,  the  deviations  were 
somewhat  small,  and  in  the  second  evidently  greater.  There 
was  not  so  much  difference  in  the  two  cases  as  in  the  prece- 
ding experiment,  in  spite  of  the  small  interval  between  the  ac- 
tuating band  and  the  immediately  actuated  one. 

XV.  Two  silvered  copper  wires  were  placed  parallel  to 
each  other,  each  by  means  of  two  pegs  of  wood  covered  with 
sealing-wax,  at  one  meter  distant  from  each  other,  and  move- 
able, so  as  to  allow  the  distance  between  the  wires  to  be 
varied,  while  they  still  remained  parallel.  Having  connected 
one  of  these  with  the  ends  of  the  wire  of  a  re-electrometer, 
and  discharged  the  Leyden  jar  upon  the  other,  I  saw  that 
the  induction  visibly  took  place,  even  when  the  distance  be- 
tween the  actuating  and  actuated  wires  was  seven  centime- 
ters. 

I  have  already  observed  in  §  XL,  that  when  the  actuation 
only  took  place  on  a  small  space  of  the  actuated  conductor, 
the  effect  was  less.  Now,  applying  the  ends  of  the  re- electro- 
metric  wire  to  two  points  more  or  less  distant  from  each  other, 
I  have  observed  that  the  signs  of  an  induced  current  began 
to  appear  when  the  extent  of  wire  subject  to  actuation  was 
about  a  centimeter  and  a  half,  and  the  distance  from  the  ac- 
tuating wire  two  millimeters.  When  the  actuated  wire  was 
three  centimeters  long  a  degree  of  deviation  was  obtained, 
and  this  increased  to  ten  degrees  when  the  extent  of  actuated 
wire  was  six  or  seven  decimeters.  It  did  not  increase  on  the 
wire  being  considerably  lengthened,  which  I  tried  to  the  ex- 
tent of  a  meter.  I  have  observed  the  same  on  varying  the 
length  of  the  actuating  wire. 

XVI.  I  connected  the  ends  of  a  perfect  Nobili's  multiplier 
with  those  of  the  actuated  metallic  wire,  and  discharged  the 


Induction  of  instantaneous  Electric  Currents.         505 

Leyden  jar  upon  the  actuating  wire  under  the  most  favour- 
able circumstances  for  obtaining  the  induced  current;  but  the 
galvanometer  did  not  make  the  smallest  movement ;  nor  was 
the  result  different  when  experimenting  with  the  bands  of  lead 
instead  of  the  copper  wires ;  and  this  proves  that  such  ac- 
tuated currents  are  instantaneous,  like  the  actuating. 

XVII.  On  obliging  the  actuating  current  to  pass  through 
a  metallic  wire  several  hundred  meters  in  length,  the  induced 
current  was  excited ;  nor  did  I  perceive  any  different  effect 
when  it  did  not  pass  through  that  long  wire.  The  same  re- 
sult also  occurred  when  I  forced  the  induced  current  to  pass 
through  the  long  wire  before  reaching  the  re-electrometer. 

The  induction  did  not  fail  either,  when,  instead  of  one  end 
of  the  actuated  wire  being  in  metallic  contact  with  one  end 
of  the  coil  of  the  re-electrometer,  both  were  immersed  in 
water,  and  distant  from  each  other  more  than  a  decimeter ; 
nor  was  the  result  different  when  the  actuating  current  was 
made  to  pass  through  a  stratum  of  water  more  or  less  thick. 

The  inductions  of  the  second  and  third  orders  also,  did 
not  fail  when  made  to  pass  through  a  long  metallic  wire  or  a 
stratum  of  water,  although  under  such  circumstances  they 
appeared  much  weaker. 

XVIII.  Making  use  of  a  small  iron  cylinder  surrounded 
by  two  parallel  coils,  similar  to  that  mentioned  in  §  I.,  I  con- 
nected the  two  ends  of  one  of  them,  and  having  discharged 
upon  the  other  the  small  Leyden  jar  charged  to  fifteen  de- 
grees, no  movement  of  the  magnetized  needle  ensued ;  and  the 
reason  appears  to  me  to  be  that  the  current  induced  in  the 
circuit  so  formed  was  contrary,  and  nearly  equal  in  magneti- 
zing force  to  the  immediate  current. 

I  have  also  constantly  observed,  that  the  somewhat  weaker 
currents  of  the  first  two  or  three  residual  charges  were 
indicated  by  one  or  two  degrees  of  deviation ;  and  this,  as 
it  appears  to  me,  arises  from  the  weakest  current  not  being 
sufficient  to  cause  a  sensible  induced  current  in  the  wire 
circuit  already  mentioned. 

Thus  I  have  seen  that  a  stronger  charge,  for  example  of 
forty  or  fifty  degrees,  was  indicated  by  several  degrees  of  de- 
viation ;  never,  however,  so  many  as  were  observed  when  the 
other  wire  was  unconnected :  and  this  shows  that  when  the 
wire  was  joined  the  immediate  current  prevailed  over  the  in- 
duced. 

XIX.  The  phenomena  of  induction  of  which  I  have  hitherto 
spoken,  presented  no  anomalies  to  me ;  but  this  was  not  the 
case  with  respect  to  the  direction  of  the  induced  current.  In 
most  of  the  experiments  on  this  subject  I  made  use  of  three 


506        Prof.  Marianini  on  the  Currents  'produced  by  the 

small  Leyden  jars  not  having  more  than  a  square  decimeter 
of  exterior  coating,  and  with  each  of  these  I  observed  that  the 
re-electrometric  deviations  indicated  that  the  induced  currents 
were  directly  contrary  to  the  actuating.  If,  for  example,  the 
discharge  of  the  jar  in  the  direction  of  the  band,  or  of  the  ac- 
tuating wire  parallel  to  the  actuated,  proceeded  from  right  to 
left ;  in  the  band,  or  in  the  neighbouring  actuated  wire,  the 
induced  current  passed  from  left  to  right:  and,  seeing  in  this 
an  analogy  to  the  volta-electric  induction  of  Faraday*,  I  felt 
more  and  more  persuaded  that  the  phenomena  observed  pro- 
ceeded really  from  Leyden-electrical  induction.  But  I  quickly 
began  to  doubt  it  when  I  applied  myself  to  confirm,  with  the 
large  jars,  the  results  obtained  with  the  small;  for,  on  using 
these,  the  deviations  of  theinstrument  indicated  that  the  induced 
current,  and  that  which  caused  it,  proceeded  in  the  same  di- 
rection in  the  two  parallel  and  neighbouring  conductors. 

I  doubted  whether,  from  the  quantity  of  electricity  being 
different  in  proportion  to  the  tension,  a  different  distance 
might  not  be  required  between  the  actuating  and  actuated 
conductors,  in  order  to  produce  the  direct  current  in  a  given 
manner  in  the  latter  ;  and  whether  in  such  phaenomena  there 
might  not  be  something  analogous  to  the  inversions  of  mag- 
netization observed  by  Savary  in  steel  needles,  placed  at  dif- 
ferent distances  from  the  conductors  through  which  he  made 
the  discharges  of  great  electrical  batteries  to  pass.  But  what- 
ever was  the  distance  between  the  actuating  and  actuated 
conductors,  which  I  have  varied  from  one  millimeter  to  a 
hundred,  the  inductions  of  the  smaller  jars  were  always  di- 
rectly opposite  to  those  of  the  larger. 

I  turned  my  attention  to  the  construction  of  the  little  jars, 
and  I  observed  that  they  had  the  internal  coatings  formed  of 
cuttings  of  tin-foil  and  silvered  paper  ;  I  conjectured  that  the 
difference  of  effects  in  the  large  and  small  jars  might  depend 
on  that  discontinuity  of  the  coating;  and  I  long  held  this 
opinion,  from  having  observed  that  two  large  jars,  having  the 
external  coatings  formed  of  so  many  small  squares  of  tin-foil, 
of  about  one  centimeter  square,  attached  to  the  glass,  so  that 
between  them  might  be  a  band  of  bare  glass,  of  two  or  three 
millimeters  broad,  acted  in  precisely  the  same  manner  as  the 
said  small  jars.  But  finally,  having  had  some  small  jars  pre- 
pared with  internal  and  external  coatings  adhering  to  the 
glass,  as  in  the  large  ones,  I  saw  that  they  produced  the  cur- 
rents by  induction  in  the  same  direction  as  the  large  and  small 
jars  with  discontinuous  coatings  ;  whence  I  was  convinced  that 

[*  See  Faraday'sJExperimental  Researches  in  Electricity  (26.),  or  Phil. 
Mag.,  Second  Series,  vol.  xi.  p.  300. — Edit.] 


Induction  of  instantaneous  Electric  Currents.  507 

the  cause  of  those  different  effects,  although  remote,  depended 
on  the  different  capacity  of  the  jars ;  for  the  large  jars,  with  dis- 
continuous external  coatings,  may  be  considered  as  furnished 
with  small  electric  capacities  only,  as  many  of  these  small  squares 
remain  idle  in  charging  or  discharging  the  jars  themselves. 

Considering,  then,  that  the  least  capacity  of  the  confining 
coatings  involves  as  a  consequence,  that  with  similar  charges, 
that  is,  furnished  with  an  equal  quantity  of  electricity,  the 
spark  must  pass  to  a  greater  distance,  and  thence  find  a  similar 
expenditure  in  the  longer  space  of  air  which  it  must  traverse, 
I  wished  to  see,  if  by  effecting  a  retardation  in  the  discharges 
of  the  large  jars,  there  might  perhaps  be  the  same  direction  of 
the  induced  current  that  was  observed  with  jars  of  less  power. 

I  therefore  caused  the  discharges  of  the  large  jars  to  pass 
through  the  water  in  a  glass  before  reaching  the  actuating 
wire;  and  I  saw  that  in  this  case  these  jars  acted  as  those 
furnished  with  much  less  capacity.  It  is  singular  to  see  how 
the  same  quantity  of  electricity,  put  in  motion  by  the  same 
jar,  induces  a  current,  either  in  one  direction  or  in  that  pre- 
cisely opposite,  according  as  it  is,  or  is  not,  made  to  pass 
through  a  liquid  stratum. 

The  different  velocity,  then,  with  which  the  electricity  dis- 
charges itself  from  the  one  coating  to  the  other,  seems  to  give 
rise  to  the  said  inversions  of  phenomena :  and  in  this  opinion 
I  was  confirmed  by  having  many  times  observed,  when  expe- 
rimenting with  the  bands  of  lead  described  in  §  XII.,  that  a 
jar  of  great  power  (capacitd)  strongly  charged  and  discharged 
upon  the  actuating  band,  caused  the  induction  contrary  to 
that  of  the  little  jars ;  and  with  the  first  residual  charge  there 
was  no  effect,  with  the  second  and  third  an  opposite  one. 

XX.  A  glass  tube  of  about  two  centimeters  in  diameter, 
and  twenty  in  length,  was  filled  with  spring  water,  and  closed 
with  two  corks,  through  the  axis  of  each  of  which  passed  a 
brass  wire  so  far  as  to  touch  the  water ;  both  these  wires  pro- 
jected out  for  the  space  of  some  centimeters,  and  terminated 
in  a  little  globe.  Having  duly  dried  the  exterior  of  the  tube, 
and  surrounded  it  with  a  band  of  lead  two  centimeters  wide, 
which  was  twisted  round  it  three  times  in  the  middle  part  of 
the  tube*  the  ends  of  the  bands  were  put  in  metallic  commu- 
nication with  the  extremities  of  the  re-electrometric  wire. 
Having  discharged  the  Leydeh  jar  so  that  it  must  pass  through 
the  water  of  the  tube,  I  brought  the  external  coating  into 
contact  with  the  little  globe  of  one  of  the  said  wires,  and  the 
internal*  with  the  little  globe  of  the  other,  and  the  needle 
deviated  two  degrees. 

[*  Jrmaltira  externa  in  the  original,  but  obviously  in  error. — Edit.] 


508       Prof.  Marianini  on  the  Currents  produced  by  the 

Saline  water  being  substituted  for  the  spring  water,  a  devia- 
tion of  five  degrees  was  obtained. 

In  order  the  better  to  assure  myself  of  the  insulation,  I 
twisted  round  the  tube  a  band  of  lead  covered  with  silk ;  I 
repeated  the  experiments  several  times,  and  the  results  were 
always  such  as  to  lead  to  a  conclusion  that  it  was  not  neces- 
sary that  the  electricity  should  pass  through  a  metal  to  cause 
the  Leyden-electrical  induction ;  it  being  sufficient  that  it 
should  pass  through  some  conductor,  in  order  that  the  passage 
might  be  accomplished  with  sufficient  celerity. 

XXI.  I  connected  the  liquid  contained  in  the  tube  which 
was  used  in  the  experiments  above  described,  with  the  ends 
of  the  re-electrometric  wire,  and  I  then  discharged  the  Leyden 
jar  upon  the  extremities  of  the  band  which  surrounded  the 
tube  itself.  The  needle  deviated  almost  a  degree.  I  renewed 
the  experiment ;  but  on  repeating  the  same  discharge  in  the 
same  direction  six  times,  I  found  the  needle  deviated  four  de- 
grees. Hence  we  see  that  it  is  not  necessary  that  the  actuated 
conductor  should  be  metallic,  in  order  that  the  Leyden-elec- 
trical induction  should  take  place. 

From  the  experiments  of  this  and  the  preceding  paragraph, 
it  may  be  deduced,  that  the  induction  would  take  place  if 
neither  the  actuating  nor  the  actuated  conductor  were  metal- 
lic ;  which,  I  believe,  I  have  also  verified  by  apposite  experi- 
ments. 

XXII.  Having  interrupted  the  actuating  wire  in  another 
place,  I  connected  one  end  of  it  with  the  external  coating  of  a 
Leyden  jar  not  charged,  and  the  other  with  the  internal*.  I 
afterwards  discharged  a  jar  equal  to  that  in  power  upon  the 
wire  itself.  The  induction  took  place,  and  the  charge  was 
divided  between  the  two  jars,  which  proves  that  it  is  not  ne- 
cessary that  the  identical  fluid  of  one  coating  should  pass  to 
the  other,  to  produce  the  phsenomena  of  Leyden-electrical 
induction. 

XXIII.  Also  the  simple  sparks  drawn  from  the  prime  con- 
ductor may  produce  currents  by  actuation.  Whilst  one  of  the 
wires  described  in  §  XV.  was  connected  with  the  re-electro- 
metric coil,  I  let  pass  some  sparks  upon  one  extremity  of  the 
other,  keeping  the  other  extremity  in  communication  with  the 
ground ;  and  I  observed  some  movement  in  the  magnetized 
needle  at  every  spark  that  appeared. 

Once,  with  fifteen  sparks  directed  upon  the  actuating  wire, 
a  magnetization  in  the  iron  of  the  re-electromeler  was  obtained 
with  the  induced  currents,  which  caused  the  needle  to  deviate 
three  degrees. 

[*  Armatura  externa  in  the  original)  but  obviously  in  error.— Edit.] 


Induction  of  instantaneous  Electric  Currents.        509 

But  reserving  to  myself  to  treat,  on  another  occasion,  of  the 
induced  currents  produced  by  sparks  and  by  other  electric 
currents,  artificial  or  natural,  it  appears  to  me  that  we  may  in 
the  mean  time  conclude, — 

1st.  That  the  instantaneous  current  of  the  Leyden  jar,  or 
of  the  Franklinian  square*  passing  through  a  metallic  cur- 
rent, causes  an  electric  current,  also  instantaneous,  in  another 
metallic  conductor,  near  to  it,  and  forming  a  closed  circuit, — 
a  phenomenon  which  I  call  Ley  den-electrical  induction,  be- 
cause analogous  to  that  called  by  Faraday  volta-electric  in- 
duction. 

2nd.  That  the  same  induced  current  may  cause  in  another 
conductor  a  second  current  of  induction ;  and  this  second, 
again  another,  and  so  on ;  whence  may  be  produced  currents 
of  Leyden-electrical  induction,  of  the  second  and  third  orders, 
&c. 

3rd.  That  the  Leyden-electrical  induction  also  takes  place 
when  the  circuit  through  the  metallic  actuated  conductor  is 
closed  by  a  very  long  metallic  conductor,  or  even  by  a  con- 
ductor not  wholly  metallic. 

4th.  That  such  induction  also  takes  place  when  the  dis- 
charge of  the  Leyden  jar  traverses  a  very  long  metallic  con- 
ductor, and  also  a  non-metallic  conductor ;  nor  does  the 
phenomenon  fail  to  appear,  when  it  is  not  the  identical  fluid 
of  one  coating  which  passes  to  the  other. 

5th.  That  the  induced  current  takes  in  the  actuated  con- 
ductor the  same  direction  which  the  inducing  current  takes 
in  the  actuating  conductor  whenever  the  jar  has  great  electric 
capacity,  and  is  not  too  weakly  charged.  But  the  direction 
is  opposite  when  the  charge  of  the  jar  is  rather  weak,  or  when 
the  electricity  has  to  pass  through  a  bad  conductor,  or  when 
the  jar  is  of  small  electric  capacity. 

6th.  That  the  phenomena  of  induction  may  be  seen, 
although  neither  the  actuating  nor  the  actuated  conductor  is 
metallic. 

7th.  That  finally,  such  inductions  are  not  exclusively  from 
Leyden  jars  and  the  Franklinian  square,  but  are  obtained 
also  with  instantaneous  electric  currents  from  other  sources. 

[*  Quadro  Frankliniano  ;  meaning,  we  presume,  the  pane  of  glass  with 
tin-foil  coating  on  both  sides ;  but  this,  we  believe,  was  the  device,  not  of 
Franklin,  but  of  Smeaton. — Edit.] 


[     510     ] 

LXXXVI.  Proceedings  of  Learned  Societies. 

ROYAL  ASTRONOMICAL  SOCIETY*. 

Extracts  from  the  Report  of  the  Council  to  the  Twenty -second  Annual 
General  Meeting,  held  this  day. 

Feb.  11,  A  MONGST  the  losses  by  death,  the  Council  have  here 
1842.  •£*•  to  notice  one  among  the  Foreign  members,  which  was 
announced  at  the  last  anniversary,  namely,  that  of  Professor  Littrow 
of  Vienna,  who  was  one  of  the  earliest  members  of  this  Society. 
He  contributed  several  papers  which  were  read  at  the  meetings,  and 
which  have  been  printed  in  the  first  four  volumes  of  the  Memoirs, 
exhibiting  a  spirit  of  research  and  inquiry  into  a  variety  of  subjects 
connected  not  only  with  astronomy,  but  also  with  other  hranches  of 
physical  science.  He  was  also  the  author  of  a  valuable  Treatise  on 
Astronomy,  in  three  volumes  octavo,  in  the  German  language,  and 
continued,  till  the  time  of  his  death,  to  conduct  the  affairs  of  the  Im- 
perial Observatory  at  Vienna. 

The  Council  have  also  to  regret  the  loss  of  Mr.  Frend,  lately  one 
of  the  Members  of  the  Council  of  the  Society. 

William  Frend  was  the  son  of  George  Frend,  an  alderman  of 
Canterbury,  in  which  city  he  was  born,  November  22,  1757.  He 
received  his  education  in  his  native  place,  at  the  King's  School ;  and, 
after  staying  some  time  at  St.  Omer,  was  placed  in  a  mercantile 
house  at  Quebec ;  but  the  breaking  out  of  the  disturbances  in  Ame- 
rica destroyed  his  commercial  prospects,  and  he  returned  to  En- 
gland. His  wishes  being  directed  towards  the  Church,  he  was 
placed  at  Christ's  College,  Cambridge,  in  1775,  and  took  the  degree 
of  B.A.,  with  the  honour  of  second  wrangler,  in  1780.  After  taking 
his  degree,  he  almost  immediately  removed  to  Jesus  College,  of  which 
he  was  elected  fellow  and  tutor.  In  1783  he  was  ordained,  and 
afterwards  obtained  the  living  of  Madingley,  near  Cambridge.  In 
1787,  a  change  in  his  religious  opinions  took  place,  which  ended  in 
his  adoption  of  the  views  of  the  Unitarians.  The  resignation  of  his 
living  and  the  loss  of  the  tutorship  followed  of  course ;  but  the  laws 
of  the  University  still  allowed  him  to  retain  his  fellowship.  After 
some  years  of  travel  he  returned  to  Cambridge,  and  occupied  him- 
self further  in  the  study  of  Hebrew  and  divinity.  In  1793,  a  pam- 
phlet, entitled  "  Peace  and  Union  recommended  to  the  Associated 
Bodies  of  Republicans  and  Anti-republicans,"  was  published  by  him, 
which  contained  distinct  expressions  of  dislike  to  the  doctrines  and 
discipline  of  the  Established  Church.  Immediately  upon  the  publica- 
tion of  this  pamphlet,  both  his  college  and  various  members  of  the 
senate  commenced  proceedings  against  Mr.  Frend.  The  master  and 
fellows  of  the  former  (by  seven  to  four)  "  removed  "  him  from  re- 
sidence in  college,  until  proof  of  "  good  behaviour,"  and  this  sen- 
tence was  confirmed  by  the  visitor.  Thirty-four  members  of  the 
senate  cited  the  author  of  the  pamphlet  before  the  Vice-chancellor 

[•  A  notice  of  the  proceedings  of  the  Society  for  January  will  be  found 
at  p.  397,  and  of  those  for  March  at  p.  477  of  the  present  volume.] 


Royal  Astronomical  Society.  5 1 1 

(Dr.  J.  Milner),  and  a  trial  took  place  in  his  court,  which  lasted  eight 
days.  The  result  was,  that  a  form  of  recantation  was  proposed  to 
Mr.  Frend,  which  he  refused  to  sign ;  and  sentence  of  "  banish- 
ment "  from  the  University  was  passed.  This  banishment  is  not 
expulsion,  as  persons  unacquainted  with  the  University  generally 
believe,  but  a  deprivation  of  the  right  to  reside  within  the  limits  of 
the  University;  and,  accordingly,  though  the  sentence  was  confirmed 
on  appeal,  Mr.  Frend  continued  to  hold  his  fellowship  till  his  mar- 
riage, and  remained  to  the  day  of  his  death  a  Master  of  Arts,  and  a 
member  of  Jesus  College.  He  retired  of  course  from  Cambridge, 
and  came  to  London,  where  he  maintained  himself  till  1806,  by 
adding  the  profits  of  teaching  and  writing  to  the  income  derived 
from  his  fellowship.  When  the  Rock  Life  Assurance  was  founded 
(1806),  Mr.  Frend,  who  had  previously  been  consulted  in  the  for- 
mation, was  appointed  actuary  of  that  company,  a  post  in  which  he 
remained  until  a  severe  illness  compelled  him  (in  1826)  to  retire 
from  active  life.  His  health,  however,  recovered,  and  he  continued 
his  mental  employments  with  an  activity  very  unusual  at  his  age, 
until  the  beginning  of  the  year  1840,  when  he  was  attacked  by 
paralysis,  under  which  he  lingered  with  almost  total  loss  of  speech 
and  motion,  though  with  the  smallest  possible  decay  of  mind  or 
memory,  until  February  21  of  the  last  year,  when  he  closed  a  life, 
which  is  regarded,  even  by  those  who  differed  from  him,  as  a  splendid 
example  of  honesty  in  the  pursuit  of  truth,  and  of  undaunted  deter- 
mination in  the  assertion  of  all  that  conscience  required. 

The  losses  and  inconveniences  which  attended  his  banishment 
from  college  were  not  among  the  greatest  risks  which  he  ran.  At 
a  subsequent  period,  when  the  political  struggle  was  at  its  height, 
and  government  prosecutions  were  frequently  directed  against  the 
mere  expression  of  opinion,  Mr.  Frend  was  one  of  the  foremost 
among  the  despised  minority  which  advocated  emancipation  and  en- 
franchisement for  all  who  were  under  religious  or  political  disqualifi- 
cations. At  the  time  of  certain  of  the  prosecutions  alluded  to,  it 
was  currently  said,  that  had  the  government  succeeded  in  obtaining 
convictions,  there  was  an  intention  of  instituting  several  more  ;  and 
Mr.  Frend,  it  was  stated,  was  to  have  been  one  of  the  defendants. 
This  supposition  cannot  now  be  verified,  even  if  it  were  true ;  but 
the  rumour  itself  constitutes  its  object  one  of  the  leading  opponents 
of  the  system  which  has  since  been  so  materially  modified.  With 
his  political  writings*,  of  which  there  were  several,  we  have  here 
nothing  to  do,  any  more  than  with  those  of  a  religious  character. 
A  true  account  of  his  scientific  views  cannot  be  easily  given  in  a 
short  space  ;  nor  can  reasons  for  enlargement  be  better  given  than 
in  the  description  itself  of  these  views. 

It  generally  happens  that  in  recording  the  career  of  our  departed 
members,  we  have  little  to  say  on  their  opinions,  but  only  to  specify 
the  manner  in  which  they  carried  them  into  practice ;  and  small 

*  The  titles  of  these  will  be  found  in  the  Gentleman's  Magazine  for 
May  1841  (pp.  541-543). 


512  Royal  Astronomical  Society. 

space  may  serve  for  great  results.  In  the  present  instance  we  have 
to  point  out  the  singularities  of  thought  which  made  Mr.  Frend  the 
last,  we  should  suppose,  of  the  learned  Anti-Newtonians,  and  a  noted 
oppugner  of  all  that  distinguishes  algebra  from  arithmetic.  Opposi- 
tion to  the  theory  of  gravitation  must  in  future  be  left  to  those  whose 
mechanics  do  not  distinguish  velocity  from  force ;  and  the  rejection 
of  the  distinctive  principles  of  algebra  to  those  who  would  teach  like 
philosophers  what  they  have  learnt  like  schoolboys,  without  going 
through  any  intermediate  stage.  But  the  subject  of  the  present  me- 
moir stands  in  neither  of  these  predicaments ;  and  it  would  be  highly 
interesting  in  itself,  and  no  less  than  due  to  expiring  tenets,  to  spe- 
cify the  probable  influences  under  which  such  a  mind  as  that  of  Mr. 
Frend  directed  him  to  stand  quite  alone  among  men  of  his  philoso- 
phical acquirements ;  especially  when  it  is  considered  that,  up  to 
the  age  of  thirty-six,  he  had  been  a  successful  teacher  of  those  scien- 
tific doctrines  which  he  afterwards  opposed,  both  by  serious  argu- 
ment and  ridicule*. 

Undoubtedly  the  prime  mover  of  this  curious  change  was  the  al- 
teration which  took  place  in  his  doctrinal  views  of  religion.  Having 
been  led  to  conclude  that  he  had  been  betrayed  by  authority  into 
the  belief  of  propositions  both  inexplicable  and  false,  the  tendency 
to  think  that  the  inexplicable  must  be  false,  or  at  least  to  regard  the 
former  with  strong  suspicion,  was  a  necessary  ingredient  of  his  fu- 
ture reflections  on  all  subjects.  The  manner  in  which  several  leading 
doctrines  of  physics  and  mathematics  had  been  handled  by  names  of 
celebrity,  was  highly  calculated  to  call  out  this  disposition.  The 
doctrine  of  attraction, — a  mysterious  connexion  between  matter  and 
matter,  with  no  existence  but  in  its  results  ;  the  theory  of  quantities 
less  than  nothing,  a  phrase  which,  arithmetically  considered,  is  a 
simple  contradiction  of  terms,  were  adopted  at  the  time  when  Mr. 
Frend  taught  in  a  most  positive  and  substantive  sense,  by  the  ma- 
jority of  investigators  and  all  elementary  writers. 

It  was  in  vain  that  Newton,  obviously  hoping  for  some  further 
elucidation  of  his  great  regulator,  concluded  the  Principia  with  a 
caution  that  he  had  not  yet  (nondum)  found  out  the  source  of  gravi- 
tation ;  his  successors  and  commentators,  with  one  voice,  pronounced 
him  the  discoverer  of  the  final  mechanical  cause  of  the  planetary 
motions ;  and  popular  writers,  who  seldom  refuse  to  say  B  when 
their  leaders  have  said  A,  added  that  Newton  had  found  out  why 
water  runs  down  hill.  With  respect  to  algebra,  the  matter  was  still 
worse.  Euler  asserted  downright  that  a  penniless  man,  fifty  crowns 
in  debt,  has  fifty  crowns  less  than  nothing  ;  and  offered  proof.  He 
assumes  that  a  gift  of  fifty  crowns  would  make  this  man  richer ;  and 

*  In  a  magazine  which  lasted  for  a  few  months  of  1803,  '  The  Gentle- 
man's Monthly  Miscellany,'  of  which  Mr.  Frend  was  editor,  or  co-editor, 
is  an  article  by  him,  entitled"  Pantagruel's  Decision  of  the  Question  about 
Nothing,"  in  which  the  manner  of  Rabelais  is  so  well  caught,  that  any  one 
on  a  first  perusal  would  think  it  likely  to  be  an  actual  adaptation  or  parody, 
until  a  search  through  the  writings  of  Rabelais  satisfied  him  that  it  was 
simple  imitation.    It  is  a  satire  against  some  parts  of  algebra. 


Royal  Astronomical  Society.  513 

supposing  him  to  employ  the  gift  in  the  payment  of  his  debts,  then 
concludes  that  he  had  less  than  nothing,  because,  being  now  richer 
than  before,  he  has  only  nothing.     Others  admitted  the  negative 
and  impossible  quantities  as  mysteries,  and,  reversing  Mr.  Frend's 
process,  brought  them  forward  as  auxiliaries  to  the  mysteries  of  the 
orthodox  forms  of  Christanity ;  a  practice  not  extinct  in  our  own 
day,  even  after  all  that  was  inexplicable  about  impossible  quantities 
has  disappeared.      At  the  time  when  Mr.  Frend  first  thought  on 
the  subject,  the  assertion  of  mystery  was  the  escape  from  the  con- 
fession of  incompleteness ;  the  great  mass  of  readers  followed  with 
implicit  confidence,  while,  of  those  who  thought  for  themselves,  an 
enormous  majority  was  too  sensible  of  the  value  of  the  results  of 
algebra  to  abandon  it  on  account  of  difficulties.     Some  few  rejected 
the  peculiar  doctrines  of  algebra  altogether ;  among  whom  those  of 
most  note  were,  in  succession,  Robert  Simson,  Baron  Maseres,  and 
Mr.  Frend.     Most  of  those  who  were  independent  of  authority  united 
in  blaming  the  method  of  the  elementary  writings,  and  were  content 
to  hope  that  a  palpable  guide  to  truth  would  not  always  be  without 
rational  connexion  with  undeniable  axioms.     Woodhouse,  the  re- 
storer of  thought  on  first  principles  at  Cambridge,  in  a  letter  to  Baron 
Maseres,  preserved  among  Mr.  Frend's  papers,  and  dated  November 
16,  1801,  distinctly  lays  it  down  that,  in  these  matters,  it  is  not  the 
principles  which  prove  the  conclusions,  but  the  truth  of  the  conclu- 
sions which  proves  that  there  must,  somewhere  or  other,  be  prin- 
ciples.    "  Whether  or  not,"  says  he,  "  I  have  found  a  logic,  by  the 
rules  of  which  operations  with  imaginary  quantities  are  conducted,  is 
not  now  the  question :  but  surely  this  is  evident,  that,  since  they 
lead  to  right  conclusions,  they  must  have  a  logic."     And  he  goes  on 
thus  :  "  Till  the  doctrines  of  negative  and  imaginary  quantities  are 
better  taught  than  they  are  at  present  taught  in  the  University  of 
Cambridge,  I  agree  with  you  that  they  had  better  not  be  taught ; 
and  the  plan  of  our  system  of  mathematical  education,  much  as  it  is 
praised,  needs,  in  my  opinion,  considerable  alteration  and  reform ; 
and  perhaps  you  think  that  our  late  mathematical  publications  will 
not  much  increase  the  love  or  improve  the  taste  for  luminous  and 
strict  deduction."     As  concerns  the  mystics,  then,  there  is  no  need 
to  object  to  Mr.  Frend's  entire  abandonment  of  their  principles,  but 
the  reverse ;  for  it  may  be  asserted  that  most  of  those  who  thought 
about  first  principles   did  the    same.      Those    who    imposed   on 
matter,  in  the  name  of  Newton,  a  primary  power  of  attracting  other 
matter,  with  those  who  could,  on  their  own  definitions,  be  made  to 
say  that  a  command  to  subtract  2,  repeated  as  many  times  as  there  are 
units  in  a  command  to  subtract  3,  gives  a  command  to  add  6,  ought  to 
have  been  surprised  that  they  found. so  little  opposition. 

But  the  circumstance  relative  to  Mr.  Frend's  ultimate  views  which 
is  peculiar  to  himself  and  which  cannot  be  remembered  without  sur- 
prise, is,  that  in  clearing  the  trammels  of  mystery  he  had  to  force  so 
thick  an  enclosure,  that  he  left  behind  him  not  only  the  mysterious 
explanation,  but  the  very  facts  which  were  professed  to  be  explained, 
and  which,  it  may  be  thought,  could  have  admitted  of  no  doubt.  It 
Phil.  Mag.  S.  3.  No.  141.  Suppl.  Vol.  21.  2  M 


514  Royal  Astronomical  Society. 

seems  to  any  one  who  reads  his  writings,  that  he  means  that  New- 
ton had  done  nothing  out  of  mathematics,  and  that  the  results  of 
algebra  are  all  delusion.  That  the  planets,  attraction  or  no  attrac- 
tion, move  about  the  sun,  and  are  disturbed,  precisely  as  it  would 
be  if  there  were  attraction ;  that  the  truth  of  an  equation  though 
produced  by  aid  of  impossible  quantities,  may  be  verified  by  nume- 
rical computation — may  be  made  purely  experimental  realities,  and 
would,  to  most  minds  as  well  acquainted  with  the  subject  as  that  of 
Mr.  Frend,  remain  true,  even  though  attraction  were  the  atheism 
which  some  formerly  called  it,  and  the  doctrine  of  negative  quan- 
tities were  a  part  of  the  black  art.  Nor  would  it  have  been  won- 
derful if  he  had  rejected  incomplete  explanations  in  elementary 
writing,  the  object  of  which  is  to  teach  clear  results  of  clear  prin- 
ciples. But  there  was  more  than  this :  sometimes,  though  rarely, 
he  seemed  to  have  a  power  of  admitting  the  facts  as  facts ;  but  for 
the  most  part,  when  they  were  presented  to  him  in  conversation,  his 
mind  did  not  appear  capable  of  dwelling  on  them  long  enough  to 
decide  whether  an  answer  was  required  or  not ;  they  seemed  to  slip 
like  water  through  a  sieve.  In  this  there  was  neither  affectation 
nor  evasion ;  it  was  a  peculiar  state  of  mind  with  regard  to  what 
could  be  contemplated  as  a  scientific  truth,  and  may  be  partly  ex- 
plained. 

Mr.  Frend  had  an  admiration  of  simplicity,  and  an  indisposition  to 
arrive  at  complex  results,  which  was  perhaps  a  consequence  of  the 
desire  to  have  no  secret  in  philosophy.  Next  to  the  abandonment 
of  all  that  was  difficult  to  explain,  followed  the  practical  rejection  of 
every  thing  in  which  the  mind  could  not  hold  the  full  explanation 
at  once  before  itself,  in  all  its  parts.  The  simple  theory  of  num- 
bers, that  is,  of  integer  numbers,  was  therefore  naturally  a  favourite 
study ;  and  this  branch  of  mathematics  is  well  known  to  be  an  ex- 
tremely powerful  stimulant  of  that  disposition  which  leads  to  its 
pursuit.  Legendre  has  said  that  it  almost  always  becomes  a  species  of 
passion  with  those  who  give  themselves  to  it  at  all.  With  Mr.  Frend  it 
went  still  further ;  an  equation  with  a  fractional  root,  even  if  commen- 
surable, was  a  pseudo- equation :  and  a?2 +y2= 1,  x  and  y  being  rational 
fractions,  was  an  illegitimate  child  of  #2  -j-  y2  =  z%,  x,  y,  and  z  be- 
ing integers.  In  this  particular  Mr.  Frend  differed  greatly  from 
another  remarkable  person,  his  own  most  intimate  friend  Baron 
Maseres,  whose  leading  idea  it  seems  to  have  been  to  calculate  more 
decimal  places  than  any  one  would  want,  and  to  reprint  the  works 
of  all  who  had  done  the  same  thing. 

There  was  also  another  peculiar  circumstance  which  no  doubt 
had  considerable  effect.  Mr.  Frend  had  studied  Hebrew  thoroughly, 
and  was,  in  the  opinion  of  learned  Jews,  better  versed  in  that  lan- 
guage than  any  English  Christian  of  his  day.  No  one  who  became 
acquainted  with  him  could  long  avoid  noticing  the  interest  which  he 
took  in  every  matter  directly  or  indirectly  concerning  the  history 
and  progress  of  Christianity.  This  knowledge  of  their  language, 
history,  and  customs,  with  a  community  of  opinion  on  the  nature  of 
the  Deity,  led  him  much  into  the  acquaintance  of  his  elder  brethren, 


Royal  Astronomical  Society.  515 

as  he  frequently  termed  them,  of  the  Jewish  race ;  and  he  would 
have  held  any  biography  of  himself  very  imperfect  which  omitted  to 
note  how  strongly  he  felt  toward  their  persuasion.     It  seldom  hap- 
pens that  any  person  devotes  himself  so  keenly  to  any  history  with- 
out imbibing  some  opinion  of  the  superiority  of  its  subjects ;  and 
Mr.  Frend  carried  to  the  very  verge  of  paradox,  or  it  may  be  a  little 
beyond,  the  notion  that  the  mathematical  and  astronomical  science 
of  ancient  Judea  was  substantially  equal  at  least  to  that  of  any 
period  of  modern  Europe,  not  excepting  the  present.     Their  lunar 
calendar  was  as  good  as  if  it  had  been  made  from  modern  observa- 
tions, and  much  better  adapted  to  represent  a  long  period  than  any 
other ;  as  much  of  pure  mathematics  as  any  one  ought  to  admit 
flourished  among  them  in  the  time  of  Solomon.    It  is  needlessto  say, 
that  not  a  vestige  of  historical  evidence  was  ever  produced  in  favour 
of  these  opinions,  nor  did  we  ever  hear  of  any  modern  Jew  who  had. 
carried  his  notions  of  the  learning  of  his  ancestors  to  such  a  length. 
Among  modern  nations,  Mr.  Frend  had  a  peculiar  respect  for  the 
Chinese,  and  was  impressed  with  the  opinion  (not  by  any  means 
peculiar  to  himself)  that  their  government  and  social  state  is  a  model. 
The  rudiments  of  science  which  he  found  among  these  nations,  the 
ancient  Hebrews  and  the  modern  Chinese,  were  easily  magnified  by 
his  temperament,  which  was  both  sanguine  and  contemplative,  into 
as  much  of  astronomy  and  arithmetic  as  he  had  been  able  to  save 
from  the  pollution  of  attraction  and  negative  quantities;  conse- 
quently, these  countries  were  the  depositories  of  real  science,  un- 
corrupted  by  sophistry.     For  the  ancient  Greeks  and  their  writings 
he  had  an  open  contempt ;  they  were  children  who  had  learned  of 
the  Jews,  and  spoiled  their  masters'  doctrines :  the  good  was  due 
to  their  teachers,  the  bad  was  their  own.     All  this  time,  and  in  the 
midst  of  such  strange  singularities  of  opinion  as  were  never  long 
absent  from  his  mind,  there  was  an  eagerness  to  see  the  good  of 
every  thing  actually  present,  which  made  his  approbation  very  easy 
to  gain.     No  one  who  talked  with  him  could  soon  fathom  the  wide 
difference  of  sentiment  between  the  two ;  for  whatever  might  be  the 
subject,  there  was  a  side  on  which  it  could  be  favourably  viewed  ; 
and  for  that  side  Mr.  Frend's  mind,  or  that  part  of  it  which  regu- 
lated his  first  expressions,  had  the  quality  (we  must  not  say  the  at- 
traction) of  a  magnet.     His  persuasion  of  the  rapid  advances  which 
his  contemporaries  were  making  in  morals,  arts ,  and  even  sciences 
(however  corrupted),  was  a  spring  of  comfort  to  his  age  which  never 
ran  dry  ;  and  his  interest  in  every  thing  new,  which  promised  im- 
provement to  any  class  of  mankind,  in  any  one  of  those  particulars, 
was,  even  after  he  was  unable  to  speak  or  move,  a  commanding  in- 
stinct, which  he  could  not  have  disobeyed  if  he  would.     This  un- 
varying effort  to  detect  good  in  whatever  came  before  him  was  es- 
sentially linked  to  his  religious  feelings,  the  source  of  his  daily  com- 
fort, by  the  view  which  he  never  ceased  to  take  of  the  ultimate  con- 
sequences of  Christianity ;  which  he  looked  upon  as  the  gradual  re- 
storer of  mankind  to  a  state  of  perfect  goodness  and  knowledge. 
Every  advance  in  art,  learning,  or  science, — every  amelioration  of 

2M2 


516  Royal  Astronomical  Society. 

social  evils, — every  improvement  in  the  law, — every  evidence,  how- 
ever slight,  of  disposition  to  act,  think,  or  hope,  for  the  better, 
brought  before  him  his  cherished  prospect  of  the  final  state  of  man- 
kind, and  was,  in  his  opinion,  only  a  step  towards  it.  The  conse- 
quence was,  that  any  one  who  would  wish  to  describe  his  age,  must 
simply  invert  each  and  all  of  the  characteristics  which  Horace* 
makes  significative  of  the  advanced  periods  of  life. 

Mr.  Frend's  scientific  writings  were  particularly  distinguished  by 
simplicity  and  earnestness.     The  greater  part  of  the  whole  consists 
in  short  pamphlets,  or  communications  to  periodical  publications ; 
and  many  proofs  might  be  given,  both  of  the  extreme  importance  he 
attached  to  truth,  and  of  his  conviction  that  error,  even  in  matters 
of  science,  is  a  noxious  weed  in  the  field  of  morals.     His  principal 
distinct  writings  on  subjects  of  science  are  his  'Algebra'  (Part  i.  1796, 
Part  ii.  1799),  and  his  '  Evening  Amusements'  (1804-1822).      The 
latter  was  an  astronomical  elementary  work  of  a  new  character,  which 
had  great  success ;  and  the  earlier  numbers  went  through  several 
editions.     It  embraces  a  metonic  cycle,  and  therefore  describes  the 
places  of  the  moon,  in  a  manner  which  would  make  it  useful  for  a 
considerable  time  to  come,  in  the  elementary  instruction  for  which 
it  was  intended.     This  present  year  is  that  which  answers  to  1804, 
so  that  the  opportunity  to  repeat  the  process  of  instruction,  so  far 
as  the  moon  is  concerned,  has  just  commenced.     The  phsenomena 
of  the  different  months  are  described,  and  to  each  month  is  usually 
attached  a  short  religious  reflection,  an  account  of  some  astronomical 
process  or  discovery,  a  hit  at  the  Newtonian  philosophy,  or  some 
such  preface.     We  do  not  see  much  acquaintance  with  the  new  doc- 
trines of  physics,  which  had  then  excited  attention  for  some  years  ; 
but  it  must  be  remembered  that  a  man,  who  took  his  degree  at  Cam- 
bridge in  1780,  had  very  little  training  in  experimental  deduction 
apart  from  mathematics. 

Mr.  Frend's  scientific  peculiarities  strongly  illustrate  what  those 
who  have  carefully  considered  the  reading  of  that  time  will  perhaps 
think  to  be  the  natural  consequence  of  it,  upon  an  exceedingly 
honest,  clear,  and  decided  mind,  placed  in  circumstances  favourable 
to  the  development  of  opposition.  The  Cambridge  student  was 
isolated  from  experimental  physics  by  the  habits  of  his  university, 
and  from  the  progress  of  mathematics  by  its  adherence  to  the  flux- 
ional  notation.  In  essentials,  the  academic  system  was  nearer  to 
what  it  might  have  been  at  the  death  of  Newton  than  those  who 
now  see  its  state  could  readily  imagine  to  be  possible :  the  theory 
of  gravitation  was  taken  wholly  and  solely  from  the  Principia ;  no 
Englishman  had  made  the  smallest  addition  to  it;  and  Clairaut, 
D'Alembert,  &c.  were  only  known  by  name  as  French  philosophers, 

*  "  Multa  senem  circumveniunt  incommoda ;  vel  quod 
Quaerit,  et  inventis  miser  abstinet,  ac  timet  uti, 
Vel  quod  res  omnes  timide  gelideque  ministrat ; 
Dilator,  spe  longus,  iners,  avidusque  futuri, 
Difficilis,  querulus,  laudator  temporis  acti 
Sepuero,  censor  castigatorqueminorum." 


Royal  Astronomical  Society.  517 

the  most  odious  appellation  of  the  time.  One  question  might  be 
asked  which  would,  perhaps,  add  some  force  to  the  preceding  re- 
marks, if  reasons  for  an  answer  were  sought : — How  came  the  men 
of  science,  who  were  bred  at  our  English  universities,  to  let  Priestley, 
whose  life  was  one  turmoil  of  controversy,  and  who  visibly  must  have 
written  four  pages  a-day,  or  thereabouts,  of  theological  discussion 
during  his  whole  experimental  career,  run  off  with  such  a  splendid 
portion  of  the  first-fruits  of  real  chemistry  ? 

The  other  work  of  Mr.  Frend,  his  '  Elements  of  Algebra,'  will  lead 
every  one  who  peruses  it  to  think,  with  sincere  regret,  of  his  having 
preferred  rejection  to  amendment ;  and  will  be  a  lesson  to  writers 
yet  to  come,  that  they  should  let  that  stand  which  appears  to  lead 
to  truth,  whatever  warning  they  may  think  it  necessary  to  give  that 
the  reason  why  it  does  so  lead  is  imperfectly  understood.  It  is,  on 
the  points  which  it  treats,  the  clearest  book  in  our  language.  Some- 
thing of  this  is  due  to  the  rejection  of  difficulty ;  something  to  the 
use  of  no  problems  except  those  which  can  be  answered  in  integers ; 
but  there  remains  enough  to  show  that  a  work  from  such  a  writer, 
which  should  have  taken  algebra  as  it  stood,  distinguishing  the  part 
of  which  the  logic  was  then  complete  from  that  of  which  the  prin- 
ciples remained  insufficiently  understood,  would  have  been  the  most 
valuable  present  which  could  have  been  made  to  the  elementary 
student,  and  would,  perhaps,  have  greatly  accelerated  the  transition 
to  the  present  state  of  the  science,  in  which  none  need  find  a  my- 
stery. In  all  probability,  the  attack  of  Mr.  Frend  did  materially  in- 
fluence this  result.  Among  his  papers  is  preserved  a  letter  to  him 
from  M.  Buee,  a  Frenchman  residing  in  England,  dated  June  21, 
1801,  containing  the  form  in  which  the  perusal  of  Mr.  Frend's  work 
made  the  writer  put  together  his  own  views  of  the  subject ;  and  ad- 
mirably expressed.  Of  course  it  cannot  be  said  how  much  sugges- 
tion was  derived  from  the  necessity  of  replying  to  specific  objections ; 
what  is  certain  is,  that  in  a  few  years  from  that  time,  this  same  M. 
Buee  was,  though  in  an  imperfect  manner,  what  Dr.  Peacock  calls 
the  first  formal  maintainer  of  that  exposition  which  removes  the 
long  standing  difficulty. 

Finally,  whatever  may  be  our  opinion  on  the  peculiarities  of  Mr, 
Frend's  views,  we  must  remember  with  high  satisfaction  that  he  was, 
during  the  last  years  of  his  life,  one  of  our  Fellows  ;  and,  also,  that  no 
narrow  idea  of  the  necessity  of  conformity  of  opinion  prevented  a 
man  of  his  intellectual  station  from  being  called  to  the  Council  of  the 
Society.  The  sincere  regret  with  which  the  Council  announces  the 
loss  which  our  Body  has  sustained  is  materially  lessened  by  the  reflec- 
tion that  his  extensive  learning,  practical  wisdom  in  the  affairs  of  life, 
chivalrous  assertion  of  all  that  he  thought  true,  and  extraordinary 
benevolence  of  feeling,  were  permitted  a  long  and  useful  career,  ter- 
minated only  by  natural  decay,  and  followed  by  the  love  of  many, 
and  the  respect  of  all. 

It  is  well  known  to  many  of  the  Members  of  this  Society  that  an 
enlarged  and  improved  Catalogue  of  the  Stars,  arranged  after  the 
manner  of  the  Catalogue  of  this  Society,  has  been  a  long  time  in 


518  Royal  Astronomical  Society. 

progress,  under  the  auspices  of  the  British  Association.  That  work 
is  now  nearly  completed,  and  ready  for  the  press,  and  will  contain 
above  8000  stars.  To  each  star  will  be  annexed  not  only  the  annual 
precession,  but  also  the  secular  variation  of  such  precession,  and  the 
proper  motion  when  it  can  be  ascertained.  The  usual  constants  for 
determining  the  apparent  positions  of  the  stars  at  any  required 
epoch  will  also  be  given.  This  work  cannot  fail  of  being  a  valuable 
addition  to  the  resources  of  the  astronomer. 

The  Members  may  be  interested  in  learning  that  the  Standard  Scale 
of  this  Society  has  been  reported  to  Her  Majesty's  Government, 
as  one  of  the  best  means  of  regaining  an  accurate  determination  of 
the  Standard  Yard  that  was  destroyed  in  the  conflagration  of  the  two 
Houses  of  Parliament ;  and  that  an  indirect  overture  has  been  made  for 
the  acquisition  of  it,  should  the  Government  eventually  consider  it 
desirable.  The  Council  apprehend  that  the  Members  would  readily 
accede  to  any  arrangement  in  this  respect,  which  would  promote  the 
object  that  the  Government  has  in  view,  and  at  the  same  time  not 
be  injurious  to  the  interests  of  the  Society. 

The  British  Association  having  appointed  a  Committee  to  consider 
the  propriety  of  revising  and  re-arranging  the  constellations  in  the 
heavens,  Sir  John  Herschel  has  drawn  up  an  interesting  paper  on  this 
subject,  which  has  been  read  before  the  Society,. and  printed  in  the 
forthcoming  volume  of  the  Memoirs.  As  it  was  considered  desirable 
that  an  early  and  extensive  circulation  of  his  views  on  this  subject 
should  take  place,  the  Council  ordered  an  additional  number  of 
copies  of  this  paper  to  be  printed,  which  have  been  generally  dis- 
tributed, with  a  view  of  drawing  the  attention  of  astronomers  to  this 
branch  of  the  science.  Sir  John's  revision  has  been  confined  to 
the  southern  hemisphere,  where  the  greatest  confusion  prevails  in 
the  nomenclature  of  the  stars  and  in  the  distribution  of  the  con- 
stellations ;  and  if  the  reform,  which  is  here  [suggested  in  the  south, 
should  meet  the  approbation  of  astronomers,  it  may  become  a  matter 
of  consideration,  whether  the  principle  may  not  be  extended  into  the 
northern  hemisphere,  which  has  been  sadly  confused  by  modern 
innovations. 

Since  the  last  Anniversary,  Her  Majesty's  Government  has  put 
the  Society  in  possession  of  two  rooms  on  the  basement  story  of  the 
present  building ;  which  have  been  cleaned  out  and  appropriated  for 
the  erection  of  any  apparatus  that  may  be  required  for  pendulum  ex- 
periments, or  for  prosecuting  any  other  investigations  that  may  be 
carried  on  in  such  apartments. 

It  had  long  been  a  subject  of  regret  that  the  immense  magazine 
of  facts  contained  in  the  Annals  of  the  Royal  Observatory  from  the 
time  of  Bradley's  appointment,  downwards,  till  a  very  recent  epoch, 
should  remain  in  a  great  degree  unavailable  for  astronomical  use. 
Our  illustrious  associate  Bessel,  in  his  Fundamenta  Astronomies,  cor- 
rections to  the  solar  tables,  and  finally  by  his  Tabula  Regiomontana;, 
rendered  this  vast  labyrinth  permeable,  and  extracted  and  exhibited 
in  a  finished  shape  much  of  its  valuable  contents.  Some  years  ago, 
the  British  Association  proposed  to  the  Government  the  reduction  of 


Royal  Astronomical  Society.,  519 

all  the  Greenwich  planetary  observations  under  the  gratuitous  super- 
intendence and  responsibility  of  the  present  Astronomer  Royal,  and 
at  his  own  suggestion.  That  work  is  now  completed,  and  it  is  un- 
derstood that  the  funds  required  for  printing  the  results  will  be  fur- 
nished by  the  Board  of  Admiralty.  The  planetary  places  are  com- 
pared with  the  best  existing  tables,  and  the  difference  in  heliocentric 
longitude  and  latitude  given  exactly  as  in  the  recent  volumes  of  the 
Greenwich  Observations,  with  a  term  which  takes  into  account  the 
errors  of  the  solar  tables,  should  any  sensible  errors  be  therein  found. 
It  need  not  be  said  to  the  members  of  this  meeting  that  every  care 
has  been  taken,  by  duplicate  computations  and  frequent  comparisons, 
to  attain  all  practicable  accuracy.  The  geometer  who  undertakes 
the  revision  of  the  theory  of  a  planet  will  now  have  no  labour  which 
could  be  spared,  and  will  be  freed  from  every  difficulty  which  is  not 
inherent  in  the  problem  itself;  so  that  we  may  feel  tolerable  confi- 
dence a  few  years  will  see  us  in  possession  of  tables  very  far  indeed 
advanced  towards  perfection. 

But  this  work,  laborious  as  it  has  been,  yields  in  importance  to 
that  which  has  been  subsequently  undertaken  by  the  Astronomer 
Royal  (also  gratuitously),  the  reduction  of  all  the  Greenwich  ob- 
servations of  the  moon,  from  Bradley  downwards,  together  with  a 
comparison  of  the  observed  places  with  those  deduced  from  Plana's 
theory.  Considerable  progress  has  already  been  made.  The  R.  A. 
and  N.  P.  D.  of  the  moon's  bright  limb,  with  the  corresponding 
mean  solar  time,  are  computed;  MS.  tables,  consisting  of  an  ex- 
tension of  Damoiseau's  tables  for  1824,  modified  by  the  introduction 
of  Plana's  coefficients  and  new  terms,  are  nearly  ready.  The  skele- 
ton forms  are  prepared,  and  some  steps  in  the  computations  taken. 
The  liberality  of  Her  Majesty's  Government  has  enabled  the  Astrono- 
mer Royal  to  employ  fourteen  calculators  on  the  work,  which  is  con- 
sequently advancing  with  all  possible  speed  and  ceconomy.  Let  us 
hope  that  no  pause  will  be  made  until  a  new  set  of  lunar  tables  of 
home  manufacture  are  produced,  which  shall  define  the  place  of  our 
hitherto  incorrigible  satellite  with  the  accuracy  of  the  best  observa- 
tions, and  sufficiently  for  the  nicest  purposes  of  geography.  Your 
Council  feel  that  you  will  heartily  join  with  them  in  their  respect 
for  the  talents,  disinterested  activity,  and  official  piety  of  the  Astro- 
nomer Royal,  and  in  thanks  to  the  Government  for  its  discriminating 
and  liberal  patronage  of  our  science. 

The  Council  are  glad  to  have  it  in  their  power  to  report  to  the 
meeting,  that  the  difficulties  which  seemed  to  he  in  the  way  of  suc- 
cessful completion  of  the  Cavendish  experiment  have  been  removed, 
by  new  precautions  against  the  radiation  of  heat  from  the  large  balls. 
Though  many  experiments  may,  -in  the  early  investigations,  have 
been  apparently  wasted,  yet  in  reality  much  good  must  result  from 
the  new  light  thus  thrown  upon  the  details  of  the  operation  itself, 
and  on  the  torsion-balance,  which  is  the  principal  instrument  em- 
ployed. Considering  the  nature  of  the  quantity  required,  the  results 
begin  to  assume  a  degree  of  accordance  with  each  other  which  pro- 
mises a  very  accurate  determination  of  that  great  element  of  the 


520  Royal  Astronomical  Society. 

solar  system,  the  mean  density  of  the  earth.  The  slight  discrepancies 
which  still  remain,  and  which  appear  to  show  that  something  de- 
pends on  the  substance  employed,  and  more  on  unknown  circum- 
stances connected  with  the  torsion-balance  itself,  are  not  such  as  to 
throw  any  reasonable  doubt  on  the  density  obtained  being  true 
within  less  than  a  hundredth  part  of  the  whole.  So  much  can  safely 
be  said  at  the  present  time ;  and  it  is  not  improbable  that  a  still 
smaller  limit  of  error  may  be  substituted  for  the  one  just  named. 
Mr.  Baily's  final  report  may  be  soon  expected,  and  in  the  meantime 
some  detail  of  the  history  of  the  experiment  is  actually  in  the  hands 
of  the  Secretaries,  and  will  shortly  be  read  at  an  ordinary  meeting 
of  the  Society.  The  work  itself  will  form  the  fourteenth  volume  of 
the  Memoirs,  and  a  portion  of  the  tables  is  already  in  the  hands  of 
the  printer. 

The  Council  have  the  satisfaction  of  announcing  that  the  thir- 
teenth volume  of  the  Memoirs  will  be  ready,  perhaps,  before  the 
completion  of  the  twelfth ;  Mr.  Baily,  having  been  lately  engaged 
in  reprinting,  at  his  own  expense,  the  catalogues  of  Ptolemy,  Ulugh 
Beigh,  Tycho  Brahe\  Halley,  and  Hevelius,  in  the  type  and  form  of 
our  Memoirs,  has  offered  the  whole  to  the  Council,  to  form  the 
volume  in  question.  As  might  have  been  expected,  these  catalogues 
have  undergone  such  a  revision  and  comparison  as  will  materially 
increase  their  utility,  and  make  these  integrant  portions  of  the  hi- 
story of  astronomy  familiar  to  the  observer  of  our  own  day,  who  now 
looks  upon  them  as  difficulties,  and  refers  to  them  (if,  indeed,  he 
have  so  much  as  the  means  of  doing  so  at  all)  as  little  as  he  can 
help.  The  outlay  saved  to  the  Society  by  the  manner  in  which  this 
volume  comes  to  us,  though  deserving  and  obtaining  our  warm  ac- 
knowledgements, is  the  least  part  of  the  benefit ;  nor  could  the  Council 
have  omitted  one  word  of  the  preceding  testimony,  if  the  manuscript, 
being,  as  it  is,  such  as  would  gladly  have  been  received;  had  been 
presented  in  the  usual  manner. 

The  whole  of  the  volume  is  printed,  excepting  the  preface,  of 
which  a  circumstance  well  known  to  the  Society  at  large  has  de- 
layed the  execution.  And  here,  though  it  may  be  unusual  to  refer 
to  the  incidents  of  private  life,  yet  the  Council  are  sure  that  this 
meeting  would  feel  disappointed  if  some  opportunity  were  not  given 
to  the  members  of  the  Society  to  congratulate  each  other,  and  Mr. 
Baily,  upon  his  most  welcome  and  providential  escape  from  the 
consequences  of  one  of  those  accidents  to  which  the  inhabitants  of 
crowded  cities  are  daily  exposed  :  an  accident  which,  as  all  present 
remember,  almost  removed  all  hope  of  recovery,  and  made  it  seem 
next  to  impossible  that  life,  if  spared,  should  have  been  again  oc- 
cupied in  the  promotion  of  knowledge,  and  least  of  all  in  active  re- 
search. Seeing  him  once  more  among  us,  in  perfect  health  of  mind 
and  body,  and  remembering  how  much  more  probable  it  lately  ap- 
peared that  we  should  now  be  commemorating  his  innumerable  ser- 
vices to  the  Society  than  anticipating  their  continuance,  the  Council 
drop  the  subject  with  the  expression  of  their  earnest  hope  that  a  life 
preserved  against  all  expectation  may  be  preserved  beyond  all  ex- 


Royal  Astronomical  Society.  521 

pectation,  and  that  a  distinguished  career  may  yet  await  one  of  the 
earliest  and  the  most  indefatigable  friends  of  the  Society. 

In  the  Address  of  the  President  at  the  last  Anniversary  of  the 
Society,  honourable  mention  was  made  of  Mr.  Henderson's  investi- 
gations relative  to  the  presumed  parallax  of  a  Centauri.  These  in- 
vestigations have  been  continued  to  the  present  time  ;  and  from  some 
observations  recently  received  by  him  from  Mr.Maclear,  at  the  Cape 
of  Good  Hope,  he  is  confirmed  in  his  opinion  relative  to  this  subject, 
and  considers  the  parallax  to  be  about  1".  The  Council  trust  that 
they  shall  soon  receive  from  Mr.  Henderson  a  detailed  memoir  on 
this  important  subject,  which  will  then  be  read  at  the  ordinary  meet- 
ing of  the  Society. 

The  Council  regret  that  they  have  to  announce  the  retirement  of 
Lieut.  Raper  from  the  office  of  Secretary  to  this  Society ;  an  office 
which  he  has  filled  with  the  greatest  zeal  and  attention,  and  which 
calls  from  this  meeting  the  expression  of  their  best  thanks.  Nothing 
but  the  love  of  science  and  the  talents  which  he  possesses  could 
have  induced  him  to  take  so  active  and  important  a  duty,  often- 
times at  a  sacrifice  of  private  ease  and  convenience :  but  this  remem- 
brance is  at  once  the  source  of  our  approbation  and  the  cause  of  our 
regret. 

The  Council  trust  that  the  award  of  the  medal  to  Prof.  Hansen  will 
meet  the  approbation  of  the  Society.  The  labours  of  M.  Hansen 
are  well  known  to  those  astronomers  and  mathematicians  who  have 
attended  to,  and  cultivated,  that  branch  of  inquiry  which  more  espe- 
cially relates  to  those  abstruse  and  intricate  points  of  investigation 
that  require  the  greatest  exercise  of  mental  exertion.  The  grounds 
on  which  this  award  has  been  made  will  be  more  fully  explained  in 
the  Address  of  the  President  at  the  close  of  this  Report. 

The  President  {the  Right  Honourable  Lord  Wrottesley)  then  ad- 
dressed the  Meeting  on  the  subject  of  the  award  of  the  Medal,  as  fol- 
lows : — 

Gentlemen, — Since  the  great  discovery  of  the  law  of  gravitation, 
the  means  by  which  the  astronomy  of  the  solar  system  has  been  ad- 
vanced to  its  present  state  of  perfection  are  of  two  distinct  kinds. 
The  first  consists  in  the  collection  of  facts  from  observation, — or,  it 
may  be  said,  in  the  application  of  that  complicated  and  refined  sy- 
stem of  operations  whereby  the  practical  astronomer  is  enabled  not 
only  to  assign  the  exact  positions  which  the  several  bodies  belonging 
to  the  system  occupy  at  the  moment  of  observation,  but  also  to  de- 
termine the  paths  they  describe  in  space,  and  the  laws  by  which 
their  motions  are  governed.  The  second  is  that  which  is  employed 
by  the  geometer.  Setting  out  from  the  law  of  gravitation  as  esta- 
blished by  Newton,  and  borrowing  only  from  observation  the  ele- 
ments which  are  necessary  for  the  institution  of  his  calculus,  his  ob- 
ject is  to  deduce  from  theory  alone  the  whole  of  the  phenomena  of 
the  system,  even  to  their  minutest  details,  and,  by  a  comparison  of 
his  results  with  observation,  to  determine  the  masses  of  the  different 
bodies,  the  influences  which  they  exercise  on  the  motions  of  each 


522  Royal  Astronomical  Society. 

other,  and  the  amount  hy  which  the  elements  of  their  fluctuating 
orbits  deviate  from  their  average  conditions ; — to  express  in  formula? 
the  state  of  the  system  and  the  position  in  space  of  every  body  be- 
longing to  it  at  any  given  instant  in  past  or  future  duration ;  and, 
finally,  to  convert  his  formulae  into  numericalt  ables,  for  the  uses  of 
navigation  and  the  other  important  purposes  to  which  astronomy  is 
subservient. 

It  is  for  researches  in  this  second  department  of  our  science,  un- 
doubtedly the  most  arduous  and  difficult  of  the  two,  that  your  Council 
have  awarded  the  Society's  Gold  Medal  for  the  present  year  to 
Professor  Hansen,  the  Director  of  the  Observatory  at  Seeberg,  and, 
according  to  annual  custom,  the  duty  devolves  on  me  of  stating  to 
you  the  grounds  of  their  decision.  The  subject  is  not  very  suscep- 
tible of  popular  explanation  ;  in  fact,  the  especial  services  which  M. 
Hansen  has  rendered  to  astronomy  consist  in  the  development  of  new 
formulae,  and  the  exhibition  of  new  artifices  of  calculation,  in  the 
remotest  and  most  abstruse  departments  of  mathematical  analysis. 
Nevertheless,  I  trust  I  shall  be  able  to  convey  such  an  idea  of  their 
nature  and  object  as  will  enable  you  at  least  to  appreciate  the  mo- 
tives which  have  influenced  your  Council  in  conferring  on  our  il- 
lustrious Associate  this  testimony  of  the  Society's  approbation. 

In  proceeding  to  determine  the  motions  of  a  celestial  body  urged 
by  a  central  force,  and  disturbed  by  the  action  of  other  bodies,  the 
accelerating  forces  in  the  direction  of  rectangular  coordinates  are 
expressed  by  three  differential  equations  of  the  second  order,  which, 
as  is  well  known,  can  only  be  integrated  by  approximation.  To 
obtain  approximate  integrals,  two  methods  have  been  principally  fol- 
lowed. The  first  consists  in  deducing  from  the  differential  equa- 
tions, expressions  for  the  variations  of  the  radius  vector,  longitude, 
and  latitude  of  the  disturbed  body  in  a  function  of  the  disturbing 
force  and  its  partial  differentials ;  and  in  integrating  these  expres- 
sions, either  by  developing  them  in  series  which  proceed  according 
to  the  powers  of  the  eccentricities  and  inclinations,  or  else  by  the 
method  of  parabolic  quadratures.  This  is  the  most  obvious  method 
of  determining  the  perturbations,  and  also  the  simplest  when  the 
approximations  are  only  carried  to  terms  of  the  order  of  the  eccen- 
tricities and  inclinations  ;  but  when  a  closer  approximation  becomes 
necessary,  and  terms  of  a  higher  order  are  required  to  be  included, 
the  expressions  become  complicated,  and  the  method  accordingly 
loses  its  advantages. 

The  other  method  of  obtaining  approximate  results  is  known  in 
analysis  as  the  method  of  variation  of  arbitrary  constants.  This 
method,  though  undoubtedly  entitled  to  be  regarded  as  one  of  the 
most  ingenious  artifices  of  modern  analysis,  is  suggested  in  a  man- 
ner by  the  peculiar  constitution  of  our  solar  system,  in  which  the 
disturbing  forces  which  act  upon  any  body  bear  so  small  a  propor- 
tion to  the  principal  force  which  determines  the  general  orbit,  that 
the  body  may  be  regarded  as  moving  always  in  an  ellipse,  but  in  an 
ellipse  whose  elements  are  in  a  state  of  continual  though  extremely 
slow  change.  In  accordance  with  this  idea,  the  origin  of  which  may 


Royal  Astronomical  Society,  523 

be  referred  to  Newton  himself,  the  accelerating  forces  which  act  on 
a  celestial  body  are  conceived  to  be  divided  into  two  parts,  one  of 
which  renders  integrable  the  differential  equations  between  the  co- 
ordinates and  the  time,  and  gives  the  elliptic  orbit  which  the  body 
would  describe  about  a  centre  of  force  if  there  was  no  disturbance ; 
while  the  arbitrary  quantities  introduced  by  this  first  integration  are 
supposed  to  be  rendered  variable  by  the  other  part,  and  their  varia- 
tions determined  by  means  of  differential  equations  of  the  first  order, 
whose  integrals  (usually  obtained  by  successive  approximation)  give 
the  elements  of  the  true  perturbed  orbit,  from  which  the  radius 
vector,  longitude,  and  latitude  of  the  body  at  any  given  time  are  com- 
puted. 

The  first  example  of  this  method  of  computing  the  planetary  per- 
turbations was  given  by  Euler  in  the  Berlin  Memoirs  for  1749, 
where  he  obtains  the  differential  equations  of  the  first  order  of  the 
inclination  and  longitude  of  the  node  by  varying  the  arbitrary  con- 
stants which  express  these  two  elements  in  the  elliptic  orbit.  But 
though  Euler  afterwards  succeeded  in  finding  expressions  for  the 
variations  of  some  of  the  other  elements,  the  complete  development 
of  the  method,  and  its  application  not  only  to  physical  astronomy, 
but  to  the  general  theory  of  mechanics,  is  due  to  Lagrange ;  and  it 
forms  the  distinguishing  feature,  so  far  as  dynamics  are  concerned, 
of  the  beautiful  system  of  mathematical  analysis  which  that  illus- 
trious geometer  has  bequeathed  to  science  in  the  Me'canique  Analy- 
tique. 

The  method  of  analysis  which  we  are  now  considering,  is  attended 
with  peculiar  advantages  when  applied  to  the  determination  of  the 
secular  inequalities  of  the  orbits,  in  the  development  of  which  the 
greatest  triumphs  have  been  achieved  of  which  physical  astronomy 
can  boast  since  the  discoveries  of  Newton.     It  was  by  this  means 
that  Lagrange  demonstrated  that  the  greater  axes  of  the  planetary 
orbits  are  affected  by  no  inequalities  independent  of  the  configuration 
of  the  bodies,  and  consequently  that  amidst  all  the  fluctuations  of  the 
system,  the  mean  distances  of  the  planets  from  the  sun,  and  there- 
fore also  their  mean  motions,  remain  for  ever  and  unchangeably  the 
same.     It  was  by  the  same  means  Laplace  formed  exact  expressions 
for  the  secular  variations  of  the  eccentricities  and  inclinations*  and 
thence  proved  that  the  changes  of  those  elements  must  always  be 
inconsiderable ;  that  they  do  not  increase  indefinitely  with  the  time, 
but  after  a  longer  or  shorter  period  again  resume  their  former  values. 
These  conclusions,  which  were  confirmed  by  the  subsequent  and 
more  complete  analysis  of  Poisson,  lead  immediately  to  what  may 
be  regarded  as  the  most  remarkable  triumph  of  modern  science, 
namely,  the  stability  of  the  solar  system  ;  for  they  show  that,  how- 
ever the  motions  and  positions  of  the  several  planets  and  satellites 
may  be  deranged  and  disturbed  by  their  mutual  perturbations,  the 
variations  which  take  place  in  the  magnitudes  and  forms  and  posi- 
tions in  space  of  the  different  orbits  are  not  only  periodic,  but  con- 
fined within  narrow  limits. 

But,  although  in  the  hands  of  these  great  masters  of  analysis  the 


524?  Royal  Astronomical  Society. 

method  of  varying  the  elliptic  elements  led  to  the  sublime  disco- 
veries now  alluded  to,  it  is  not  without  defects,  which  become  parti- 
cularly sensible  in  the  numerical  computations.  Among  these  is 
to  be  reckoned  the  length  of  the  calculations  which  it  renders  ne- 
cessary for  two  reasons  ;  first,  because  the,number  of  elements  of  an 
orbit  being  twice  the  number  of  the  coordinates  which  determine 
the  place  of  the  body,  the  calculation  of  a  much  greater  number  of 
quantities  is  required  than  by  the  first- mentioned  method ;  and,  se- 
condly, because  when  the  perturbations  of  the  elements  have  been 
computed,  there  still  remains  the  labour  of  substituting  the  altered 
elements  in  the  expressions  of  the  coordinates  derived  from  the  el- 
liptic motion,  in  order  to  obtain  the  disturbed  coordinates  and  the 
place  of  the  body  in  its  actual  orbit.  The  principal  defect  of  the 
method,  however,  consists  in  this,  that  the  coefficients  of  the  dif- 
ferent terms  of  the  series  which  express  the  disturbed  elliptic  ele- 
ments have,  in  general,  much  larger  values  than  the  corresponding 
terms  of  the  expressions  of  the  disturbed  coordinates  which  deter- 
mine the  position  of  the  body,  so  that  the  series  expressing  the 
disturbed  elements  converge  slowly,  even  when  they  correspond 
to  small  perturbations  of  coordinates.  If  we  conceive,  for  example, 
a  system  of  forces  of  short  period  to  disturb  the  curvature  of  an 
orbit  many  times  in  a  single  revolution,  it  will  be  easy  to  see  that 
in  each  of  these  periods  the  elements  of  the  orbit  may  have  been 
greatly  altered,  while  the  disturbance  of  coordinates  (of  the  longi- 
tude and  radius  vector,  for  example)  may  have  been  trifling.  But 
in  order  to  obtain  these  small  disturbances,  it  is  necessary  to  pass 
through  the  perturbations  of  the  elements,  which,  relatively,  are 
very  considerable,  and  of  which  the  calculation  is  rendered  laborious 
by  reason  of  the  slow  convergence  of  the  series ;  and  this  incon- 
venience exists  not  merely  in  the  case  of  the  perturbations  of  the 
first  order  with  respect  to  the  masses,  but  in  a  still  greater  degree 
in  the  case  of  those  of  the  second  and  of  the  higher  orders.  For 
these  reasons  the  calculation  of  the  perturbations  has  hitherto 
been  in  some  respects  imperfect  and  unsatisfactory ;  the  computer 
always  finding  himself  obliged  to  omit  a  number  of  the  smaller  terms 
without  having  any  assurance  that  the  error  resulting  from  the  omis- 
sion is  insensible ;  or,  as  M.  Hansen  has  remarked,  rather  from  a 
sort  of  presentiment  that  the  omitted  terms  have  no  appreciable  in- 
fluence, than  from  a  mathematical  demonstration  of  their  influence 
being  insensible. 

It  was  with  a  view  to  remove  these  defects  from  the  lunar  and 
planetary  theories  that  M.  Hansen  undertook  the  series  of  remark- 
able investigations  which  have  appeared  from  time  to  time,  during 
a  considerable  number  of  years  (partly  in  Professor  Schumacher's 
invaluable  Repertory,  the  Astronomische  Nachrichten,  and  partly  in 
two  separate  publications, — one  on  the  perturbations  of  Jupiter  and 
Saturn,  and  the  other  on  the  lunar  theory),  for  which  the  Council  has 
now  awarded  the  Society's  medal.  His  method  of  expressing  the 
perturbations  is  based  on  that  of  Lagrange ;  but  the  modifications 
which  he  has  introduced  are  of  an  important  kind,  and  lead,  in  fact, 


Royal  Astronomical  Society.  525 

to  an  entirely  new  mode  of  conducting  the  numerical  calculations  ; 
so  that,  if  it  cannot  be  said  that  he  has  furnished  us  with  a  new  in- 
strument wherewith  to  attack  the  difficulties  of  the  problem,  he  is 
at  least  entitled  to  the  merit  of  having  taught  us  a  new  method  of 
applying  that  of  which  we  were  already  in  possession. 

On  taking  a  general  view  of  Hansen's  method*,  the  point  which 
first  presents  itself  as  remarkable,  and  that  indeed  in  which  the 
novelty  of  his  process  essentially  consists,  is  the  original  and  highly 
ingenious  artifice  which  he  employs  in  order  to  arrive  at  the  ex- 
pressions for  the  'perturbed  coordinates, — namely,  the  longitude, 
radius  vector,  and  latitude.  In  the  usual  method  of  proceeding,  the 
arbitrary  constants  introduced  by  integration  are  determinate  func- 
tions of  the  elliptic  elements  and  time,  and  the  perturbations  of  co- 
ordinates are  obtained  by  supposing  the  elements  to  vary.  Instead 
of  the  true  time,  M.  Hansen  introduces  into  the  functions  an  ana- 
logous, but  indeterminate  quantity,  and  considers  the  elements  as 
invariable.  He  then  determines  the  variations  which  this  quantity 
must  undergo  (in  other  words,  he  finds  what  alteration  must  be 
made  in  the  time,  in  the  place  where  it  enters  explicitly  into  the 
elliptic  formulae),  in  order  that  the  elliptic  formulae,  with  altered 
time  and  invariable  elements,  may  give  the  same  value  of  the  inde- 
terminate functions  as  would  be  found  by  using  the  true  time  and 
variable  elements.  Suppose,  for  example,  the  function  of  elements 
and  time  to  be  the  true  longitude  ;  then  the  problem,  according  to 
M.  Hansen's  method  of  viewing  it,  amounts  to  this  : — To  find  the 
perturbations  which  must  be  applied  to  the  mean  longitude,  in  order 
that  the  true  longitude  deduced  from  it  with  the  use  of  invariable 
elements,  may  be  the  true  perturbed  longitude. 

It  is  evident,  that  the  use  of  invariable  elements,  and  time  altered 
so  as  to  give  the  correct  value  for  longitude,  would  not,  with  the 
elliptic  formulae,  give  a  correct  value  of  the  radius  vector ;  but  this 
difficulty  is  surmounted  in  an  extremely  ingenious  manner  by  the 
introduction  of  subsidiary  terms,  which,  being  applied  as  corrections 
to  the  radius  vector  of  the  unaltered  elliptic  orbit  {i.  e.  unaltered 
except  in  time),  give  its  true  perturbed  value.  By  similar  considera- 
tions an  expression  is  found  for  the  latitude  in  the  disturbed  orbit. 
It  would  be  impossible,  however,  without  the  aid  of  algebraic  sym- 
bols, to  give  an  idea  of  the  analytical  processes  employed  for  deter- 
mining these  subsidiary  terms ;  and  for  the  same  reason  I  must  con- 
tent myself  with  a  bare  allusion  to  the  still  more  remarkable  artifice 
to  which  he  has  recourse  in  order  to  obtain  an  expression  for  the 
continuous  variation  of  the  perigee  and  node  of  the  lunar  orbit,  for 
which,  by  reason  of  their  rapid  revolution,  invariable  elements  will 
clearly  not  suffice,  and  a  departure  in  some  degree  from  the  original 
principles  becomes  necessary. 

These  deviations  from  the  usual  methods  lead  to  very  important 
advantages  in  the  calculation  of  the  tables,  for  the  series  expressing 
the  perturbations  of  coordinates  are  not  only  rendered  more  conver- 

*  [On  the  subject  of  M.  Hansen's  method  see  Phil.  Mag.,  Third  Series, 
vol.  xix.  p.  82.— Edit.] 


526  Royal  Astronomical  Society. 

gent,  whereby  a  smaller  number  of  terms  is  required  to  be  computed, 
but  the  coefficients  of  the  individual  terms  are  obtained  with  a  smaller 
amount  of  labour  than  was  necessary  in  the  methods  hitherto  em- 
ployed. 

It  will  be  readily  seen  from  whathas  now  been  said,  that  the  general 
aim  of  M.  Hansen's  researches  is  the  improvement  of  the  methods 
of  expressing  the  lunar  and  planetary  perturbations,  so  as  to  render 
the  numerical  calculations  more  easy  and  more  certain.  There  is, 
however,  one  advantage  which  M.  Hansen  states  to  belong  to  his 
method,  of  by  far  too  important  a  kind  to  be  passed  over  without 
particular  notice.  It  is  this  :  —  In  the  series  which  express  the  values 
of  the  disturbed  coordinates,  every  term  exceeding  a  certain  nu- 
merical value,  assumed  at  pleasure,  can  be  immediately  recognised, 
so  that  all  those  terms  which  fall  below  the  assumed  value  may  be 
rejected  from  the  first,  with  the  certainty  that  their  sum  falls  within 
a  given  limit.  The  certainty  thus  acquired  that  every  term  having 
a  sensible  value  is  retained  in  the  calculation,  is  an  improvement 
in  the  theory  on  which  it  would  be  difficult  to  set  too  high  a  value ; 
and  in  fact  it  removes  the  principal  defect  which  has  hitherto  at- 
tended all  the  methods  of  approximation  which  have  been  proposed. 
Nor  is  this  advantage  obtained  by  any  sacrifice  of  generality ;  for 
neither  with  respect  to  the  eccentricity  and  inclination,  nor  powers 
of  the  mass,  is  any  other  restriction  introduced  than  is  inseparable 
from  the  nature  of  the  problem. 

Besides  these  principal  advantages  of  more  rapidly  converging 
series,  and  certainly  with  respect  to  the  value  of  the  omitted  terms, 
there  are  some  minor  advantages  incidental  to  the  new  method, 
which,  however,  are  still  of  great  importance.  Among  these  may 
be  mentioned  certain  relations  subsisting  among  the  analytical  ex- 
pressions of  the  coordinates,  pointed  out  by  M.  Hansen,  from  which 
equations  of  condition  are  deduced  which  not  only  facilitate  the  cal- 
culations but  afford  a  ready  means  of  verification. 

The  applications  which  M.  Hansen  has  as  yet  made  of  his  me- 
thod are  to  the  inequalities  of  Jupiter  and  Saturn*,  in  a  memoir 
which  obtained  the  prize  of  the  Royal  Academy  of  Sciences  of  Berlin ; 
and,  to  the  lunar  theory,  in  a  work  recently  publishedf.  In  the 
former  memoir  the  theory  is  worked  out  to  a  numerical  result.  The 
expressions  for  the  differential  values  of  the  longitude,  latitude,  and 
radius  vector,  are  integrated  by  the  method  of  quadratures,  and  re- 
sults obtained  which  agree  with  those  derived  from  the  ordinary 
methods  of  approximation  founded  on  the  smallness  of  the  eccen- 
tricities and  inclinations.  The  approximations  are,  indeed,  only 
carried  to  terms  of  the  second  order  inclusive,  with  respect  to  the 
masses ;  but  in  the  case  of  Saturn,  all  the  terms  of  this  order  ex- 
ceeding a  certain  numerical  value  are  calculated.     His  theory  of  the 

*  Untersuchung  ubcr  die  gegenseitigcn  Storungen  des  Jupitcrs  und  Saturns. 
Berlin,  1831. 

t  Fundamenta  nova  Investigationis  Orbitcc  vera  quam  Luna  perlustrat. 
Gothse,  1838. 


Royal  Astronomical  Society.  527 

lunar  perturbations,  which  presents  difficulties  of  a  peculiar  kind,  is 
not  so  far  advanced,  and  much  is  still  wanting  to  render  it  complete 
even  as  a  symbolical  theory.  But  in  a  recent  number  of  the  Nach- 
richten*  he  has  announced  that  the  calculations,  on  which  he  has 
been  for  some  time  engaged,  are  now  proceeding  towards  a  conclu- 
sion ;  and  he  has  given  some  results  which  show  that  the  new  me- 
thods apply  with  as  much  advantage  to  the  moon  as  to  the  planets. 

Thus,  gentlemen,  I  have  endeavoured  to  place  before  you  a  sketch 
of  M.  Hansen's  researches,  which,  brief  and  imperfect  as  it  is,  will 
enable  you  to  understand  their  object,  and  appreciate  their  import- 
ance. Should  it  be  thought  that  these  investigations  refer  only  to 
matters  of  detail,  and  that  the  results  at  which  he  has  arrived  in- 
clude none  of  those  grand  discoveries  which  enlarge  the  boundaries 
of  science,  and  give  us,  as  it  were,  a  new  insight  into  the  constitu- 
tion of  the  universe,  let  it  be  remembered  that  the  progress  already 
made  in  physical  astronomy  has  narrowed  the  field  to  the  present 
inquirer,  and  that,  in  proportion  as  science  advances,  its  processes 
become  more  and  more  intricate.  The  problem  of  the  universe,  dif- 
ficult as  it  is,  is  still  a  limited  problem  ;  and  the  successive  steps  in 
its  solution  may  be  assimilated  to  the  terms  of  one  of  those  con- 
verging series  expressing  the  perturbations  we  have  been  speaking 
of,  in  which  each  succeeding  term  is  not  only  smaller  in  value  than 
the  preceding,  but  also  more  difficult  of  calculation.  It  is  with  the 
smaller  terms  only  that  the  theoretical  astronomer  has  now  to  con- 
cern himself ;  but  his  labours,  though  necessarily  attended  with  less 
brilliant  results,  are  not  on  that  account  the  less  necessary  or  useful. 
On  the  contrary,  no  more  valuable  service  remains  to  be  rendered 
to  astronomy,  in  the  present  state  of  the  science,  than  the  improve- 
ment of  the  existing  methods  of  computing  the  lunar  and  planetary 
perturbations.  The  labours  of  M.  Hansen  have  been  steadily,  and 
perseveringly,  and  successfully  directed  to  this  end.  Whether  the 
new  methods  which  he  has  so  ingeniously  developed  will  be  found 
in  all  cases  preferable  to  those  with  which  we  are  already  familiar, 
or  whether  they  will  ultimately  be  adopted  by  astronomers  as  afford- 
ing the  most  convenient  forms  under  which  the  conditions  of  the 
solar  system  can  be  expressed,  is  a  question  which  your  Council  do 
not  venture  to  decide,  and  on  which,  perhaps,  it  would  at  present 
be  premature  to  form  an  opinion.  But  with  respect  to  the  pro- 
found ingenuity  and  consummate  analytical  skill  which  he  has 
brought  to  bear  on  the  intricate  subjects  of  his  investigation,  there 
can  be  but  one  voice.  His  researches,  which  have  been  of  the  most 
laborious  and  abstruse  kind,  have  been  directed  to  the  highest  and 
most  important  questions  of  astronomy ;  and  the  means  by  which 
he  has  sought  to  conquer  the  still  remaining  difficulties,  present 
more  of  novelty  and  originality,  and  afford  stronger  hopes  of  re- 
moving the  differences  which  still  exist  between  the  tables  and  ob- 
servation, than  any  which  have  been  employed  since  the  variation 
of  arbitrary  constants  was  propounded  by  Lagrange.  On  the  whole, 
having  respect  to  the  importance  of  the  subject,  the  results  which 

*  No.  403. 


528  Royal  Astronomical  Society, 

have  already  been  obtained,  and  the  promise  afforded  of  future  im- 
provements, the  Council  doubt  not  that  the  Society,  and  astronomers 
in  general,  will  ratify  its  decision. 

The  President  then,  addressing  the  Foreign  Secretary,  continued  as  fol- 
lows : — 
Mr.  Rothman, — In  transmitting  this  medal  to  Professor  Hansen, 
assure  him  of  the  lively  interest  which  this  Society  takes  in  the  con- 
tinuance of  his  important  labours ;  and  convey  to  him  our  warmest 
wishes  for  his  health  and  happiness,  that  he  maybe  enabled  to  com- 
plete those  improvements  in  the  most  arduous  departments  of  our 
science  which  he  has  so  auspiciously  commenced,  and  thereby  ac- 
quire a  still  stronger  title  to  the  gratitude  of  astronomers,  and  to  a 
place  among  those  who  have  most  signally  contributed  to  the  deve- 
lopment of  the  theory  of  Newton. 

The  Meeting  then  proceeded  to  the  Election  of  the'  Council  for  the 
ensuing  Year,  when  the  following  Fellows  were  elected,  viz. 

President :  the  Right  Hon.  Lord  Wrottesley,  M.A.,  F.R.S. — Vice- 
Presidents  :  Francis  Baily,  Esq.,  F.R.S. ;  Rev.  George  Fisher,  M.A., 
F.R.S. ;  Sir  John  F.  W.  Herschel,  Bart.,  K.H.,  M.A.,  F.R.S. ;  Rev. 
Richard  Sheepshanks,  M.A.,  F.R.S. — Treasure?- :  George  Bishop, 
Esq.— Secretaries :  Rev.  Robert  Main,  M.A. ;  Richard  W.  Roth- 
man, Esq.,  M.A. — Foreign  Secretary :  Thomas  Galloway,  Esq.,  M.A., 
F.R.S— Council:  George  Biddell  Airy,  Esq.,  M.A.,  F.R.S.,  Astro- 
nomer  Royal ;  Rev.  W.  RutterDawes  ;  Augustus  De  Morgan,  Esq.  ; 
Thomas  Jones,  Esq.,  F.R.S. ;  John  Lee,  Esq.,  LL.D.,  F.R.S. ;  Major- 
General  C.  W.  Pasley,  R.E.,  F.R.S. ;  Lieut.  Henry  Raper,  R.N.  ; 
Edward  Riddle,  Esq. ;  Lieut.  William  S.  Stratford,  R.N.,  F.R.S. ; 
Charles  B.  Vignoles,  Esq. 

April  8. — The  following  communications  were  read: — 

I.  On  the  Aggregate  Mass  of  the  Binary  Star  61  Cygni.  By 
S.  M.  Drach,  Esq. 

The  truth  of  universal  gravitation  having  been  confirmed  by  the 
elliptic  form  of  the  orbits  of  binary  stars,  it  follows  that  knowing 
the  absolute  distances  of  the  component  members  and  their  period 
of  revolution  round  each  other,  we  are  able  to  deduce  their  aggre- 
gate mass  compared  with  that  of  our  sun  and  a  planet,  by  exactly 
the  same  process  which  acquaints  us  with  the  various  masses  of  the 
planets  which  are  attended  with  satellites. 

The  ratio  of  the  sums  of  the  masses  of  the  component  bodies  in 
two  such  systems  being  then  that  of  the  cubes  of  the  mean  distances 
of  the  components,  multiplied  into  that  of  the  inverse  squares  of 
their  periods  of  revolution  round  each  other,  we  may  assume  that 
one  system  is  composed  of  the  earth  and  sun,  and  we  have  then 
two  cases  to  consider :  1st,  when  this  binary  star  is  of  very  small 
mass  compared  with  the  sun,  in  which  case  the  system  would  revolve 
about  the  sun,  the  centre  of  gravity  being  near  the  sun's  centre  ; 
and,  2ndly,  when  the  star's  mass  is  much  superior  to  that  of  the 
sun,  in  which  case  the  orbital  motion  of  the  star  would  be  only 


Royal  Astronomical  Society,  529 

apparent,  and  owing  to  the  real  revolution  of  the  solar  system 
round  it. 

Applying  these  remarks  to  the  case  of  the  star  61  Cygni,  and 
assuming  Bessel's  value  of  the  parallax,  and  the  usually  assumed 
elements  of  the  orbit  of  this  binary  system,  it  appears  evident  that 
this  system  is  unconnected  with  the  solar  system.  It  does  not,  how- 
ever, appear  impossible  that  both  systems  revolve  round  a  third  at  an 
immensely  greater  distance  than  that  of  the  sun  from  the  earth. 

The  author,  in  conclusion,  adverts  to  the  great  importance,  in 
the  present  advanced  state  of  practical  astronomy,  of  noting  the  po- 
sitions of  the  stars  having  the  greatest  proper  motions  with  all  pos- 
sible accuracy,  and  of  rigorously  comparing  the  deduced  proper  mo- 
tions at  equal  intervals  of  time,  for  the  purpose  of  discovering  whether 
the  motions  are  performed  in  one  plane,  and  whether  they  are  uni- 
form ;  and  also  to  the  importance  of  having  a  catalogue  of  stars 
accurately  arranged  in  order  of  brilliancy  by  means  of  photometrical 
observations,  as  an  essentially  requisite  element  in  the  determination 
of  their  relative  distances  from  the  earth. 

II.  Second  Note  on  the  Mass  of  Venus.  By  R.  W.  Rothman, 
Esq. 

In  a  Note  on  the  Masses  of  Mercury  and  Venus,  read  at  the  Meet- 
ing of  this  Society  on  the  14th  of  January*,  I  stated  that  a  consi- 
deration of  the  motion  of  the  perihelion  of  Venus  had  led  me  to  con- 
clude, that  it  was  necessary  to  diminish  the  mass  of  Mercury  by  a 

4 
quantity  estimated  approximately  at  —    This  would  make  the  mass 

in  question  ■■        ■     ■.     I  may  observe  in  passing,  that  in  the  notice 
3182843 

of  the  meeting  of  the  14th  of  January,  page  132,  there  is  a  misprint 
in  the  algebraical  formula  for  the  motion  of  the  perihelion ;  but  this 
is  merely  a  typographical  error,  and  the  calculations  are  correct. 
At  the  same  meeting  there  was  read  an  extract  of  a  letter  from  Pro- 
fessor Encke  to  the  Astronomer  Royal,  from  which  it  appears  that 
Professor  Encke,  guided  by  very  different  considerations,  has  been 

led  to  fix  the  mass  of  Mercury  in  the  first  instance  at ,  and 

'  3091947 

subsequently  at 


4865751 

At  the  end  of  my  Note  I  stated  that  the  secular  equations  affect- 
ing the  orbit  of  Mercury  appeared  to  confirm  the  necessity  of  an 
augmentation  of  the  mass  of  Venus,  to  which  I  have  been  led  by 
an  examination  of  the  secular  motion  of  the  node  of  the  latter  planet. 
But,  in  fact,  this  deserves  somewhat  further  development. 

I  have  calculated  the  secular  equation  of  the  node  of  Mercury 
with  the  same  planetary  masses  as  those  assumed  in  my  first 
node,  excepting  that  of  Mercury,  which  I  have  supposed  equal  to 

1 
3182843' 

*  See  present  volume,  p.  398. 
Phil.  Mag.  S.  3.  No.  141.  Suppl.  Vol.  21.  2  N 


530  Royal  Astronomical  Society. 

I  have  used  the  following  values  of  the  greater  axes  which  are 
slightly  different  from  those  employed  before  : — 
$  =    0-38709888 
?   =    0-72333228 

4   =    1- 

<J  =  1-52369210 

%   =  5-20115524 

Tj   =     9-53797320 

$  =  19-18251740 
With  these  data  I  obtain  for  the  annual  sidereal  motion  of  the  node 
of  mercury : — 

d-8>°.    =  -  7"'264        -  0"-0621  ja,0-  3"*8665  p,  -  0"-S915  ft 
at 

-  0-0991  ft  -2-2292  ft  -  0-1129  ft  -0-0022  ft 

If  we  assume  Encke's  second  value  of  the  mass  of  Mercury,  namely 

4865751'  and  suPPose  H,  ft>  ft.  ft.  ft.  each  =  °> 

then  ^ik  =  -7"-242  -  3"'-867  ft. 

Now,  according  to  Lindenau,  the  tropical  motion  of  the  node 
from  1631  to  1802  is  42"'534  annually;  hence,  with  a  precession 
of  50"-21,  the  annual  sidereal  motion  is  7""676, 

...  _  o"-434      =  -  3"-867  ft 
ft  =  +  o"-n. 

With  the  same  data  as  before  I  have  calculated  the  motion  of  the 
perihelion  of  Mercuiy,  for  which  I  find  the  following  expression  : — 

djLo  =  +  5"-44335      +  2"-88796ft  +  0*86099  ft 
dt  r 

+  0"-02881  j*3  +  l"-59026,<*4+  0"-07604ft. 

The  mass  of  Mercury  does  not  enter  into  this  expression.  The 
coefficient  of  ft  is  insensible.  Supposing  now  ft,  ft,  ft,  ft,  each 
=  0, 

^5=  +  5"-44335  +  2"-8876ft. 
a  t 

Now  Lindenau  gives  for  the  tropical  motion  of  the  perihelion 

56"-354 ;  or,  with  a  precession  of  50"-21,  an  annual  sidereal  motion 

=  +6"-144. 

.-.  6"*  144  =  5"-443  +  2"-888  ft 

_  0  -701    _  nv.9, 
•   n,.  =  =  u  -Jo. 

pl        2  -888 
The  node  of  Venus,  as  given  in  my  first  note,  furnishes  us,  as- 
suming Encke's  second  mass  of  Mercury,  and  neglecting  the  terms 
which  contain  ft,  ft,  ft,  ft.  ft.  with  tne  equation 
_  i"-60  =  -  5"- 174  ft 
.-.  ft  =  +  0"'31. 


Royal  Astronomical  Society.  531 

The  three  values  of  /x,  are  then 

p,  =  +o"-n 

jx,  =  +  0  -25 

JM,1  =  +0  '31 
or,  taking  the  mean  /&,  =  0"'22. 

This,  of  course,  is  only  given  as  an  approximate  estimation ;  but 
it  seems  difficult  to  resist  the  conclusion  that  the  mass  of  Venus 
should  be  augmented  by  a  quantity  which  cannot  be  put  lower  than 
one-tenth,  and  is  probably  considerably  larger.     An  augmentation 

of  one-tenth  would  make  this  massogt-0;;o,  of  two-tenths,  -  .. .  0 ., ^ . 

365308  334806 

III.  On  a  Method  of  Determining  the  Latitude  at  Sea.  By  M . 
C.  L.  von  Littrow,  Adjoint- Astronomer  at  the  Imperial  Observatory 
at  Vienna.  Communicated  by  the  Rev.  W.  Whewell,  Master  of 
Trinity  College,  Cambridge. 

IV.  On  the  Rectification  of  Equatoreals  by  Observations  of  Stars 
on  the  Meridian  and  at  an  Hour-Angle  of  Six  Hours.  By  M.  C.  L. 
von  Littrow.     Communicated  by  the  Rev.  W.  Whewell. 

V.  The  Parallax  of  a  Centauri  deduced  from  Mr.  Maclear's  Ob- 
servations at  the  Cape  of  Good  Hope  in  the  years  1839  and  1840. 
By  Professor  Henderson. 

An  abstract  of  the  principal  contents  of  this  paper  will  be  found 
in  Professor  Henderson's  letter,  contained  in  the  last  Monthly  No- 
tice, viz.  that  for  March  1842*.  In  addition,  the  author  gives  the 
following  facts  relating  to  the  history  of  the  observations  of  the 
star  a  Centauri.  The  earliest  recorded  observations  which  he  has 
found  are  those  of  Richer,  at  Cayenne,  in  1673,  and  ofHalley,  at  St. 
Helena,  in  1677  ;  but  neither  of  these  astronomers  mentions  it  as 
being  double.  Feuillee  appears  to  have  been  the  first  person  who 
observed  it  to  be  double,  his  observations  being  made  at  Conception, 
in  Chili,  in  July  1709,  with  a  telescope  of  18  feet  focal  length.  He 
estimates  their  magnitudes  as  being  of  the  third  and  fourth,  the 
smaller  star  being  the  more  westerly,  and  their  distance  as  equal  to 
the  apparent  diameter  of  the  smaller  star  {Journal  des  Observations 
Physiques,  &c,  par  Louis  Feuillee,  tome  i.  p.  425  ;  Paris,  1714). 

La  Condamine  observed  the  star  during  the  expedition  to  Peru 
for  measuring  an  arc  of  the  meridian  (see  Philosophical  Transactions 
for  1 749,  p.  142).  He  estimated  it  as  being  of  the  first  magnitude, 
and  recognised  its  duplicity ;  and  he  remarked  that  the  larger  star 
was  northward  of  the  other,  and  to  the  east  of  it.  From  La  Caille's 
observations  in  1751-2,  the  distance  of  the  two  stars  appears  to 
have  been  22"*5.  Maskelyne  observed  them  at  St.  Helena  in  1761 
(see  Philosophical  Transactions  for  1764,  p.  383),  and  estimated 
them  as  being  of  the  second  and  fourth  magnitudes.  Their  distance, 
as  observed  with  a  divided  object-glass  micrometer,  he  found  to  be 
from  15"  to  16".  From  this  time  to  the  time  of  the  institution  of 
the  Paramatta  Observatory,  the  author  has  met  with  no  observations 
of  the  distance  of  the  stars.     Mr.  Dunlop,  in  the  years  1 825-6,  found 

*  See  present  volume,  p.  482. 

2N2 


532  Royal  Irish  Academy. 

the  distance  to  be  23"  (see  Memoirs  of  the  Royal  Astronomical  So- 
ciety, vol.  iii.  p.  265),  since  which  time  it  has  been  decreasing  at  the 
rate  of  more  than  half  a  second  per  annum.  The  angle  of  position 
scarcely  appears  to  have  changed  since  the  time  of  La  Caille  ;  whence 
it  may  be  inferred  that  the  relative  orbit  is  seen  projected  into  a 
straight  line,  or  a  very  eccentric  ellipse  ;  that  an  apparent  maximum 
of  distance  was  attained  in  the  end  of  the  last  or  the  beginning  of 
the  present  century ;  and  that,  about  twenty  years  hence,  the  stars 
will  probably  be  seen  very  near  each  other,  or  in  apparent  contact ; 
but  the  data  are  at  present  insufficient  to  give  even  an  approxima- 
tion to  the  major  axis  of  the  orbit  and  time  of  revolution. 

VI.  Observations  of  the  beginning  and  end  of  the  Solar  Eclipse 
of  July  18,  1841.  By  Dr.  Cruikshank.  Communicated  by  G. 
Innes,  Esq. 

The  eclipse  was  observed  at  Fyvie  Castle,  in  latitude  57°  26'  40'/-7 
north,  and  longitude  9m  32s*  6  west,  where  there  is  a  good  clock  by 
Hardy  and  a  fine  transit  instrument.  The  magnifying  power  of  the 
telescope  used  was  about  thirty. 

h    m       8  s 

Time  of  the  beginning  of  the  eclipse.    2  15     4 ;  uncertain  to  10 
Time  of  the  end 2  57  30         2. 


ROYAL  IRISH  ACADEMY. 

[Continued  from  p.  397.] 

May  24, 1841  (Continued) .—The  Rev.  Charles  Graves,  F.T.C.D., 
read  a  paper  "  On  the  Application  of  Analysis  to  spherical  Geo- 
metry." 

The  object  of  this  paper  is  to  investigate  and  apply  to  the  geo- 
metry of  the  sphere,  a  method  strictly  analogous  to  that  of  rectilinear 
coordinates  employed  in  plane  geometry. 

Through  a  point  O  on  the  surface  of  the  sphere,  which  is  called 
the  origin,  let  two  fixed  quadrantal  arcs  of  great  circles  O  X,  O  Y 
be  drawn ;  then  if  arcs  be  drawn  from  Y  and  X  through  any  point 
P  on  the  sphere,  and  respectively  meeting  O  X  and  O  Y  in  M  and 
N,  the  trigonometric  tangents  of  the  arcs  O  M,  ON  are  to  be  con- 
sidered as  the  coordinates  of  the  point  P,  and  denoted  by  x  and  y. 
The  fixed  arcs  may  be  called  arcs  of  reference.  An  equation  of  the 
first  degree  between  x  and  y  represents  a  great  circle ;  an  equation 
of  the  second  degree,  a  spherical  conic  ;  and,  in  general,  an  equation 
of  the  nth  degree,  between  the  spherical  coordinates  x  and  y,  repre- 
sents a  curve  formed  by  the  intersection  of  the  sphere  with  a  cone 
of  the  rath  degree,  having  its  vertex  at  the  centre  of  the  sphere. 

Though  it  is  not  easy  to  establish  the  general  formulae  for  the 
transformation  of  spherical  coordinates,  they  are  found  to  be  simple. 

Let  x  and  y  be  the  coordinates  of  a  point  referred  to  two  given 

arcs,  and  let  x',  y'  be  the  coordinates  of  the  same  point  referred  to 

two  new  arcs,  whose  equations  as  referred  to  the  given  arcs  are 

y  —  y"  =  m(x  —  x"), 

y  —  y"  =  m'  (x  —  x'1), 

x",  y"  being  the  coordinates  of  the  new  origin ;  then  the  values  of 


Royal  Irish  Academy.  533 

x  and  y  to  be  used  in  the  transformation  of  coordinates  would  be 

_x"(ax'  +  by'  -  1) 

x — - — , 

px'  +  qy'  —  1 

y"(cx'  +  dy'-l) 

px1  +  qy'  —  1 

In  which  a,  b,  c,  d,  p,  and  q  are  functions  of  m,  m',  x",  and  y".     It 

is  evident  that  the  degree  of  the  transformed  equation  in  x',  y',  will 

be  the  same  as  that  of  the  original  one  in  x  and  y. 

The  great  circle  represented  by  the  equation 
a  x  +  /3  y  =  1 , 
meets  the  arcs  of  reference  in  two  points,  the  cotangents  of  whose 
distances  from  the  origin  are  a  and  /3  ;  and,  if  the  arcs  of  reference 
meet  at  right  angles,  the  coordinates  of  the  pole  of  this  great  circle 
are  —  a,  and  —  /3.  It  appears  from  this,  that  if  a  and  /3,  instead  of 
being  fixed,  are  connected  by  an  equation  of  the  first  degree,  the 
great  circle  will  turn  round  a  fixed  point.  And,  in  general,  if  a  and 
/3  be  connected  by  an  equation  of  the  rath  degree,  the  great  circle 
will  envelope  a  spherical  curve  to  which  n  tangent  arcs  may  be 
drawn  from  the  same  point.  Thus,  the  fundamental  principles  of  the 
theory  of  polar  reciprocals  present  themselves  to  us  in  the  most  ob- 
vious manner  as  we  enter  upon  the  analytic  geometry  of  the  sphere. 

A  spherical  curve  being  represented  by  an  equation  between  rec- 
tangular coordinates,  the  equation  of  the  great  circle  touching  it  at 
the  point  x' ,  y' ,  is 

(y  —  y')  dx'  —  (x  —  x')  d  y'  =  0 ; 
the  equation  of  the  normal  arc  at  the  same  point  is 
(y  ~  V1)  [d  y'  +  x'  0'  dy'  -y'd  #')] 
+  (x  -  x')  [dx'  +  y'  (y'dx'  -  x'  dy')~]  =  0. 
Now,  if  we  differentiate  this  last  equation  with  respect  to  x'  and  y' , 
supposing  x  and  y  to  be  constant,  we  should  find  another  equation, 
which,  taken  along  with  that  of  the  normal  arc,  would  furnish  the 
values  of  x  and  y,  the  coordinates  of  the  point  in  which  two  con- 
secutive normal  arcs  intersect :  and  thus,  as  in  plane  geometry,  we 
find  the  evolute  of  a  spherical  curve. 

Let  2  y  be  the  diametral  arc  of  the  circle  of  the  sphere  which 
osculates  a  spherical  curve  at  the  point  x\  y',  Mr.  Graves  finds  that 

tan  7  =  ±     ldx^  +  dy^  +  (x'dy'-y'dx')^ 
~  (1  +  xh2  +  y'~)i'  (dx'  d2  y'  —  dy'  d2x') 
For  the  rectification  and  quadrature  of  a  spherical  curve  given  by 
an  equation  between  rectangular  coordinates,  the  following  formulae 
arc  to  be  employed  : — 

d    _  "/dx7'2  +  dy'12  +  (*'  dy'  -  y'  d xj- 

1  S~  1  +  x'2  +  y'2 

y  dx 

and  d  (area)  = — 77-        a    — -. 

v       '       (1  +  x2)  Vl  +  x2  +  tf2 

In  the  preceding  equations  the  radius  of  the  sphere  has  been  sup- 
posed =  1 . 


534?  Royal  Irish  Academy. 

The  method  of  coordinates  here  employed  by  Mr.  Graves  is  entirely 
distinct  from  that  which  is  developed  by  Mr.  Davies  in  a  paper  in 
the  12th  vol.  of  the  Transactions  of  the  Royal  Society  of  Edinburgh. 
Mr.  Graves  apprehends,  however,  that  he  has  been  anticipated  in  the 
choice  of  these  coordinates  by  M.  Gudermann  of  Cleves,  who  is  the 
author  of  an  "  Outline  of  Analytic  Spherics,"  which  Mr.  Graves 
has  been  unable  to  procure. 

The  President  communicated  a  new  demonstration  of  Fourier's 
theorem. 

A  letter  was  read  from  Professor  Holmboe,  accompanying  his  me- 
moir, De  Prised  Re  Monetarid  Norvegia,  &c,  and  requesting  to  know 
from  the  Academy  whether  any  of  the  coins  described  in  that  work 
are  found  in  Ireland*. 

July  12f. — Part  I.  of  a  "  Memoir  on  the  Dialytic  Method  of  Eli- 
mination," by  J.  J.  Sylvester,  Esq.,  A.M.,  of  Trinity  College,  Dublin, 
and  Professor  of  Natural  Philosophy  in  University  College,  London, 
was  read. 

The  author  confines  himself  in  this  part  to  the  treatment  of  two 
equations,  the  final  and  other  derivees  of  which  form  the  subject  of 
investigation. 

The  author  was  led  to  reconsider  his  former  labours  in  this  de- 
partment of  the  general  theory  by  finding  certain  results  announced 
by  M.  Cauchy  in  L'Institut,  March  Number  of  the  present  year, 
which  flow  as  obvious  and  immediate  consequences  from  Mr.  Syl- 
vester's own  previously  published  principles  and  method. 

Let  there  be  two  equations  in  x, 

U  =  a  xn  +  b  x11-1  +  c  xn~2  +  e  xn~3  +  &c.  =  0, 

V=axw+|3/-1  +  X^-2  +  &c.  =0, 

and  let  n  =  m  +  i,  where  ;  is  zero  or  any  positive  value  (as  may  be). 
Let  any  such  quantities  as  xr  U,  xe  V,  be  termed  augmentatives 
of  U  or  V. 

To  obtain  the  derivee  of  a  degree  s  units  lower  than  V,  we  must 
join  s  augmentatives  of  U  with  s  -f  <  of  V.  Then  out  of  2  s-)-  i 
equations 

x°  .  U  =  0,    x\  .  U  =  0,     *2 .  U  =  0, Xs-1 .  U  =  0, 

x°.V  =  0,    x>.V  =  0,    *°-.V  =  0, ^+*-1.v  =  o, 

we  may  eliminate  linearly  2  s  -f-  i  —  1  quantities. 

Now  these  equations  contain  no  power  of  x  higher  than 
m  _j_  i  _j.  5  —  1 ;  accordingly,  all  powers  of  x,  superior  torn  —  s,  may 
be  eliminated,  and  the  derivee  of  the  degree  (m  —  s)  obtained  in  its 
prime  form. 

Thus  to  obtain  the  final  derivee  (which  is  the  derivee  of  the  de- 
gree zero),  we  take  m  augmentatives  of  U  with  n  of  V,  and  elimi- 
nate (m  +  n  —  1)  quantities,  namely, 

x,  x2,  x*, up  to  xm+n~1. 

*  The  Committee  of  Antiquities,  having  been  consulted  on  this  point, 
reported  in  the  negative. 

[f  An  abstract  of  Prof.  Lloyd's  paper  read  on  June  14th,  will  be  found 
in  the  present  volume,  p.  395.] 


Royal  Irish  Academy.  535 

This  process,  founded  upon  the  dialytic  principle,  admits  of  a  very 
simple  modification.     Let  us  begin  with  the  case  where  » =  0,  or 
m  =  n.     Let  the  augmentatives  of  U  be  termed  U0,  Up  U2  U3, .... 
and  of  V,  V0,  V„  V„,  V3, ....  the  equation  themselves  being  written 

\J  =  axn  +  bxn-1  +  cxn~2  +  &c. 

V  =  a'xn  +  b'xn~l  +  c'x"-2  +  &c. 

It  will  readily  be  seen  that 

a' .  U0  —  a .  V0, 

(i'U0-*V0)  +  (a'U1-aV1), 

(c'.U0-c.V0)  +  (J'Ul-6VI)  +  («'Us-aVi),&c. 

will  be  each  linearly  independent  functions  of  x,  x%, xm~l,  no 

higher  power  of  x  remaining.  Whence  it  follows,  that  to  obtain  a 
derivee  of  the  degree  (m  —  s)  in  its  prime  form,  we  have  only  to 
employ  the  s  of  those  which  occur  first  in  order,  and  amongst  them 
eliminate  xm~~l,  xm~2, . . . .  xm~~ *+*.  Thus,  to  obtain  the  final  de- 
rivee, we  must  make  use  of  n,  that  is,  the  entire  number  of  them. 

Now,  let  us  suppose  that  i  is  not  zero,  but  m  =  n  —  i.  The 
equation  V  may  be  conceived  to  be  of  n  instead  of  m  dimensions,  if 
we  write  it  under  the  form 

0  .  xn  +  0 .  xn~l  +  0  .  **-*  + +  0  ,  xm+1 

+  axm  +  (3x™-l  +  8ic.  =  0. 

and  we  are  able  to  apply  the  same  method  as  above ;  but  as  the  first 
/  of  the  coefficients  in  the  equation  above  written  are  zero,  the  first 
i  of  the  quantities 

(a'  V0-a  V0),  (b>  U0  -  b  V0)  +  («'  U,  -  a  V,),  &c. 
may  be  read  simply 

-  a  .  V0,     -J.V0-oV„     -  c  V0  -  6  V,  -  a  V2,  &c. 

and  evidently  their  office  can  be  supplied  by  the  simple  augmenta- 
tives themselves, 

V0  =  0,      V,=0,      V9  =  0....  ^  =  0; 

and  thus  <  letters,  which  otherwise  would  be  irrelevant,  fall  out  of 
the  several  derivees. 

The  author  then  proceeds  with  remarks  upon  the  general  theory 
of  simple  equations,  and  shows  how  by  virtue  of  that  theory  his  me- 
thod contains  a  solution  of  the  identity 

Xr.U  +  Yr.V  =  Dr; 
where  Dr  is  a  derivee  of  the  rth  degree  of  U  and  V,  and  accordingly, 
Xr  of  the  form 

X  +  px  +  vx-  + +  flaB»-r-1, 

and  Yr  of  the  form 

I  +  mx  +  ..  ..  +  txn~r-1, 
and  accounts  a  priori  for  the  fact  of  not  more  than  (»  —  r)  simple 
equations  being  required  for  the  determination  of  the  (m  -f-  n  —  2  r) 
quantities  A,  p,  v,  &c.  /,  m,  n,  &c,  by  exhibiting  these  latter  as  known 


536  Royal  Irish  Academy. 

linear  functions  of  no  more  than  (n  —  r)  unknown  quantities  left  to 
be  determined. 

.  Upon  this  remarkable  relation  may  be  constructed  a  method  well 
adapted  for  the  expeditious  computation  of  numerical  values  of  the 
different  derivees. 

He  next,  as  a  point  of  curiosity,  exhibits  the  values  of  the  secon- 
dary functions, 

a' .  U0  —  a  V0, 

b'  .V0-bV0  +  n'.U1-aV„ 

c' .  U0  -  c  .  V0  +  b' .  U,  -  b  V,  +  a' .  U2  -  a  V2>  &c. 

under  the  form  of  symmetric  functions  of  the  roots  of  the  equations 
U  =  0,  V  =  0,  by  aid  of  the  theorems  developed  in  the  London 
and  Edinburgh  Philosophical  Magazine,  December  1839,  and  after- 
wards proceeds  to  a  more  close  examination  of  the  final  derivee  re- 
sulting from  two  equations  each  of  the  same  (any  given)  degree. 

He  conceives  a  number  of  cubic  blocks  each  of  which  has  two 
numbers,  termed  its  characteristics,  inscribed  upon  one  of  its  faces, 
upon  which  the  value  of  such  a  block  (itself  called  an  element)  de- 
pends. 

For  instance,  the  value  of  the  element,  whose  characteristics  are  r, 
s,  is  the  difference  between  two  products :  the  one  of  the  coefficient 
rth  in  order  occurring  in  the  polynomial  U,  by  that  which  comes  sth 
in  order  in  V ;  the  other  product  is  that  of  the  coefficient  sth.  in 
order  of  the  polynomial  V,  by  that  rth  in  order  of  U ;  so  that  if  the 

degree  of  each  equation  be  n,  there  will  be  altogether  i — — — I  such 

m 

elements. 

The  blocks  are  formed  into  squares  or  flats  {plafonds)  of  which 

the  number  is  —  or  — — — ,  according  as  n  is  even  or  odd.     The  first 

of  these  contains  n  blanks  in  a  side,  the  next  (n  —  2),  the  next 
(n  —  4),  till  finally  we  reach  a  square  of  four  blocks  or  of  one,  ac- 
cording as  n  is  even  or  odd.  These  flats  are  laid  upon  one  another , 
so  as  to  form  a  regularly  ascending  pyramid,  of  which  the  two  dia- 
gonal planes  are  termed  the  planes  of  separation  and  symmetry  re- 
spectively. The  former  divides  the  pyramid  into  two  halves,  such 
that  no  element  on  the  one  side  of  it  is  the  same  as  that  of  any 
block  in  the  other.  The  plane  of  symmetry,  as  the  name  denotes, 
divides  the  pyramid  into  two  exactly  similar  parts ;  it  being  a  rule, 
that  all  elements  lying  in  any  given  line  of  a  square  {plafond)  parallel 
to  the  plane  of  separation  are  identical;  moreover,  the  sum  of  the 
characteristics  is  the  same,  for  all  elements  lying  anywhere  in  a  plane 
parallel  to  that  of  separation. 

All  the  terms  in  the  final  derivee  are  made  up  by  multiplying 
n  elements  of  the  pile  together,  under  the  sole  restriction,  that  no 
two  or  more  terms  of  the  said  product  shall  lie  in  any  one  plane  out 
of  the  two  sets  of  planes  perpendicular  to  the  sides  of  the  squares. 
The  sign  of  any  such  product  is  determined  by  the  places  of  either 
set  of  planes  parallel  to  a  side  of  the  squares  and  to  one  another,  in 
which  the  elements  composing  it  may  be  conceived  to  lie. 


lloyal  Irish  Academy. 


537 


The  author  then  enters  into  a  disquisition  relating  to  the  number 
of  terras  which  will  appear  in  the  final  derivee,  and  concludes  this 
first  part  with  the  statement  of  two  general  canons,  each  of  which 
affords  as  many  tests  for  determining  whether  a  prepared  combina- 
tion of  coefficients  can  enter  into  the  final  derivee  of  any  number  of 
equations  as  there  are  units  in  that  number,  but  so  connected  as 
together  only  to  afford  double  that  number,  less  one  of  independent 
conditions. 

The  first  of  these  canons  refers  simply  to  the  number  of  letters 
drawn  out  of  each  of  the  given  equations  (supposed  homogeneous)  ; 
the  second  to  what  he  proposes  to  call  the  weight  of  every  term  in 
the  derivee  in  respect  to  each  of  the  variables  which  are  to  be  elimi- 
nated. 

The  author  subjoins,  for  the  purpose  of  conveying  a  more  accurate 
conception  of  his  Pyramid  of  derivation,  examples  of  the  mode  in 
which  it  is  constructed. 


When  n  =  1  there  is  one  flat, 
viz. 


When  n  =  2  there  is  one  flat, 
viz. 


1,2 


2,  3 

2,  4 

2,  4 

3,4 

Let  n  as  3,  there  will  be  two 
flats: 


Let  n  =  4,  there  will  still  be 
two  flats  only : 


2,  3 

2,4 

2,  4 

3,4 

1,2 

1,3 

1,4 

1,3 

1,4 

2,  4 

1,4 

2,  4 

3,4 

1,2 

1,3 

1,4 

1,5 

1,3 

1,4 

1,5 

2,5 

1,4 

1,5 

2,  5 

3,  5 

1,5 

2,  5 

3,  5 

4,5 

538  Royal  Irish  Academy. 

Let  n  =  5,  there  will  be  three  flats  : 


3,4 


2,  3 

2,  4 

2,  5 

2,  4 

2,5 

3,5 

2,  5 

3,  5 

4,5 

1,2 

1,3 

1,4 

1,5 

1,6 

1,3 

1,4 

1,5 

1,6 

2,6 

1,4 

1,5 

1,6 

2,6 

3,6 

1,5 

1,6 

2,6 

3,6 

4,6 

1,6 

2,6 

3,6 

4,6 

5,6 

Royal  Irish  Academy, 
Let  n  =  6,  there  will  be  three  flats : 


539 


3,4 

3,5 

3,5 

4,5 

2,3 

2,4 

2,5 

2,6 

2,4 

2,5 

2,6 

3,6 

2,5 

2,6 

3,6 

4,6 

2,6 

3,6 

4;  6 

5,6 

1,2 

1,3 

1,4 

1,5 

1,6 

1,7 

1,3 

1,4 

1,5 

1,6 

1,7 

2,7 

1,4 

1,5 

1,6 

1,7 

2,7 

3,7 

1,5 

1,6 

1,7 

2,7 

3,7 

4,7 

1,6 

1,7 

2,7 

3,7 

4,7 

5,7 

1,7 

2,7 

3,7 

4,7 

5,7 

6,7 

Thus  the  work  of  computation  reduces  itself  merely  to  calculating 
n  .  — — —  elements,  or  the  n  (n  +  1)  cross-products  out  of  which 

they  are  constituted,  and  combining  them  factorially  after  that  law 
of  the  pyramid,  to  which  allusion  has  been  already  made. 


540  Geological  Society :  Mr.  Strickland 

GEOLOGICAL  SOCIETY. 

[Continued  from  p.  378.] 

Dec.  15,  A  paper  "On  the  Glacia- diluvial  Phenomena  in  Snow- 
1841.  -^*-  donia  and  the  adjacent  parts  of  North  Wales,"  by 
the  Rev.  Prof.  Buckland,  D.D.,  F.G.S.,  &c.  was  first  read. 

A  paper  was  afterwards  read,  "  On  the  occurrence  of  the  Bristol 
Bone-Bed  in  the  Lower  Lias  near  Tewkesbury,"  by  Hugh  Edwin 
Strickland,  Esq.,  F.G.S. 

After  alluding  to  the  occurrence  of  the  bone-bed  at  various  places 
between  Westbury  and  Watchett,  also  at  Golden  Cliff  and  St.  Hilaiy 
in  Glamorganshire,  and  at  Axmouth,  Mr.  Strickland  proceeds  to 
describe  its  characters  at  three  newly-discovered  localities,  many 
miles  to  the  north  of  the  points  previously  known,  namely,  Coomb 
Hill,  between  Tewkesbury  and  Gloucester,  Wainlode  Cliff,  and 
Bushley. 

1.  Coomb  Hill,  four  miles  south  of  Teiokesbury* . — In  lowering  the 
road  through  the  lias  escarpment  during  the  summer  of  1841  a  con- 
siderable surface  of  the  bone-bed  was  exposed,  and  its  contents  were 
rescued  from  destruction  by  Mr.  Dudfield  of  Tewkesbury.  The  fol- 
lowing section  is  given  by  Mr.  Strickland  : —  Ft.    in. 

1 .  Yellow  clay 2       0 

2.  Lias  limestone 0       3 

3.  Yellow  clay 5       0 

4.  Nodules  of  lias  limestone 0       6 

5.  Brown  clay   14       0 

6.  Impure  pyritic  limestone  with  Pectens  and 

small  bivalves 0  6 

7.  Black  laminated  clay    8  0 

8.  Hard,  grey  pyritic  limestone    0  2 

9.  Black  laminated  clay 1  0 

10.  Greyish  sandstone    0  2 

1 1 .  Black  laminated  clay    1  6 

12.  Bone-bed   0  1 

13.  Black  laminated  clay    3  6 

14.  Compact,  angular,  greenish  marl 25  0 

15.  Red  marl 3  0 

Dip  about  12°  east.  64       8 

The  bone-bed,  No.  12,  rarely  exceeds  one  inch  in  thickness,  and 
frequently  thins  out  to  less  than  a  quarter  of  an  inch.  It  consists  in 
some  places  chiefly  of  scales,  teeth  and  bones  of  fishes,  and  small 
coprolites  cemented  by  iron  pyrites,  but  in  others  the  organic  re- 
mains are  rare,  and  are  replaced  by  a  whitish  micaceous  sandstone. 
The  osseous  fragments,  Mr.  Strickland  states,  have  the  appearance 
of  having  been  washed  into  the  hollows  of  a  rippled  surface  of  clay, 

*  Mr.  Murchison  has  noticed  the  section  formerly  exposed  in  this 
escarpment,  but  at  the  time  he  examined  the  district,  Mr.  Strickland  says, 
the  banks  were  obscured  by  dehris,  and  the  bone-bed  did  not  attract  his 
attention.  See  Mr.  Murchison's  Account  of  the  Geology  of  Cheltenham, 
p.  24,  plate,  fig.  1,  and  Silurian  System,  pp.  20,  29,  pi.  29,  fig.  1. 


on  the  Bone-bed  in  the  Lias  near  Texvlcesbury.        541 

and  of  having  been  subjected  to  slight  mechanical  action.  The  ex- 
istence of  gentle  currents  is  further  proved,  he  says,  by  the  presence 
of  small  rounded  pebbles  of  white  quartz,  a  substance  of  very  rare 
occurrence  in  the  liassic  series.  The  only  shell  found  in  the  bed  at 
Coomb  Hill  is  a  smooth  bivalve,  but  too  imperfect  to  be  generically 
determined. 

2.  Wainlode  Cliff,  three  miles  west -south-west  from  Coomb  Hill. — 
The  section  exposed  at  this  locality  has  been  laid  open  by  the  action 
of  the  Severn,  and  consists  of  the  following  beds  : — 

Ft.    in. 

1 .  Black  laminated  clay,  inclosing,  near  the  top,  a 

band  of  lias  limestone  with  Ostrese    22       0 

2.  Slaty  calcareous   sandstone,  with  a  peculiar 

small  species  of  Pecten   0  4 

3.  Black  laminated  clay 9  0 

4.  Bone-bed,  passing  into  white  sandstone 0  3 

5.  Black  laminated  clay 2  0 

6.  Light  green  angular  marl 23  0 

7.  Red  marls,  with  zones  of  a  greenish  colour  . .  42  0 

Dip  very  slight  to  the  south.  98       7 

The  bone-bed  is  far  less  rich  in  organic  remains,  accumulations  of 
fragments  of  bones  and  coprolites  occurring  at  rare  intervals ;  and 
its  prevailing  character  is  that  of  a  fissile,  white,  micaceous  sand- 
stone, sometimes  acquiring  a  flinty  hardness.  The  upper  surface  of 
the  bed  is  ripple-marked,  and  in  some  cases  presents  impressions 
considered  by  Mr.  Strickland  to  have  been  probably  made  by  the 
claws  of  Crustacea.  A  small  bivalve  is  also  the  only  shell  found  in 
the  bed.  The  stratum  No.  2,  the  author  says,  is  evidently  a  con- 
tinuation of  No.  6.  of  the  Coomb  Hill  section. 

3.  Bushley,  two  miles  and  a  half  west  of  Tewkesbury. — The  inter- 
section of  the  lias  escarpment  by  the  Ledbury  road  near  Bushley 
afforded  Mr.  Strickland  the  following  section  : —  Ft.     in. 

1 .  Black  laminated  clay,  about 10  0 

2.  Lias  limestone    0  4 

3.  Black  laminated  clay ! 6  0 

4.  Compact  slaty  bed  with  numerous  small  bi- 

valves,  and  the   Pecten  of  Wainlode  and 
Coomb  Hill 0       3 

5.  Black  laminated  clay 9       0 

6.  White  micaceous  sandstone,  with  impressions 

of  two  species  of  bivalve  shells 1  0 

7.  Black  laminated  clay 2  6 

8.  Greenish  marl,  about 20  0 

9.  Red  marl '. —  - 

Dip  about  8°  east.  49       1 

The  sandstone  bed,  No.  6,  agreeing  precisely  with  that  at  Wain- 
lode Cliff,  Mr.  Strickland  does  not  hesitate  to  consider  it  the  repre- 
sentative of  the  bone-bed,  though  organic  remains  are  wanting ;  and 
he  points  out  the  identity  of  the  stratum  No.  4.  with  the  beds  Nos. 


542     Geological  Society :  Dr.  E.  Moore  on  Fossil  Bones 

2.  and  6.  of  the  preceding  sections.  The  author  also  refers  to  the 
railway  section  near  Droitwich*,  and  identifies  with  the  bone-bed  the 
two-feet  band  of  white  micaceous  sandstone  six  feet  above  the  top 
of  the  green  marl,  as  it  contains  the  same  indeterminable  small 
bivalve.  He  has  also  examined  sections  of  the  lias  escarpment  at 
Norton  near  Kempsey,  and  Cracombe  Hill  near  Evesham,  and  has 
invariably  detected,  a  few  feet  above  the.  base  of  the  lias  clay,  a 
thin  band  of  white  sandstone  containing  the  same  shell. 

The  bone-bed  at  Axmouth,  Watchett,  Aust,  Westbury,  and  other 
southern  localities,  occupies  precisely  the  same  geological  position, 
or  a  few  feet  above  the  top  of  the  greenish  marls  which  terminate 
the  New  Red  system,  though  much  more  rich  in  organic  remains  ; 
and  Mr.  Strickland  draws  attention  to  this  remarkable  instance  of  a 
very  thin  stratum  ranging  over  a  distance  of  about  112  miles. 

The  great  abundance  of  fossils  in  some  parts  of  this  stratum  the 
author  considers  an  indication  that  a  much  longer  period  probably 
elapsed  during  its  deposition,  either  on  account  of  the  clearness  of 
the  water  or  of  a  gentle  current  which  prevented  the  precipitation  of 
muddy  particles,  than  while  an  equal  thickness  of  the  less  fossiliferous 
clays  above  or  below  it  was  accumulated. 

The  list  of  organic  remains  given  in  the  paper  includes  scales 
of  Gyrolepis  tenuistriatus  ?  and  Amblyurus  ;  teeth  of  Saurichthys  api- 
calis,  Acrodus  minimus,  Hybodus  minor,  Pycnodus  ? ;  others  bearing 
an  analogy  to  those  of  Sargus  ;  portion  of  a  tooth  with  two  finely 
serrated  edges,  and  considered  as  probably  belonging  to  a  saurian 
allied  to  the  genus  Palceosaurus ;  a  tooth  of  Hybodus  De  la  Bechei 
(i?.  medius,  Ag.),  a  ray  of  Nemacanthus  monilifer ;  small  vertebra 
of  a  fish ;  bones  of  an  Ichthyosaurus ;  coprolites ;  and  the  casts  of  the 
bivalve  before  mentioned. 

Mr.  Strickland  next  alludes  to  Sir  Philip  Egerton's  paper  on  the 
Ichthyolites  of  the  bone-bed  f,  and  he  states  that  the  bed  cannot 
be  of  the  age  of  the  muschelkalk,  as  it  overlies  the  red  and  green 
marls,  which  he  considers  to  have  been  satisfactorily  shown  to 
be  equivalent  to  the  Keuper  sandstein  of  Germany ;  and  that 
the  occurrence  of  muschelkalk  fishes  associated  with  lias  Ichthy- 
olites only  justifies  the  inference  that  certain  species  survived  from 
the  period  of  the  muschelkalk  to  that  of  the  bone-bed.  There 
are  yet  stronger  grounds,  Mr.  Strickland  states,  for  placing  the 
bone-bed  in  the  liassic  series  in  the  remarkable  change  a  few  feet 
below  it,  from  black  laminated  clay  to  compact  "  angular "  marl, 
greenish  in  the  upper  part  and  red  below ;  and  he  adds,  the  trans- 
ition is  so  sudden  that  it  may  be  defined  within  the  eighth  of  an 
inch ;  moreover  no  marl  occurs  above  the  line  nor  black  laminated 
clay  below  it ;  and  although,  in  the  case  of  the  bone  bed,  an  arena- 
ceous deposit  similar  to  the  Keuper  sandstein  is  repeated,  accom- 
panied by  some  triassic  organic  remains,  yet,  the  author  adds,  this 
does  not  invalidate  the  evidence  of  the  commencement  of  a  new 
order  of  things,  or  of  an  interesting  passage  into  the  liassic  series 
from  the  triassic  system. 

[*  Phil.  Mag.  S.  3.,  vol.  xviil,  p.  523.]  [f  lb.  vol.  xix.,  p.  522.] 


on  the  surface  of  a  raised  Beach  near  Plymouth.      543 

Lastly,  Mr.  Strickland  notices  the  occurrence  of  precisely  analo- 
gous bone-beds  in  the  Upper  Ludlow  rock,  described  by  Mr.  Mur- 
chison  in  the  '  Silurian  System'  (p.  198),  and  in  Caldy  Island,  near 
the  junction  of  the  carboniferous  limestone  with  the  old  red  sand- 
stone ;  and  he  offers  some  remarks  on  the  bone-beds  being  found  in 
all  the  three  cases  near  the  passage  from  one  great  geological  system 
of  rocks  to  another. 

January  5,  1842. — "  A  Notice  on  the  Fossil  Bones  found  on  the 
surface  of  a  raised  Beach  at  the  Hoe  near  Plymouth,"  by  Edward 
Moore,  M.D.,  F.L.S.,  was.  first  read. 

At  the  Meeting  of  the  British  Association  at  Plymouth,  Dr. 
Moore  read  a  paper  on  the  same  subject  as  that  which  forms  part  of 
the  present  communication*.  In  this  notice  he  first  alludes  to  the 
discovery  of  the  beach  by  the  Rev.  R.  Hennah  in  1827f,  and  to 
Mr.  De  la  Beche's  account  of  numerous  anciently  raised  beaches  in 
Devon  and  Cornwall  J ;  he  then  briefly  describes  the  characters  of 
the  beach,  its  position  in  a  hollow  in  the  limestone  rock,  100  feet 
wide,  70  feet  deep,  and,  at  its  base,  35  feet  above  the  present  high 
water  mark.  He  also  notices  a  projecting  ledge  of  limestone  stretching 
several  hundred  feet  southward  from  this  spot,  and  which  sustained  a 
mass  of  sand,  with  rolled  pebbles  and  blocks,  some  of  them  two  or 
three  feet  in  circumference,  and  forming  a  hill  twenty  to  twenty-five 
feet  high,  containing  patches  of  loose  sand  with  fragments  of  Patella 
and  Buccinum.  It  was,  says  the  author,  easily  traced  by  several 
patches  along  the  rocks,  and  proved,  by  its  structure  and  contents, 
to  be  a  continuation  of  the  same  beach.  Dr.  Moore  likewise  briefly 
describes  another  deposit  100  yards  westward  of  the  beach,  and  at  a 
greater  elevation,  being  88  feet  above  high  water,  50  feet  in  extent, 
and  10  in  thickness,  covered  irregularly  by  soil. 

The  animal  remains  more  particularly  enumerated  by  Dr.  Moore 
consist  of  a  molar  and  part  of  the  jaw  of  a  young  elephant ;  a  femur 
of  a  rhinoceros  ;  maxillary  bones  of  a  bear,  with  the  malar  and  pala- 
tine processes,  and  two  teeth  in  each ;  an  entire  right  lower  ramus 
with  teeth  and  tusks,  the  latter  much  worn ;  four  separate  tusks ; 
several  fragments  of  long  bones ;  fragments  of  jaws  of  the  horse  con- 
taining teeth,  numerous  loose  teeth,  portions  of  long  bones,  and  two 
caudal  vertebrae  ;  likewise  portions  of  a  deer's  jaw  containing  teeth. 
The  quantity  of  the  bones  which  has  been  found  is  stated  to  be  equal 
to  several  bushels.  The  vertebrae  of  a  whale,  much  rounded,  were 
also  discovered,  with  undeterminable  portions  of  ribs.  The  animals 
to  which  the  above  remains  belonged,  are  considered  by  Dr.  Moore 
to  have  coexisted  with  those  which  inhabited  the  caves  of  Devon- 
shire. 

The  author  then  enters  upon  a  defence  of  the  opinions  contained 

*  Athenamm,  No.  721,  and  the  volume  of  Reports  of  the  British  Asso- 
ciation for  1841,  Trans,  of  the  Sections,  p.  C2  (published  1842). 

f  See  also  "  A  Succinct  Account  of  the  Lime  Rocks  of  Plymouth,"  by  the 
Rev.  R.  Hennah,  1822,  p.  58. 

X  Manual  of  Geology,  3rd  Edition,  p.  173,  1833;  also  Report  on  the 
Geology  of  Cornwall  and  Devon,  p.  423,  1839. 


544     Geological  Society :  Mr.  Colthurst  on  Contortions 

in  his  paper  read  at  Plymouth,  respecting  the  mode  of  accumulation 
of  the  bones.  He  states  that  these  osseous  remains  cannot  have 
been  derived  from  the  emptying  of  some  cave,  because  the  mass  of 
superincumbent  matter  which  has  been  removed  from  above  the 
beach  proves  that  the  bones  must  have  been  deposited  where  they 
were  found  at  a  very  ancient  period,  and  long  before  they  could  have 
been  affected  by  human  agency.  There  are  also  no  known  caves 
containing  bones  sufficiently  near.  On  the  contrary,  says  Dr. 
Moore,  if  the  sea  was  at  one  time  at  the  level  indicated  by  the  beach, 
the  Hoe  must  have  been  an  island  accessible  by  animals  at  low 
water,  and  there  appears  no  obstacle  to  the  supposition  that  the 
bears  might  have  selected  the  beach  to  devour  their  prey ;  and  the 
stranded  whale  may  have  added  to  the  banquet.  Whether  the  bones 
were  drifted  or  not,  their  occurrence  on  the  top  of  the  beach,  and 
not  in  it,  prevents,  the  author  says,  any  identity  of  time  in  their 
origin ;  but  that  the  beach  previously  existed,  and  was  of  marine 
origin,  is  proved  by  the  resemblance  of  the  deposit  to  a  modern 
beach,  and  its  containing  sea-shells  of  the  existing  period,  although 
few  in  number. 

That  the  deposit  is  not  the  result  of  glacial  action,  the  author 
observes,  is  probable  from  the  want  of  any  indication  of  such  action 
in  the  neighbouring  district ;  and  though  he  does  not  presume  to 
assert  that  this  may  not  be  a  cause  of  drift  generally,  and  even  of 
the  upper  deposit  in  the  same  locality,  yet  he  contends  that  the 
dissimilarity  in  the  composition  of  the  lower  deposit  sustains  him  in 
the  supposition  of  its  being  of  different  origin,  and  really  a  deposit 
from  the  sea.  Lastly,  Dr.  Moore,  in  reference  to  the  present  posi- 
tion of  the  beach  far  above  any  point  attained  by  the  sea  during  the 
greatest  storms,  states  that  the  deposit  must  have  been  elevated  by 
natural  causes  ;  and  that,  however  uncertain  the  exact  period  of  such 
an  event,  it  seems  to  have  occurred  at  a  time  probably  more  recent 
than  the  epoch  when  the  extinct  animals  disappeared. 

Appended  to  the  paper,  is  a  notice  of  a  specimen  of  perforated 
limestone  taken  from  the  Hoe  Lake  quarries,  eighty- five  feet  above 
the  present  level  of  high  water,  and  Dr.  Moore  maintains  his  belief 
that  the  perforations  were  formed  by  Pholades,  and  not  by  snails. 

A  paper  was  next  read,  entitled  "  An  Account  of  the  Contortions 
and  Faults  produced  in  the  Strata  underneath  and  adjacent  to  the 
great  Embankment  across  the  Valley  of  the  Brent,  on  the  Great 
Western  Railway,"  by  J.  Colthurst,  Esq. ;  communicated  by  George 
Bellas  Greenough,  Esq.,  F.G.S. 

The  author  was  induced  to  lay  this  paper  before  the  Society,  be- 
cause  he  conceives,  that,  in  the  phenomena  exhibited  by  the  sub- 
sidence in  the  Brent  embankment,  there  may  be  found  the  cause  of 
many  of  the  contortions,  faults  and  dislocations  of  strata,  especially 
among  sedimentary  rocks,  and  which  are  commonly  attributed  to 
the  agency  of  forces  acting  from  below  rather  than  to  pressure  from 
without. 

The  embankment  is  fifty-four  feet  in  height,  and  rests  on  vegetable 
soil,  beneath  which  are  four  feet  of  alluvial  clay ;  then  occurs  a  bed 


produced  in  the  strata  beneath  an  embankment.        5^5 

of  gravel  varying  from  ten  to  three  feet  in  thickness,  hut  which  thins 
out  in  some  places,  and  under  it  is  the  regular  London  clay,  traversed 
in  almost  every  direction  by  slimy  joints.  The  surface  of  the  country 
gradually  slopes  towards  the  Brent,  the  difference  of  level  between  the 
south  side  of  the  embankment  and  the  Brent  being  about  twenty  feet. 

On  the  night  of  the  21st  of  May  1837  the  embankment  began  to 
settle,  and  in  the  morning  it  was  found  that  the  foundation  had  given 
way,  and  that  on  the  south  side,  or  towards  the  Brent,  a  mass  of 
ground,  fifty  feet  long  and  fifteen  feet  wide,  had  protruded  from  under 
the  earthwork.  During  the  four  succeeding  months  this  mass  con- 
tinued to  increase  in  dimensions,  and  the  disturbance  to  extend,  so 
that  the  surface,  for  a  considerable  distance  from  the  base  of  the 
embankment,  had  assumed  an  undulated  outline,  and  the  subjacent 
beds,  where  cut  into,  exhibited  corresponding  curvatures,  overlappings 
and  cracks,  the  whole  of  which  are  described  in  the  memoir,  but  can- 
not be  rendered  intelligible  without  diagrams.  In  the  embankment 
itself  the  symptoms  of  failure  were  confined  to  a  settlement  of  about 
fifteen  feet,  and  a  large  fissure  near  the  top,  on  the  side  opposite  to 
that  where  the  foundation  had  yielded,  and  which  extended  the  whole 
length  of  the  slip.  To  this  fissure,  and  its  dip  towards  the  disturb- 
ance at  the  base  of  the  embankment,  the  author  particularly  directs 
attention,  as  he  infers  from  it  the  nature  and  inclination  of  a  fault 
exhibited  in  the  diagrams  which  illustrate  the  memoir. 

At  the  end  of  twelve  additional  months,  during  which  the  embank- 
ment continued  to  slip,  and  the  disturbance  at  the  base  to  increase, 
Mr.  Brunei  directed  a  supplementary  earthwork  or  terrace  to  be 
thrown  down  upon  the  swollen  surface,  and  it  was  an  effectual  re- 
medy. Up  to  this  time  the  total  subsidence  had  exceeded  thirty 
feet ;  and  the  swollen  ground,  which  extended  nearly  400  feet  in 
length,  and  from  seventy  to  eighty  feet  in  width,  had  attained  an 
average  height  of  ten  feet,  with  a  horizontal  motion  of  fifteen  feet ; 
but  the  general  disturbance  ranged  to  a  distance  of  220  feet  from 
the  foot  of  the  slope,  or  to  the  Brent,  the  bank  of  which  was  forced 
five  feet  forwards  :  the  faults  varied  from  thirty  feet  to  two  feet,  and 
the  contortions  had  attained  a  curvature,  the  semi- axis  of  which  was 
in  many  places  eight  feet. 

The  author  then  dwells  on  the  magnitude  of  the  disturbance,  and 
on  the  effects  which  may  have  been  produced  in  the  strata  com- 
posing the  earth's  surface,  by  pressure  from  above.  He  says,  that  in 
consequence  of  the  great  inequality  in  the  thickness  of  the  sedimen- 
tary rocks,  due  to  the  conditions  under  which  they  were  deposited, 
great  inequality  of  pressure  must  have  arisen,  and  consequently  con- 
tortions and  faults  have  been  produced,  varying  in  amount  according 
to  the  thickness  and  the  degree  of  consolidation  in  the  strata  them- 
selves. In  support  of  his  argument,  the  author  quotes  a  passage 
contained  in  Mr.  Greenough's  'Critical  Examination  of  the  Principles 
of  Geology,'  and  which  asks  the  question  whether  contortions  may 
not  have  taken  place  where  clay  alternates  with  limestone  or  silex, 
in  consequence  of  an  unequal  rate  of  consolidation  (p.  77).  The 
author  also  alludes  to  the  theory  of  Sir  James  Hall,  but  chiefly  to 

Phil,  Mag.  S.  3.  No.  U 1 ,  SuppU  Vol.  2 1 .  2  O 


54:6       Geological  Society :  Mr.  Pearce  on  Ammonites^ 

prevent  its  being  "  mixed  up  in  any  way  with  the  subject  of  this  paper, 
or  the  inferences  it  contains ; "  and  lastly,  he  wishes  it  may  be  clearly 
understood,  that  while  he  advocates  the  explanation  of  many  geolo- 
gical phenomena  by  means  of  pressure  from  without,  he  does  not 
propose  that  all  geological  disturbance  should  be  attributed  to  it ; 
nor  does  he  deny  that  many,  and  more  especially  the  most  consider- 
able, irregularities  in  the  structure  of  the  earth  may  and  must  be 
assigned  to  other  causes. 

"  Notice  on  the  occurrence  of  Plants  in  the  Plastic  Clay  of  the 
Hampshire  Coast,"  by  the  Rev.  P.  B.  Brodie,  F.G.S.,  was  then  read. 

The  cliffs  to  the  east  and  west  of  Bournemouth  are  composed  of 
horizontal  strata  belonging  to  the  plastic  clay  formation.  East  of 
the  town  they  consist  of  white  and  yellow  sands,  the  former  con- 
taining fragments  of  wood.  Further  along  the  shore  the  cliffs  arc 
higher,  and  beds  of  clay  full  of  vegetable  remains  appear  under 
the  sands.  About  half  a  mile  beyond,  a  stratum  of  fine  white  sand, 
three  or  four  feet  thick,  situated  near  the  middle  of  the  cliffs,  con- 
tains impressions  of  ferns  ;  and  a  layer  of  sand  and  clay  is  full  of 
small  leaves.  The  subjacent  strata  of  clay  are  separated  by  thin 
layers  of  vegetable  matter.  Somewhat  further,  beds  of  white  and 
yellow  sand  and  sandy  clay  abound  with  beautiful  leaves,  and  the 
surface  of  the  strata  is  in  some  places  covered  with  a  thin  layer  of 
iron-sand  containing  impressions  of  ferns.  In  most  cases,  the  vari- 
ous-coloured  sands  are  divided  by  beds  of  clay,  and  their  fossil  con- 
tents are  distributed  in  layers  at  rather  distant  intervals.  Mr.  Brodie 
did  not  discover  any  shells.  Several  of  the  fossil  plants  are  stated 
by  the  author  to  belong  to  the  Lauracea  and  Amentacea;  but  he 
says  that  these,  as  well  as  others  which  he  arranges  among  the 
Characea  and  Cryptogami,  and  some  of  which  he  has  not  determined 
the  characters,  are  all  geaerically  distinct  from  any  British  plant,  and 
belong  to  those  of  a  warmer  climate.  When  the  sandstone  is  freshly 
broken  the  epidermis  of  the  fossil  frequently  peels  off,  leaving  the 
impression  of  only  the  fibres.  These  remains  often  form  masses  of 
some  thickness ;  and,  from  their  state  of  preservation,  must,  the 
author  states,  have  been  deposited  tranquilly  beneath  the  waters. 

A.paper  "  On  the  Mouths  of  Ammonites,  and  on  Fossils  contained 
in  laminated  beds  of  the  Oxford  Clay,  discovered  in  cutting  the  Great 
"Western  Railway,  near  Christian  Malford  in  Wiltshire."  By  J. 
Chaning  Pearce,  Esq.,  F.G.S.,  was  lastly  read. 

Mr.  Pearce  commences  by  stating,  that  his  attention  was  first  di- 
rected to  this  part  of  the  railway  by  the  impression  of  a  crushed 
Ammonite  procured  at  Cheltenham  in  April  1841,  but  that  he  was 
prevented  from  examining  the  locality  for  three  or  four  months. 

The  following  section  of  the  beds  is  given  by  Mr.  Pearce  : — 

1 .  Alluvial  soil 2  feet. 

2.  Gravel 8  ... 

3.  Four  or  five  bands  of  laminated  clay,  al- 

ternating with  sandy  clay,  almost  en- 
tirely composed  of  broken  shells. ...      6  ... 

4.  Clay,  containing  Gryphaa  bilobata. 


and  on  Fossils  in  the  Oxford  Clay.  54-7 

The  objects  of  the  author  are,  first,  to  draw  attention  to  the  organic 
bodies  discovered  in  the  laminated  clay ;  and  secondly,  to  describe 
the  various  forms  which  the  mouth  of  the  Ammonite  assumes  in 
different  species  and  in  different  stages  of  growth  in  the  same 
species. 

The  fossils  obtained  from  the  laminated  clay  are  stated  to  be  as 
follows  : — 1.  A  succulent  plant.  2.  Lignite,  with  oysters  sometimes 
affixed  to  it.  3.  Crustaceans,  supposed  to  have  inhabited  the  dead 
shell  of  the  Ammonite*.  The  specimen  described  is  stated  to  have  a 
finely  tuberculated  and  delicately  thin  covering  ;  the  tail  to  have 
the  appearance  of  being  divided  into  three  portions,  finely  corrugated 
towards  their  edges ;  the  body  to  have  on  each  side  internally  five 
or  more  processes ;  and  the  head  to  be  furnished  with  several  short 
arms  and  two  long  ones  jointed  a  little  above  the  head  and  ter- 
minated in  two  claws,  the  longer  being  serrated  on  its  inner  edge. 
4.  Another  allied  crustacean  is  stated  to  have  also  an  extremely  thin 
and  finely  tuberculated  covering ;  to  be  furnished  with  two  long  arms 
of  similar  shape,  each  terminated  at  its  extremity  by  one  claw,  and 
two  others  projecting  from  about  the  centre  ;  and  passing  off  poste- 
riorly are  two  fan-like  processes  of  similar  shape.  5.  Trigonellites, 
two  species.  6.  One  valve  of  a  Pollicipes.  7.  The  remains  of  an 
animal  considered  to  have  been  probably  allied  to  a  Sepia.  8.  Shells 
of  the  genera  Unio,  Cyclas,  Astarte,  Avicula,  Gervilla,  Pinna,  Nu- 
cula,  Rostellaria,  Turritella,  Ammonites  f,  Belemnites,  and  an  animal 
to  which  he  has  applied  (since  the  paper  was  read)  the  name  of  Be- 
lemnotheutis.  In  describing  the  last  fossil,  he  states  that  the  lower 
part  is  conical,  blunt  at  the  apex,  and  chambered  internally  like  the 
alveolus  of  a  Belemnite,  with  an  oval  siphunculus  near  the  edge  of 
the  chambers  ;  that  it  has  a  brown  thick  shelly  covering  which  gra- 
dually becomes  thinner  towards  the  superior  part ;  that  immediately 
above  the  chambers  is  an  ink-bag  resting  on  what  resembles  the 
upper  part  of  a  sepiostaire,  and  composed  of  a  yellow  substance 
finely  striated  transversely,  being  formed  of  laminae  of  unequal  den- 
sity ;  that  in  some  specimens,  broken  longitudinally  through  the 
middle,  are  exposed  long,  flat,  narrow  processes  of  a  different  struc- 
ture ;  that  immediately  beneath  the  superior  contraction  are  two 
long  feather-like  processes,  and  one  or  more  which  are  short,  indica- 
ting, the  author  thinks,  probably  the  situation  of  the  mouth.  With 
reference  to  the  first  part  of  the  paper,  Mr.  Pearce  also  notices  an 
animal  allied  to  Sepia  or  Loligo,  one  side  being  covered  by  a  pen 
resembling  that  of  the  Loligo,  and  having  immediately  underneath 
it,  at  the  junction  of  the  middle  with  the  lower  third,  an  ink-bag 

*  To  this  organic  body  Mr.  Pearce  has  given  since  the  paper  was  read 
the  name  of  Ammonicolax. 

\  Since  the  paper  was  written  Mr.  Pearce  has  consulted  Mr.  Pratt's  ac- 
count in  the  Annals  of  Natural  History  for  November  1841,  of  Oxford 
clay  Ammonites,  and  ascertained  that  he  possesses  [A.  Lonsdalii,  A.  Brightii], 
\_A.  Gutielmi,  A.  ElizabethecB],  A.  Comptoni,  and  A.  Konigii.  The  fossils 
included  between  brackets  the  author  considers  to  belong  to  one  species. 

2  02 


54-8       Geological  Society :  Mr.  Lyell  on  the  Recession 

resting  on  what  resembles  a  sepiostaire.  He  mentions  likewise  ten  or 
twelve  species  of  fishes,  but  without  giving  names  ;  also  coprolites. 

2.  Respecting  the  form  of  the  mouth  of  the  Ammonites  and  the 
changes  at  different  periods  of  growth,  Mr.  Pearce  states  his  belief, 
that  the  terminal  lip  or  mouth  has  a  different  shape  in  the  young 
shell  of  almost  every  species,  but  assumes  in  the  old  a  straight  out- 
line, and  that  he  has  been  aware  of  this  circumstance  several  years. 
Of  cases  of  young  shells  with  differently  shaped  lips,  he  mentions 
Ammonites  Brongniarti  (Inf.  oolite),  A.  sublcevis  (Oxf.  clay),  A.  ob- 
tusus  (Lias),  A.  Kamigii  (Kelloway  Rock,  the  mature  shell  is  stated 
to  have  a  straight  mouth),  A.  Calloviensis  (Kelloway  Rock,  the  lip  of 
the  old  shell  is  stated  to  be  slightly  contracted  and  to  terminate  with 
gently  undulating  sides),  A.  Walcottii  (Lias),  and  A.  Goodhalli,  fur- 
nished in  the  mature  state  with  a  single  horn-like  projection  at  the 
front  of  the  mouth.  In  addition  to  these  species  he  enumerates  those 
noticed  in  the  preceding  part  of  the  paper.  Mr.  Pearce  is  further  of 
opinion  that  at  different  periods  of  the  formation  of  the  shell  the  la- 
teral processes  were  absorbed  and  reproduced,  and  that  therefore 
they  are  found  in  various  stages  of  growth,  but  are  invariably  want- 
ing in  the  mature  shell.  In  some  species  in  which  the  successive 
mouths  were  much  contracted  or  expanded,  the  new  shell  the  author 
says  was  continued  without  the  absorption  of  the  lip,  leaving  a  highly 
projecting  rib  or  a  deep  furrow*. 

After  a  careful  examination  of  upwards  of  twenty  species  in  his 
collection,  with  perfect  mouths  of  all  ages  and  from  different  strata, 
not  including  the  Oxford  clay,  Mr.  Pearce  has  found  the  external 
chamber  to  vary  considerably  in  extent,  occupying  in  some  speci- 
mens the  whole  of  the  last  whorl,  but  in  others  less  than  one-third, 
and  without  reference  to  age  or  species ;  and  he  therefore  suggests 
that  the  young  animal  of  the  Ammonite  filled  the  whole  of  the  outer 
chamber,  extending  also  to  the  extreme  points  of  the  lateral  pro- 
cesses in  those  species  which  were  provided  with  them  ;  and  thereby 
not  only  received  support  but  afforded  protection  to  a  portion  of  the 
shell  extremely  liable  to  injury.  In  old  individuals  he  is  of  opinion 
that  the  animal  when  quiescent  was  entirely  contained  within  the 
last  chamber. 

Jan.  19th. — "A  Memoir  on  the  Recession  of  the  Falls  of  Niagara," 
by  Charles  Lyell,  Esq.,  V.P.G.S.,  was  read. 

The  general  features  of  the  physical  geography  of  the  district  tra- 
versed by  the  Niagara  between  Lakes  Erie  and  Ontario,  Mr.  Lyell 
says,  have  been  described  with  a  considerable  approach  to  accuracy 
by  several  writers.  Prof.  Eaton,  in  a  small  work  published  in  1 824  f, 
gives  a  correct  section  of  the  formations  between  Lewistown  and 
the  Falls  of  Niagara,  and  also  refutes  the  hypothesis  of  the  Lewis- 
town  escarpment  being  due  to  a  fault  by  an  exposition  of  the  true 

*  The  author  was  not  acquainted  with  M.  Al.  d'Orbigny's  work,  Pal. 
Francalse,  when  he  wrote  the  paper,  and  was  not  aware  of  the  views  given 
in  it  respecting  the  mouth  of  the  Ammonite. 

f  Mr.  Lyell's  attention  was  called  to  this  work  by  Mr.  Conrad. 


of  the  Falls  of  Niagara.  549 

structure  of  the  country.  Mr.  R.  Bakewell  in  1830*,  published  an 
account  of  the  country  adjacent  to  the  Falls,  and  Mr.  De  la  Beche 
in  1831  f»  endeavoured  to  point  out  the  gradual  manner  in  which 
the  receding  Falls,  if  they  should  ever  reach  Lake  Erie,  would  dis- 
charge the  waters  of  the  lake;  Prof.  D.  Rogers  also  in  1835  J 
showed  distinctly,  that,  as  the  Falls  retrograde,  they  would  cut 
through  rocks  entirely  distinct  from  those  over  which  the  waters  are 
now  precipitated,  and  correctly  represents  the  superior  limestone  at 
Buffalo  as  newer  than  the  limestone  of  the  Falls,  though  he  omits 
the  intervening  saliferous  formation.  Mr.  Conrad  likewise,  in  his 
Report  for  1837  §,  first  assigned  all  the  formations  of  the  country  to 
the  Silurian  system  ;  but  to  Mr.  James  Hall  (1838)  ||  is  due  the  merit 
of  having  shown  the  true  geological  succession  of  rocks  of  the  di- 
strict. 

The  contents  of  the  memoir  may  be  divided  into  two  parts  :  I.  an 
account  of  the  successive  strata  of  the  Niagara  district ;  and  II.  a 
description  of  the  phenomena  exhibited  by  the  Falls. 

I.  His  sketch  of  the  geology  of  the  district,  the  author  states,  is 
derived  either  from  the  published  surveys  of  Mr.  Hall,  or  from  the 
information  he  obtained  while  travelling  with  that  gentleman  in  the 
State  of  New  York  during  the  autumn  of  1841 ;  and  he  acknow- 
ledges the  great  advantage  he  derived  from  the  facilities  thus  afforded 
him.  The  strata  between  Lakes  Erie  and  Ontario  appear  to  belong 
to  the  middle  and  lower  portions  of  the  English  Silurian  system,  and 
they  are  divisible  into  the  following  five  principal  formations:  1st. 
the  Helderberg  limestone  ;  2nd,  the  Onondago  salt  group ;  3rd,  the 
Niagara  group ;  4th,  the  Protean  group  ;  and  5th,  the  Ontario  group, 

1.  The  Helderberg  limestone,  which  has  derived  its  designation 
from  the  range  of  mountains  of  the  same  name,  and  is  the  newest 
formation  of  the  country,  is  exposed  where  the  Niagara  flows  out  of 
Lake  Erie,  and  on  account  of  the  organic  remains  with  which  it 
abounds,  it  is  considered  to  be  the  equivalent  of  the  Wenlock  rocks 
of  Mr.  Murchison's  Silunan  system.  The  correctness  of  this  stra- 
tigraphical  position  Mr.  Lyell  has  verified  by  an  examination  of  the 
succession  of  formations  from  the  coal-field  on  the  borders  of  Penn- 
sylvania to  the  group  in  question,  the  intervening  deposits  consist- 
ing, first,  of  old  red  sandstone,  having  at  its  bottom  a  large  develop- 
ment of  shales  and  sandstones  called  the  Chemung  and  Ithaca  for- 
mations, but  containing  organic  remains  which  resemble  those  of  the 
Devonian  system;  and  then  1000  feet  of  Ludlowville  shales  with 
fossils  analogous  to  those  of  the  Ludlow  rocks  of  Mr.  Murchison. 
The  superposition  of  this  vast  horizontal  series  is  beautifully  ex- 
posed in  the  banks  of  the  Genessee  and  other  rivers ;  and  near  Le  Roy 
as  well  as  elsewhere,  the  Helderberg  limestones  crop  out  from  be- 
neath them.     On  account  of  the  middle  portion  containing  nodules 

*  Loudon's  Magazine  of  Natural  History,  1830. 

f  Manual  ofGeology,  three  editions,  1831, p.  55;  1832,  p.  55;  1833,  p.  60. 

X  Silliman's  Journal,  vol.  xxvii.  p.  326. 

§  States'  Report  of  the  Geology  of  NewYork. 

||  Geological  Report  of  the  State  of  New  York  for  1838. 


550      Geological  Society :  Mr.  Lyell  on  the  Recession 

and  layers  of  chert,  the  whole  deposit  was  first  called  the  corni- 
tiferous  formation  by  Prof.  Eaton.  In  this  part  of  the  State  of  New 
York,  and  still  further  to  the  west,  in  Upper  Canada,  the  limestone 
is  only  50  feet  thick,  whereas  at  Schoharie  in  the  Helderberg  moun- 
tains, 300  miles  to  the  eastward,  its  thickness  is  300  feet. 

2.  The  Onondago  salt  group. — This  series  of  beds,  Mr.  Lyell  says, 
is  extremely  unlike  any  described  member  of  the  European  Silurian 
group.  With  the  exception  of  a  stratum  of  limestone  at  the  top 
containing  Cytherina,  it  consists  of  red  and  green  marls  with  beds  of 
gypsum,  the  former  being  undistinguishable  from  the  marls  of  the  new 
red  system  of  England ;  and  they  are  also  destitute  of  fossils.  Salt 
springs  are  of  frequent  occurrence,  but  no  rock  salt  has  been  disco- 
vered in  the  group.  The  breadth  of  the  zone  of  country  occupied  by 
the  deposit  is  not  less  than  16  miles,  and  Mr.  Hall  infers  from  it  and 
the  slight  southerly  dip  of  the  strata,  that  the  entire  thickness  in  the 
neighbourhood  of  the  Niagara  is  at  least  800  feet,  an  estimate  con- 
firmed by  the  nearest  sections  eastward  of  the  river.  In  some  parts 
of  the  State  of  New  York  the  thickness  is  not  less  than  1000  feet. 
Along  the  Niagara  the  formation  has  been  greatly  denuded,  and  is 
covered  by  superficial  drift,  except  at  a  few  places. 

3.  The  Niagara  group. — This  series  of  beds  commences  near  the 
rapids,  above  the  great  cataract.  It  comprises,  1st,  the  Niagara,  or 
Lockport  limestone,  and  2ndly,  the  Niagara,  or  Rochester  shale ; 
and  it  contains  in  both  divisions  fossils  identical  with  those  of  the 
Wenlock  limestone  of  England,  with  others  peculiar  to  North  Ame- 
rica. The  limestone  at  the  rapids  and  the  Falls  is  120  feet  thick ;  the 
upper  40  feet,  being  thin-bedded,  have  given  way  to  the  frost  and  the 
action  of  the  stream ;  but  the  lower  80  feet,  being  massive,  forms  at 
the  cataract  a  precipice,  beneath  which  occurs  the  shale,  also  80  feet 
thick. 

4.  The  Protean  group. — Under  the  water  at  the  base  of  the  Falls 
crop  out  the  higher  beds  of  this  formation,  the  name  of  which  has 
been  derived  from  the  variable  nature  of  its  component  strata.  In 
the  district  more  particularly  described  in  this  paper  the  group  is 
only  30  feet  thick,  but  farther  to  the  eastward  it  attains  thrice  those 
dimensions.  On  the  Niagara  it  consists  of  25  feet  of  hard  limestone, 
resting  on  4  feet  of  shale ;  while  at  Rochester,  eighty  miles  to  the 
eastward,  it  comprises,  among  other  beds,  a  dark  shale  with  grapto- 
lites,  or  fossiliferous  iron  ore,  and  beneath  them  a  limestone  full  of 
Pentamerus  oblongus  and  P.  Icevis,  considered  by  Mr.  Conrad  to  be 
one  species.  On  account  of  the  occurrence  of  this  shell,  the  whole 
of  these  strata  have  been  separated  from  the  Niagara  series. 

5.  Ontario  group.— About  half  a  mile  below  the  Falls  the  upper- 
most beds  of  the  Ontario  group  crop  out.  At  the  whirlpool  they 
have  a  thickness  of  70  feet,  and  at  Queenstown  of  200,  but  to  the 
latter  dimension  must  be  added  150  feet  of  inferior  beds,  exposed 
between  Queenstown  and  Lake  Ontario.  The  entire  group  con- 
sists of 

1 .  Red  marl  with  beds  of  hard  sandstone  in  its  "|    „„  ,    , 


upper  division 


*} 


of  the  Falls  of  Niagara.  551 

2.  White  quartzose  strata,  so  hard  as  to  form~| 

at  Queenstown  a  ledge  projecting  beyond  >  25  feet 
the  face  of  the  escarpment J 

3.  Red  marl  and  sandstone 250   ... 

Other  divisions  of  the  group,  concealed  beneath  the  waters  of  the 
lake,  may  be  studied  in  the  cliffs  of  its  eastern  and  north-eastern 
shores. 

Mr.  Lyell  next  proceeds  to  give  a  brief  account  of  the  geographical 
distribution  of  the  formations  or  groups.  The  strike  of  the  beds  be- 
ing east  and  west,  and  the  dip  very  slight  towards  the  south,  the 
sections  exposed  along  the  Niagara  afford  a  key  to  the  structure  of 
a  large  portion  of  the  State  of  New  York,  the  same  deposits  having 
been  traced  eastward  through  a  region  40  miles  in  breadth  by  150 
in  length,  and  westward  to  a  much  greater  distance.  The  Helder- 
berg  and  the  Niagara  limestones  constitute  platforms  which  ter- 
minate in  parallel  escarpments,  from  twenty  to  twenty-five  miles 
apart,  about  sixteen  miles  of  the  intervening  space  being  occupied 
by  the  saliferous  group.  The  Helderberg  escarpment,  to  the  east 
of  Buffalo,  is  50  feet  high ;  but  in  the  neighbourhood  of  the  Nia- 
gara it  has  been  denuded  and  is  half  buried  beneath  drift ;  it  is  how- 
ever resumed  in  Upper  Canada,  and  eastward  it  may  be  followed  to 
the  river  Hudson.  The  Niagara  limestone  escarpment  presents  at 
Lewistown  and  Queenstown  a  cliff  300  feet  high,  which  may  be 
traced  eastward  nearly  100  miles  and  westward  for  a  much  greater 
distance.  The  limestone  series,  however,  constitutes  only  the  up- 
permost third  of  the  escarpment,  the  remainder  being  composed  of 
the  Protean  and  the  Ontario  groups ;  the  whole  section  being  as  fol- 
lows : — 

1 .  Niagara  limestone,  lower  beds 30  feet. 

2.  Niagara,  or  Rochester  shale 80  ... 

3.  Protean  beds 30   ... 

4.  Ontario  group  :  red  marl,  with  hard  beds  in!     7ft 

the  upper  part J 

5. :    quartzose  grey  sandstone,!     9_ 

with  Lingular,  &c J 

6 :  red  marl 100   ... 

335  feet. 
Though  only  the  lower  beds  of  the  Niagara  limestone  occur  in  the 
escarpment  at  Lewistown,  yet,  in  consequence  of  the  gentle  rise  of 
the  strata  to  the  north,  the  summit  of  these  lower  beds  is  at  a  higher 
level  than  that  of  Lake  Erie.  The  whole  of  the  Niagara  platform  is 
covered  irregularly  with  hillocks  of  drift,  beneath  which  the  lime- 
stone is  polished  and  furrowed. 

From  the  foot  of  the  Queenstown  escarpment  to  Lake  Ontario,  a 
distance  of  six  or  seven  miles,  is  a  low  tract,  consisting  of  sandstones 
belonging  to  the  Ontario  group,  and  dipping  like  the  preceding  beds 
slightly  to  the  south. 

A  section  which  accompanied  the  memoir  to  illustrate  the  pre- 
ceding details  corresponds,  the  author  says,  in  all  essential  particu- 


552       Geological  Society :  Mr  Lyell  on  the  Recession 

lars  with  one  previously  published  by  Mr.  Hall ;  but  the  whole  suc- 
cession of  beds  has  been  verified  by  Mr.  Lyell  in  more  than  one 
line  of  section,  from  north  to  south.  He  is  induced  to  believe,  from 
a  comparison  of  English  Caradoc  and  Llandeilo  fossils  with  suites  of 
organic  remains  examined  in  America,  that  a  series  of  beds  which 
underlie  the  Ontario  group,  and  termed  by  American  geologists  the 
Mohawk  group,  may  be  older  than  the  lower  Silurian  rocks,  and 
wanting  in  England. 

II.  On  the  Recession  of  the  Falls. — The  following  measurements, 
Mr.  Lyell  says,  are  of  great  importance  in  speculating  on  the  past  or 
future  recession  of  the  Falls.  The  distance  from  the  point  where  the 
Niagara  flows  out  of  Lake  Erie  to  the  Falls  is  sixteen  miles,  thence 
to  the  limestone  escarpment  seven  miles,  and  from  this  point  to  Lake 
Ontario  about  seven  more.  From  Lake  Erie  to  the  commencement 
of  the  rapids,  fifteen  miles  and  a  half,  the  river  falls  only  15  feet ; 
but  from  the  top  of  the  rapids  to  the  great  cataract  the  descent  is 
45  feet ;  and  the  height  of  the  Falls  is  164  feet,  perpendicular.  From 
the  base  of  the  Falls  to  Queenstown,  seven  miles,  the  difference  of 
level  in  the  river  is  about  100  feet ;  but  from  that  place  to  Lake  On- 
tario, seven  miles  further,  it  is  only  3  or  4  feet.  If  the  Falls  were 
ever  at  Queenstown,  they  must,  the  author  observes,  have  been  about 
twice  their  present  height,  having  lost  a  small  portion  of  the  dif- 
ference by  the  southern  inclination  of  the  strata,  and  rather  more 
than  100  feet  by  the  rise  of  the  bed  of  the  river. 

With  respect  to  the  opinion  of  the  Queenstown  escarpment  being 
due  to  a  fault,  Mr.  Lyell  states,  that  the  strata  on  the  banks  of  the 
Niagara,  both  above  and  below  Queenstown,  presenting  the  same 
relative  position  as  at  Lockport  or  Rochester,  the  escarpment  must 
be  entirely  due  to  denudation ;  and  he  has  no  hesitation  in  attribu- 
ting this  escarpment,  as  well  as  the  Helderberg,  to  the  action  of  the 
sea ;  these  great  inland  cliffs  having  far  too  great  a  range  to  have  re- 
sulted from  a  former  extension  and  higher  altitude  of  Lake  Ontario. 

The  next  question,  whether  the  ravine  through  which  the  Niagara 
flows  is  to  be  regarded  as  a  prolongation  of  the  Queenstown  escarp- 
ment and  referable  to  the  same  period,  or  has  been  cut  through  by 
the  river,  is,  the  author  states,  of  greater  difficulty.  From  his  own 
observations,  he  concludes  that  the  ravine  has  been  formed  by  the 
river ;  but  he  assumes,  that  a  shallow  valley  pre-existed  along  the 
line  of  the  present  defile,  resembling  the  present  one  between  Lake 
Erie  and  the  Falls.  His  reasons  for  conceiving  that  the  river  has 
been  the  excavating  agent,  are,  1st,  the  ravine  being  only  from  400 
to  600  yards  wide  at  the  top,  and  from  200  to  400  at  the  bottom, 
between  Queenstown  and  the  Whirlpool ;  2ndly,  the  inclination  of 
the  bed  of  the  river,  14^  feet  per  mile,  being  everywhere  cut  down  to 
the  regular  strata ;  3rdly,  the  fact  that  the  Falls  are  now  slowly  re- 
ceding ;  4thly,  that  a  freshwater  formation,  which  the  author  ascribes 
to  the  body  of  water  which  flowed  along  the  original  shallow  valley, 
exists  on  Goat  Island  and  half  a  mile  lower  down  the  river,  and 
could  not  have  been  deposited  after  the  Falls  had  receded  farther 
back  than  the  Whirlpool.    Mr.  Lyell  considers  that  the  indentation 


of  the  Falls  of  Niagara,  553 

of  about  two  acres  on  the  American  side  of  the  Niagara,  and  not  re- 
ferable to  the  action  of  that  river,  is  no  objection  to  the  theory  of  the 
recession  of  the  Falls,  because  he  conceives  that  the  stream  flowing 
down  it  could  have  effected  the  denudation,  aided  by  atmospheric 
agents  ;  and  because  a  similar  objection  might  be  founded  on  a  ra- 
vine on  the  Canada  side  opposite  the  Whirlpool,  where  several  par- 
allel gullies  have  been  deeply  eaten  into  by  streams.  The  charac- 
ters of  this  ravine  were  carefully  examined  by  Mr.  Lyell  and  Mr. 
Hall,  and  appear  to  have  escaped  previous  observers.  What  was 
anciently  a  ravine  joins  the  defile  of  the  Niagara  at  this  point,  but 
it  is  entirely  filled  with  horizontal  beds  of  drifted  pebbles,  sand  and 
loam  ;  the  first,  near  the  bottom  of  the  deposit,  having  been  cemented 
into  a  conglomerate  by  carbonate  of  lime.  This  is  the  only  interrup- 
tion of  the  regular  strata  along  the  course  of  the  Niagara ;  and  Mr. 
Lyell  observes,  it  is  desirable  to  ascertain  if  it  be  a  prolongation  of 
the  ravine  which  intersects  the  great  escarpment  at  St.  David's,  west 
of  Lewistown. 

The  author  states,  that  he  is  by  no  means  desirous  of  attaching 
importance  to  the  precise  numerical  "calculations  which  have  been 
made  respecting  the  number  of  yards  that  the  Falls  have  receded 
during  the  last  half  century,  as  there  are  no  data  on  which  accurate 
measurements  could  be  made  ;  and  because  fifty  years  ago  the  district 
was  a  wilderness.  Mr.  Ingrahaw  of  Boston  has,  however,  called  his 
attention  to  a  work  published  by  the  French  Missionary,  Father  Hen- 
nipen,  in  which  a  view  is  given  of  the  Falls  as  they  appeared  in  1678. 
Goat  Island  is  represented  dividing  the  waters  as  at  present ;  but 
besides  the  two  existing  cascades,  a  third  is  depicted  on  the  Canada 
side,  crossing  the  Horse- shoe  Fall  at  right  angles,  and  appears  to 
have  been  produced  by  a  projection  of  the  Table  Rock.  In  the  de- 
scription Father  Hennipen  states,  that  this  smaller  cascade  fell  from 
west  to  east,  and  not  like  the  other  two,  from  south  to  north. 

Seventy- three  years  afterwards,  in  1751,  a  letter  on  the  Falls,  by 
Kalm,  the  Swedish  botanist,  was  published  in  the  *  Gentleman's  Ma- 
gazine.' It  is  illustrated  by  a  plate,  in  which  the  third  Fall  is  omit* 
ted ;  but  the  writer  states  in  a  note,  that  at  that  point  the  water 
was  formerly  forced  out  of  its  direct  course  by  a  projecting  rock,  and 
turned  obliquely  across  the  other  Fall  *. 

Mr.  Lyell  then  proceeds  to  show  what  are  the  geological  evidences 
of  the  former  prolongation  of  the  river's  bed,  on  a  level  with  the  top 
of  the  ravine  through  which  the  Niagara  now  flows.  The  existence 
on  Goat  Island  of  strata  of  marl,  gravel  and  sand,  containing  fossil 
freshwater  shells,  was  known  before  Mr.  Bakewell's  paper  on  the 
Falls  was  published,  and  they  have  been  more  recently  described  by 
Mr.  Hall  f  ;  and  Mr.  Lyell  states,  that  he  was  very  desirous  of 
ascertaining  how  far  they  extend  on  the  banks  of  the   river,  or 

*  The  author  has  observed  distinct  signs  of  recession  in  strata  of  the 
Silurian  and  Devonian  epochs  at  the  Falls  of  the  Genessee  in  Rochester 
and  at  Portage,  at  the  Fall  of  Allen's  Creek  below  Le  Roy,  near  the  town 
of  Batavia,  and  at  the  Falls  of  Jacock's  river,  three  miles  north  of  Genessee, 

t  Report  for  1838. 


554<  Geological  Society :  Mr.  D.  Sharpe  on  the 

whether  they  could  be  detected  below  the  present  Falls.  On  the 
south-west  side,  in  a  cliff  12  feet  in  perpendicular  height,  a  bed  of 
gravel,  7  feet  from  the  surface,  contains  eight  species  of  fluviatile 
and  one  of  terrestrial  shells,  determined  for  the  author  by  Dr. 
Gould  of  Boston,  the  whole  of  the  former  now  living  in  the  wa- 
ters of  the  Niagara,  and  some  of  them  even  in  the  rapids.  At  the 
south-west  extremity  of  Goat  Island  this  deposit  must  be  24  feet 
thick,  and  it  rests  on  the  Niagara  limestone.  On  the  right  bank 
of  the  river,  opposite  the  island,  are  two  river-terraces,  one  12  feet 
above  the  stream,  and  the  other  12  feet  higher;  and  both  have 
been  cut  out  of  this  freshwater  formation.  In  making  a  mill-dam 
some  years  ago,  the  same  species  of  shells  as  those  on  Goat  Island 
were  thrown  out,  and  Mr.  Lyell  had  still  an  opportunity  of  col- 
lecting them.  He  was  also  shown  a  tooth  of  the  "Mastodon  Ameri- 
canus,"  which,  with  another  tooth  and  a  bone  of  the  same  animal, 
were  discovered  in  the  deposit  13  feet  from  the  surface.  From  in- 
formation given  to  the  author  by  Mr.  Hooker,  the  guide,  the  forma- 
tion was  found  half  a  mile  farther  down  the  river,  at  the  summit  of 
the  lofty  precipice,  6  feet  deep  and  composed  chiefly  of  gravel.  It 
contained  in  abundance  Cyclas  rhomboidea,  Valvata  tricarinata  and 
Planorbis  parvus.  This  patch  of  gravel  demonstrates,  therefore,  the 
former  position  of  the  river  at  a  level  corresponding  to  that  of  the 
present  summit  of  the  cataract,  and  half  a  mile  below  the  existing 
Falls.  It  proves  however,  Mr.  Lyell  says,  much  more  ;  for  in  order 
that  such  a  fluviatile  deposit  should  have  been  accumulated  in  water 
tranquil  enough  to  allow  those  shells  to  exist,  there  must  have  been 
a  barrier  farther  down ;  and  he  is  of  opinion  it  may  be  safely  placed 
as  low  as  the  Whirlpool,  or  three  miles  from  the  present  Falls.  If 
this  be  admitted,  then,  the  author  says,  "  we  may  be  prepared  to 
concede  that  the  still  narrower  ravine  beyond  the  Whirlpool  was 
excavated  by  the  river  cutting  back  its  course." 

A  similar  terrace,  consisting  of  the  Goat  Island  deposit,  is  di- 
stinctly seen  also  on  the  Canada  side,  and  at  about  the  same  level 
between  the  Falls  and  the  Whirlpool ;  but  its  extent,  height  and 
fossil  contents  have  not  been  investigated. 

If,  Mr.  Lyell  observes,  the  river  continue  to  intersect  its  way 
back,  the  sediment  now  depositing  in  its  bed,  above  the  Falls,  will 
be  laid  dry  in  places,  and  cut  into  in  the  same  manner  as  the  Goat 
Island  deposit. 

Assuming  that  the  cataract  was  once  at  the  Queenstown  escarp- 
ment, allowance  must  be  made,  in  speculating  on  the  probable 
time  which  has  elapsed  in  cutting  the  ravine,  for  a  very  different 
rate  of  retrocession  at  different  periods,  dependent  on  the  changes 
in  the  formation  intersected,  especially  of  those  which  successively 
constituted  the  base  of  the  precipice.  At  Queenstown  and  Lewis- 
town  the  fundamental  rock,  at  the  period  when  the  Falls  were  there, 
was  a  soft  red  marl,  and  the  river  acted  upon  the  same  deposit  for 
about  three  miles,  where  the  rise  in  the  channel,  combined  with  the 
dip  of  the  strata,  caused  the  superincumbent  hard  quartzose  beds, 
23  feet  thick,  to  form  the  base  of  the  precipice.    From  this  point  the 


Geology  of  the  South  of  Westmoreland.  555 

retrocession  must  have  proceeded  much  more  slowly  for  about  a  mile, 
or  to  the  Whirlpool,  where  a  small  fall  of  6  or  8  feet  still  marks  the 
place  of  the  highest  beds  of  the  sandstone.  After,  Mr.  Lyell  says, 
the  cataract  had  remained  nearly  stationary  for  ages  at  this  point,  it 
next  receded  more  rapidly  for  two  miles,  having  soft  red  marl  70  feet 
thick  to  erode  its  way  through ;  but  beds  of  greater  solidity,  con- 
sisting of  grey  and  mottled  sandstone  and  Protean  limestone,  amount- 
ing in  all  to  30  or  40  feet,  then  offered  a  greater  resistance,  and  con- 
tinued to  retard  the  backward  movements  of  the  Falls,  the  Protean 
limestone  occurring  at  the  base  of  the  present  precipice. 

Lastly,  the  author  offers  some  observations  respecting  the  future 
retrocession  of  the  Falls,  quoting  the  opinions  entertained  by 
Mr.  J.  Hall  (Report  for  1838)  on  the  effects  which  the  strata 
above  the  existing  cataract  will  have  on  the  progress  of  the  river, 
and  pointing  out  results  similar  to  those  given  by  Mr.  De  la  Beche 
in  his  '  Manual  of  Geology.'  But  all  predictions,  Mr.  Lyell  says, 
regarding  the  future  history  of  the  Falls  may  be  falsified  by  the 
disturbing  agency  of  man.  Already  a  small  portion  of  the  waters 
of  Lake  Erie  is  carried  off  to  supply  the  Welland  canal,  and  another 
canal  on  the  American  side  of  Niagara ;  and  numerous  mill-races 
have  been  projected  and  others  will  be  required  along  both  sides  of 
the  river,  as  the  population  and  wealth  of  the  country  increase. 
Many  cities  also,  situated  to  the  eastward  of  the  great  escarpment 
and  at  a  lower  level,  may  in  after  times  borrow  water  from  Lake 
Erie,  especially  as  the  continued  felling  of  the  forests  causes  streams 
which  were  formerly  constant  to  become  dry  in  summer;  and  it 
must  not  be  forgotten  that  Lake  Michigan  has  lately  been  made  by  a 
cutting  to  feed  the  Illinois  river,  and  that  whatever  quantity  of  water 
is  abstracted  from  the  upper  lakes  is  taken  away  from  the  Niagara. 

Feb.  2nd, — "  Sketch  of  the  Geology  of  the  South  of  Westmore- 
land."    By  Daniel  Sharpe,  Esq.,  F.G.S. 

The  object  of  this  communication,  the  author  says,  is  to  describe 
the  Silurian  rocks  and  the  old  red  sandstone  of  the  south  of  West- 
moreland, to  define  approximative^  their  geographical  boundaries, 
and  to  compare  their  lithological  structure  and  stratigraphical  phe- 
nomena with  the  equivalent  formations  previously  noticed  in  other 
parts  of  the  kingdom. 

The  author,  in  alluding  to  the  published  labours  of  those  who 
preceded  him  in  the  same  district,  mentions  the  memoir  of  Mr.  J. 
Phillips  on  a  group  of  slate  rocks  between  the  Lune  and  Wharf, 
Prof.  Sedgwick's  on  the  Cumbrian  mountains f,  Mr.  J.  G.  Mar- 
shall's on  a  section  between  the  Shap  granite  and  Casterton  Fell  J, 
and  Prof.  Sedgwick's  Geological  Map  of  Westmoreland ;  also  the 
abstract  of  his  memoirs  on  the  English  stratified  rocks  inferior  to 
the  old  red  sandstone  §. 

•  Geol.  Trans.,  2nd  Series,  vol.  hi.  part  i.  p.  1,  1829. 
t  Ibid,  vol.  iv.  part  i.  p.  47,  1835. 
%  Proceedings  of  British  Association  for  1839. 

§  Proceedings,  vol.  ii.  p.  675  [Phil.  Mag.  S.  3.  vol.  xiii.  p.  299.] ;  Athe- 
naeum, No.  736;    Proceedings,  vol.  hi.  p.  541. 


556  Geological  Society :  Mr.  D.  Sharpe  on  the 

The  different  formations  are  described  under  the  heads  of,— 
1 .  Coniston  Limestone ;  2.  Blue  Flagstone  Rock;  3.  Windermere 
Rocks  ;  4.  Ludlow  Rocks  ;  and  5.  Old  Red  Sandstone. 

1.  Coniston  Limestone. — This  calcareous  band,  which  has  been 
laid  down  in  great  detail  by  Prof.  Sedgwick,  was  adopted  by  Mr. 
Sharpe  as  the  base  of  his  inquiries.  It  usually  rests  upon  dark 
brown  shale,  and  consists,  in  its  lowest  part,  of  a  hard,  dark  blue,  slaty 
limestone,  from  fifty  to  sixty  feet  thick  at  Low  Wood ;  and  in  the 
upper,  of  thin  beds  of  dark  brown  shale,  alternating  with  others  of 
blue  limestone,  which  gradually  diminish  in  thickness,  and  totally 
disappear  towards  the  top  of  the  formation.  The  bottom  bed  of 
limestone  contains  very  few  organic  remains,  but  the  shales  and 
thinner  calcareous  bands  abound  with  casts.  A  list  of  fossils  given 
by  the  author  includes  fifteen  Silurian  species,  seven  of  which  be- 
long to  the  lower  Silurian  rocks  of  Mr.  Murchison ;  and  the  author 
places  the  Coniston  limestone  and  associated  shales  on  the  parallel 
of  that  division  of  the  Silurian  system,  but  without  attempting  to 
define  its  exact  relative  position.  Mr.  Marshall,  on  the  authority  of 
Mr.  J.  Sowerby,  places  the  Coniston  limestone  on  the  parallel  of 
the  Caradoc  limestone.  An  exact  account  of  the  strike  and  dip  of 
the  rock,  the  author  says,  will  be  found  in  Prof.  Sedgwick's  memoir, 
but  the  general  bearing  of  the  strike  of  the  beds  throughout  the 
western  part  of  their  course  is  stated  to  be  north-east,  though  on 
approaching  Shap  more  nearly  east  and  west ;  and  the  ordinary  dip 
is  stated  to  be  south-east,  with  an  inclination  rarely  less  than  30°, 
and  frequently  exceeding  60°. 

2.  Blue  Flagstone  Rock. — The  shales  of  the  last  deposit  pass  up- 
wards into  a  dark  blue  flagstone,  the  strike  of  which  is  parallel 
to  that  of  the  Coniston  limestone,  and  the  dip  is  conformable.  It 
is  stated  to  range  from  the  west  of  Coniston  by  the  village  of 
Torver,  the  head  of  Coniston  Lake,  also  south  of  the  Ambleside 
road  to  Low  Wray,  and  thence  from  the  east  side  of  Windermere, 
by  Trout  Beck  and  Kentmere,  to  the  neighbourhood  of  the  Shap 
granite.  The  faults  which  affected  the  Coniston  limestone  series 
extend  into  this  deposit.  No  organic  remains  were  found  by  the 
author,  but  he  is  of  opinion  that  their  absence  may  be  owing  to  the 
rearrangement  of  the  constituent  particles  of  the  rock  when  they 
assumed  the  slaty  structure. 

3.  Windermere  Rocks. — This  vast  series  of  beds,  to  which  Mr. 
Marshall  applied  the  name  of  Blawith  slate,  succeeds  conformably 
to  the  blue  flagstone,  and  is  arranged  by  the  author  into  three 
groups,  which  he  calls  the  lowest,  middle,  and  upper  divisions.  A 
line  drawn  from  Coniston  Water  Head  to  Lindale,  a  distance  of 
twelve  miles,  would  cross  the  beds  at  right  angles  to  the  strike  ;  and 
though  the  same  strata  are,  according  to  the  author,  frequently  re- 
peated in  a  succession  of  parallel  anticlinal  ridges,  yet  he  is  of  opinion 
that  the  total  thickness  of  the  formation  exceeds  5000  feet. 

3a.  Lowest  Division. — This  portion  of  the  Windermere  rocks  con- 
sists of  gray  schistose  grits  and  argillaceous  slates,  containing  thin 
beds  of  limestone  on  the  banks  of  Coniston  Lake.     The  strata  are 


Geology  of  the  South  of  Westmoreland.  557 

stated  to  be  much  affected  by  cleavage  lines.  The  usual  strike  of 
the  beds  at  the  foot  of  Coniston  is  said  to  be  north-east,  but  great 
variations  are  shown  to  occur  in  other  portions  of  the  district,  in  con- 
sequence of  anticlinal  ridges  which  range  north  and  south.  The 
boundary  between  this  division  and  the  middle  one  passes  from  the 
foot  of  Coniston  Water  to  the  ferry  on  Windermere,  and  thence  by 
the  foot  of  the  valley  of  Kentmere,  across  Long  Sleddale  at  Murth- 
waite  Crag,  south  of  Tebay  Fell,  Langdale  Fell  and  Ravenstone  Fell, 
to  Rathay  Bridge,  but  it  is  much  affected  by  dislocations.  The  general 
range  of  the  division,  Mr.  Sharpe  states,  may  be  traced  by  the  grits 
and  slates  forming  a  series  of  bold  hills  which  stand  out  in  relief 
above  the  tame  rounded  masses  of  the  argillaceous  schists  of  the 
middle  division. 

The  author  alludes  to  a  band  of  calcareous  slates  shown  by  Prof. 
Sedgwick  to  range  from  Blawith  to  the  south-west,  but  he  states  that 
he  failed  to  find  its  eastern  continuation  ;  he  alludes  likewise  to  Mr. 
Marshall's  account  of  having  found  lower  Silurian  fossils  in  it ;  and 
he  is  induced,  on  this  account,  to  conceive  that  the  calcareous  band 
may  form  the  uppermost  portion  of  the  lower  Silurian  rocks.  The 
lowest  division  of  the  Windermere  series  is  stated  to  be  well  exposed 
on  the  shores  of  Coniston  Lake. 

3b.  Middle  Division. — This  deposit  consists  of  hard  argillaceous 
rocks,  usually  striped  or  banded  gray,  blue,  or  white,  and  sometimes 
brown ;  it  contains  also  beds  of  soft  shale  and  hard  grits  similar  to 
those  of  the  lowest  division.  On  the  west  side  of  Windermere  the 
usual  strike  is  north-east,  but  to  the  eastward  of  the  lake  the  strata 
are  stated  to  be  thrown  into  great  confusion  by  faults  ranging  north 
and  south.  The  boundary  between  this  and  the  upper  division  is 
drawn  by  the  author  from  Newby  Bridge  to  Witherslack  ;  but  from 
Whitborrow  to  the  Lune,  the  southern  edge  of  the  deposit  is  over- 
laid unconformably  by  various  rocks  of  more  modern  date.  East  of 
the  Lune  the  Windermere  rocks  are  stated  to  be  less  concealed  by 
other  formations,  the  southern  boundary  ranging  from  a  little  east  of 
Barbon  to  Barbon  Fell  House,  where  it  is  again  overlaid  by  carbo- 
niferous limestone.  The  only  traces  of  organic  remains  mentioned 
by  the  author  are  some  crushed  specimens,  one  of  which  he  considers 
to  be  a  Phragmoceras. 

3c.  Upper  Division. — This  division  consists  of  hard,  compact, 
purplish  greywacke,  little  affected  by  cleavage,  and  can  be  distin- 
guished from  the  Ludlow  rocks  only  by  the  absence  of  fossils.  The 
strata  are  greatly  disturbed  by  north  and  south  anticlinal  faults. 
The  division  is  exposed  in  only  two  limited  districts ;  one  south  of 
Windermere,  and  the  other  east  of  the  Lune,  constituting  Barbon 
Beacon  and  the  western  end  of  Casterton  Fell,  all  the  intermediate 
district  being  occupied  by  newer  formations. 

4.  Ludlow  Rocks. — This  series  rests,  the  author  says,  unconform- 
ably on  the  Windermere  beds  ;  but  the  want  of  conformity  is  stated 
to  be  inferred,  not  from  the  usual  evidence  of  irregular  deposition  at 
the  passage  beds,  but  from  the  relative  position  of  the  two  formations, 
the  Ludlow  rocks  resting,  in.  different  places,  on  the  middle  and 


558  Geological  Society:  Mr.  D.  Sharpe  on  the 

upper  divisions  of  the  Windermere  series.  The  deposit  is  composed 
of  hard,  purplish  gray,  argillaceous  strata,  and  though  intersected  hy 
several  cleavage  plains,  does  not  possess  a  slaty  structure.  The  lines 
of  stratification  are  usually  well-marked  by  thin  rotten  layers  full 
of  casts  of  shells,  the  intermediate  portions  being  devoid  of  organic 
remains.  The  range  of  the  Ludlow  rocks,  as  limited  by  the  author 
to  beds  which  contain  fossils,  and  commencing  west  of  Kendal  Fell, 
is  stated  to  be  a  narrow  strip  at  the  base  of  Underbarrow  Scar ;  and 
on  the  east  of  Kendal  Fell,  is  a  patch  on  the  Tenter  Fell,  north-west 
of  Kendal.  In  the  valley  of  the  Kent,  the  Ludlow  rocks  are  con- 
cealed by  newer  deposits  ;  but  east  of  the  valley  they  constitute  the 
high  anticlinal  ridge  of  Benson  Knot  and  Helme,  the  top  of  the  latter, 
however,  being  old  red  sandstone  ;  they  occupy  also  all  the  country 
thence  to  the  Lune,  except  the  highest  point  of  Lupton  Fell,  where 
the  Windermere  rocks  are  brought  to  the  surface,  being  bounded  on 
the  west,  south,  and  east  by  mountain  limestone  or  old  red  sandstone. 
The  usual  strike  of  the  beds  is  said  by  the  author  to  be  north  and  south, 
and  the  dip  either  east  or  west,  the  strike  conforming  to  the  direction 
of  the  principal  faults.  The  chief  anticlinal  north  and  south  ridges 
are  stated  to  be  Benson  Knot,  Helme,  Old  Hutton  Common,  and 
Lupton  Fell :  several  east  and  west  faults  are  likewise  mentioned 
in  the  paper  ;  as  in  Lambrigg  Park  and  Fell,  in  Mansergh  Common, 
west  of  Lunesdale,  and  at  Old  Town. 

A  gradual  passage  from  the  upper  beds  of  the  Ludlow  rocks  into 
the  tilestone  of  the  old  red  sandstone  is  exposed  at  the  top  of  Helme 
at  Old  Town  and  the  southern  part  of  Mansergh  Common ;  and 
the  author  is  induced  to  infer,  from  eleven  of  the  twenty-five 
species  found  in  the  bottom  beds  of  Herefordshire  occurring  also 
in  the  upper  Ludlow  rocks  of  that  district,  and  from  seven  of  the 
remaining  fourteen  species  occurring  low  in  the  Ludlow  rocks  of 
Westmoreland,  that  the  beds  which  have  been  considered  to  form 
the  bottom  of  the  old  red  sandstone  ought  to  be  included  in  the  Silu- 
rian system.  A  further  argument  in  support  of  this  arrangement  is 
drawn  from  the  fact,  that  where  the  old  red  sandstone  rests  on  the 
Windermere  rocks  these  doubtful  beds  are  wanting,  the  shells  being 
found  only  where  the  Ludlow  rock  occurs. 

A  list  of  thirty-four  species  of  fossils  is  given  in  the  paper,  con- 
sisting almost  solely  of  Ludlow  Testacea  figured  in  Mr.  Murchison's 
work,  but  the  author  does  not  state  positively  to  what  portion  of 
the  Ludlow  series  the  Westmoreland  beds  ought  to  be  assigned. 

5 .  Old  Red  Sandstone. — The  following  distinct  districts,  composed 
of  old  red  sandstone,  occur  within  the  area  described  by  the  author  : 
(a.)  that  in  the  valley  of  the  Lune  and  the  neighbourhood  of  Kirkby 
Lonsdale ;  (b.)  those  near  Kendal  and  in  the  valleys  of  the  Kent, 
Sprint,  and  Mint ;  and  (c.)  that  near  Shap  and  Tebay. 

5a.  To  the  old  red  of  the  valley  of  the  Lune,  above  Kirkby  Lons- 
dale, the  author  assigns  the  bed  of  loose  conglomerate  and  red  clay, 
which  he  says  dips  under  the  scar  limestone  of  Casterton,  the  lime- 
stone being  inclined  to  the  south-east  at  an  angle  of  30°,  and  the 
conglomerate  to  the  east  by  north  at  an  angle  of  25°,    The  want  of 


Geology  of  the  South  of  Westmoreland.  559 

conformity  is  stated  to  be  more  manifest  to  the  westward  ;  for  where 
the  limestone  bends  round  by  Kirkby  Lonsdale  bridge  it  dips  25°  or 
30°  to  the  south-south-east ;  at  Catshole  quarry  the  strata  are  arched 
with  a  north-west  strike ;  at  Hollin  Hall  quarry  the  dip  is  south-west 
30°,  and  at  Teamside  40°  south-east ;  but  the  old  red  sandstone  dips 
throughout,  as  far  as  the  beds  can  be  seen,  to  the  east.  At  Caster- 
ton  the  loose  conglomerate  is  100  feet  thick,  and  passes  downwards 
into  red  marl,  occasionally  mottled  blue,  and  estimated  to  be  fifty  feet 
thick.  This  marl  rests  on  alternating  beds  of  red  marl  and  red  sand- 
stone, beneath  which  is  a  considerable  deposit  of  dark  red  tilestone 
and  light- coloured  sandstone,  forming  the  passage  beds  into  the  Lud- 
low rocks.  The  total  thickness  is  estimated  at  1000  feet.  To  the 
north  of  the  Casterton  fault,  the  lower  beds  of  the  old  red  sandstone 
arc  stated  to  be  raised  up  and  exposed,  far  to  the  eastward  of  their 
position  below  Casterton  ;  and  above  this  spot  the  right  bank  of  the 
river  is  said  to  be  composed  of  the  lowest  beds  of  the  tilestones  and 
the  passage  beds  into  the  Ludlow  rock,  but  the  left  bank  to  consist 
of  tilestones  and  red  sandstones.  The  dip  is  east,  at  an  angle  of  25°. 
Mr.  Sharpe  also  assigns  to  the  old  red  sandstone,  but  not  definitive- 
ly, the  bed  of  brown  gravel,  or  of  brown  clay  full  of  pebbles,  which 
covers  the  whole  of  the  valley  of  the  Lune  to  its  junction  with  the 
Rathay,  and  up  that  valley  nearly  to  Sedbcrgh.  It  forms  a  line  of 
low  hills  on  each  side  of  the  Lune,  resting  on  the  northern  edge  of 
the  tilestones  above  Barbon  Beck,  and  conceals  the  junction  of  the 
Ludlow  rocks  on  the  right  of  the  Lune  with  the  Windermere  rocks 
on  the  left  of  that  river. 

5b.  Several  limited  patches  of  old  red  sandstone  occur  in  the 
neighbourhood  of  Kendal,  the  remnants,  in  the  author's  opinion,  of  a 
once  continuous  mass.  They  consist,  near  Kirkby  Lonsdale,  of  red 
conglomerates,  red  marls,  and  red  and  light-coloured  sandstones, 
with  tilestones,  which  pass  downwards  into  the  Ludlow  rocks. 
Some  of  these  patches,  as  on  the  top  of  Helme  and  at  Monument 
Hill,  two  miles  north-east  of  Kendal,  have  been  raised  to  a  consider- 
ably higher  level  than  the  rest  of  the  formation.  Three  miles  above 
Kendal  the  old  red  sandstone  is  well- exposed  on  the  banks  of  the 
Sprint,  consisting  of 

Loose  conglomerate    60  to  80  feet. 

Red  marl 50    ... 

Thin-bedded  red  sandstone 30    ... 

The  strike  of  the  beds  is  north  by  west,  and  the  dip  east  by  north 
10°,  and  they  are  unconformable  to  the  adjacent  older  rocks.  Similar 
beds  are  slightly  exposed  in  the  banks  of  the  Mint,  near  Lavrock 
Bridge,  striking  east,  and  dipping  5°  north,  a  bearing  different  from 
that  of  all  the  neighbouring  rocks.  They  are  separated  from  a  more 
extensive  patch  about  Greyrigg  by  an  anticlinal  ridge  of  the  middle 
division  of  the  Windermere  rocks,  but  they  cover  a  considerable  area 
capped  by  nearly  horizontal  beds  of  mountain  limestone.  Around 
Kendal  is  another  doubtful  deposit  of  brown  gravel,  and  the  castle 
stands  upon  it. 

5c.  Shap  and  Tebay.— The  course  of  the  Birkbeck,  from  its  rise 


560  Geological  Society :  Mr.  D.  Sharpe  on  the 

above  Shap  Wells  to  its  junction  with  the  Lune  at  Tebay,  intersects 
a  deposit  of  old  red  sandstone,  and  the  same  deposit  extends  for 
some  distance  eastward  up  the  valley  of  the  Lune.  It  consists  of 
the  usual  triple  division,  but  the  passage  beds  into  the  Ludlow  rocks 
are  entirely  wanting,  and  the  lower  beds  thin  out  in  ascending  the 
valley  from  Tebay.  It  rests  on  the  lowest  portion  of  the  Winder- 
mere series.  The  dip  is  only  5°  or  10°  to  the  north-east.  On  the 
opposite  side  of  the  ridge  which  separates  the  Lune  from  the  Low- 
ther,  the  old  red  again  occurs  in  the  valley  of  the  latter  river,  the 
intervening  ridge  being  occupied  by  masses  of  the  doubtful  brown 
gravel.  Throughout  this  district  the  lowest  beds  of  the  mountain  or 
scar  limestone  rest  conformably  on  the  old  red  sandstone. 

General  Remarks ;  or  comparison  of  the  Westmoreland  strata  with 
the  equivalents  in  other  parts  of  the  kingdom. — The  triple  division 
of  the  Westmoreland  old  red  sandstone,  the  author  says,  agrees  re- 
markably with  that  of  Herefordshire,  as  already  stated  by  Mr.  J. 
Phillips  in  his  work  on  the  Fossils  of  Devonshire ;  the  only  differ- 
ences being  the  disaggregated  state  of  the  conglomerates,  and  the 
absence  of  the  cornstones  as  well  as  of  the  Ichthyolites.  The  gradual 
passage  from  the  bottom  of  the  old  red  sandstone  into  the  Ludlow 
rocks  also  coincides  with  the  phenomena  described  in  Herefordshire 
by  Mr.  Murchison.  The  Ludlow  rocks  of  Westmoreland  will  also 
bear  comparison  with  those  of  the  border  counties  of  England  and 
Wales  ;  but,  owing  to  the  absence  of  the  Aymestry  limestone,  it  is 
not  possible,  the  author  states,  to  fix  the  exact  relative  position  of 
the  former  with  respect  to  the  latter,  but  he  says  that  they  exactly 
agree  with  the  upper  division  of  the  upper  Silurian  rocks  of  Den- 
bighshire, as  described  by  the  late  Mr.  Bowman*.  With  respect 
to  the  Windermere  series,  the  author  likewise  hesitates  to  place  it 
on  an  exact  parallel  with  any  of  the  subdivisions  of  the  Silurian  as 
described  in  Mr.  Murchison's  work,  but  he  states  that  it  precisely 
agrees  in  part  with  lower  divisions  of  the  Denbighshire  upper  Silu- 
rian rocks,  both  in  general  characters  and  the  details  of  the  com- 
ponent strata.  The  Coniston  limestone  Mr.  Sharpe,  as  already 
stated,  prefers  to  consider  as  a  lower  Silurian  deposit,  than  as  the 
equivalent  of  any  one  of  the  members  of  that  series  of  rocks. 

The  author  then  enters  upon  the  inquiry  of  the  principal  epochs 
of  disturbance  and  elevation  of  the  Westmoreland  rocks ;  and  he 
shows,  1st,  that  the  earliest  period  of  disturbance  was  connected 
with  the  outburst  of  the  Shap  granite  ;  inferring,  from  the  conform- 
ity of  the  Windermere  rocks  with  the  Coniston  limestone,  that  all 
these  series  were  deposited  before  the  outbreak  of  the  granite  ;  2nd, 
that  the  old  red  sandstone  resting  horizontally  on  the  elevated  rocks 
of  Shap  Fell,  proves  that  this  formation  was  accumulated  after  the 
disturbance  consequent  upon  the  protrusion  of  the  granite;  3rd, 
that  all  the  faults  which  affect  the  old  red  sandstone,  or  any  newer 
formation,  are  more  modern  than  the  outburst  of  the  granite. 
Although  difficulties  attend  the  fixing  of  the  age  of  the  Ludlow  rocks 
relative  to  the  outburst  of  the  granite,  on  account  of  the  complicated 
*  Athenreum,  No.  719,  Aug.  7,  1841. 


Geology  of  the  South  of  Westmoreland.  561 

irregularity  of  the  position  of  the  former,  yet  the  author  thinks,  that 
from  the  want  of  conformity  of  the  Ludlow  rocks  to  the  Windermere, 
and  from  the  faults  which  traverse  them  extending  into  the  old  red 
sandstone,  that  they  were  deposited  subsequently  to  the  protrusion 
of  the  granite.  Having  thus  defined  the  limit  of  that  event,  Mr. 
Sharpe  proceeds  to  show  its  effects.  In  the  south  of  Westmoreland, 
he  says,  it  threw  into  a  high  angle  the  strata  of  Coniston  limestone 
and  Windermere  schists,  and  produced  the  great  east  and  west  faults 
around  Coniston  and  Windermere,  as  well  as  in  Middleton  and  Cas- 
terton  Fells ;  likewise  the  dislocations  of  the  Coniston  limestone, 
with  their  prolongations  in  the  valleys  of  Coniston,  Esthwaite,  Win- 
dermere, Kentmere,  Long  Sleddale,  &c,  which  are  not  continued 
into  the  Ludlow  rocks.  These  valleys,  or  lines  of  cracks,  Mr.  Sharpe 
says,  are  quite  distinct  in  character  from  the  north  and  south  syn- 
clinal valleys  in  those  rocks ;  he  is  also  of  opinion  that  the  valley 
of  the  Lune  had  a  similar  origin,  but  the  older  rocks  being  con- 
cealed by  newer  deposits,  its  resemblance  to  the  other  valleys  is  less 
complete. 

Mr.  Sharpe  did  not  observe  any  proof  of  the  Ludlow  rocks  having 
been  disturbed  anterior  to  the  deposition  of  the  old  red  sandstone, 
but,  he  says,  there  is  abundant  evidence  of  both  those  formations 
having  been  dislocated  before  the  accumulation  of  the  mountain 
limestone,  as  the  limestone  of  Kendal  Fell  rests  in  a  nearly  horizontal 
position  upon  the  upraised  edges  of  an  anticlinal  ridge  of  Ludlow 
rocks,  from  which  a  covering  of  old  red  sandstone  is  considered  to 
have  been  partially  denudated  :  the  anomalous  manner  in  which  the 
limestone  overlies  the  old  red  sandstone  of  Kirkby  Lonsdale  is,  he 
sa)'S,  another  instance.  The  principal  north  and  south  faults  of  the 
Ludlow  rocks,  and  a  portion  of  the  Windermere  schist,  between 
Windermere  and  the  Lune,  are,  however,  considered  by  the  author 
to  be  of  later  origin  than  the  mountain  limestone,  and  he  particularly 
refers  to  the  disturbances  at  Natlands,  Farleton  Knot,  Hutton  Roof, 
Lupton  Fell,  Witherslack,  Whitbarrow  and  Kendal  Fell.  Lastly, 
the  author  calls  attention  to  the  successive  elevation  of  hills  in  one 
direction  by  forces  acting  at  different  periods  as  a  phaenomenon  which 
has  not  received  the  thought  it  deserves  ;  and  he  points  out  as  an 
instance  the  Windermere  schists  forming  the  high  chain  of  Middle- 
ton  and  Casterton  Fells,  which  chains,  he  says,  were  elevated  from 
the  north  at  the  period  of  the  eruption  of  the  Shap  granite,  nearly  as 
they  are  at  present,  for  they  formed,  he  states,  the  boundary  of  the 
great  hollow  in  which  the  Ludlow  rocks  were  deposited ;  and  the 
great  faults  which  cross  the  Fells  in  an  east  and  west  direction  were, 
he  is  of  opinion,  formed  at  the  same  period,  the  mountain  limestone 
not  having  been  broken  through  by  the  faults  in  which  the  Rathay, 
the  Dee,  and  the  Barbon  traverse  the  chain :  yet  this  chain  of  hills 
has  been  elevated,  he  adds,  in  the  same  north  and  south  direction 
subsequently  to  the  deposition  of  the  mountain  limestone,  the  whole 
band  of  limestone  resting  upon  their  eastern  flanks  having  been 
thrown  up  to  a  high  angle,  and  in  some  places  much  disturbed. 

Phil.  Mag.  S.  a .  No.  1 4 1 .  SuppL  Vol.  2 1 .  2  P 


5G"2 


INDEX  to  VOL.  XXI. 


ACARI,  production  of,  61,  64,  312. 

Acids  : — anisic,  16 ;  anisonitric,  17  ;  me- 

lasinic,  ib. ;  umbellic,  ib. ;  badianic,  18; 

cyminic,    ib. ;      cumino-cyminic,   ib. ; 

uvic,  ib. ;  sulpho-hyposulphurous,  20 ; 

sulphurous,21;  oxichloric,  157;  stearo- 

phanic,  161 ;  formic, 236;  laurostcaric, 

238 ;  ferrocyanic,  325 ;  hippuric,  382 ; 

phosphoric,  379 ;  opianic,  449 ;  indi- 

gotic,  450 ;  salicylic,  ib. 
Addison,  (W.)  on  the  mode  of  formation 

of  the  air-cells  of  the  lungs,  51 . 
Agriculture,  use  of  sulphate  of  ammonia 

in,  488. 
Air-cells  of  the  lungs,  on  the  mode  of 

formation  of  the,  51. 
Aluminates,  on  the  analysis  of  native,  78. 
American  Philosophical  Society,  proceed- 
ings of  the,  150. 
Ammonia,  use  of  the  sulphate  of,  in  agri- 
culture, 488. 
Ammonites,  on  the  mouths  of,  546. 
Analytic  geometry,  on  a  theorem  in,  1 76. 
Anatase,  on  the  optical  constants  of,  277. 
Andesine,  notice  respecting,  74. 
Animals,  minute  anatomy  of,  107,  168, 

241. 
Anisic  acid,  16. 
Antimony,  presence  of  in  arsenious  acid, 

238. 
Apjohn  (Dr.  J.)  on  the  force  of  aqueous 

vapour  within  the  range  of  atmospheric 

pressure,  389. 
Ashby  (J.  E.)  on  tbe  use  of  iron  wire  for 

secondary  electro-magnetic  coils,  411. 
Atmosphere,  on  the  transparency  of  the, 

223. 
Atmospheric   pressure,   influence  of  the 

moon  on,  227. 
Atomic  weights,  revision  of  the,  279, 409. 
Aurora  borealis,  remarks  on,  52. 
Awdejew   (M.)    on   glucinium    and   its 

compounds,  284. 
Baily  (F.)  on  the  mean  density  of  the 

earth,  111. 
Balmain  (W.  H.)  on  a  new  process  for 

preparing  oxygen,  42 ;  on  compounds 

of  boron  and  silicon  with  nitrogen  and 

certain  metals,  270. 
Barometrical  observations,  222. 
Barry  (Dr.  M.)  on  fibre,  220;  on  the 

structure  of  muscle,  351. 


Bases,  formula  for  eliminating  the  weights 
of  mixed,  188. 

Batteries,  constant,  employment  of  ni- 
trate of  soda  for,  61. 

Battery,  on  a  new  form  of,  311. 

Becquerel  (E.)  on  the  constant  voltaic 
battery,  329 ;  on  the  electro-chemical 
properties  of  simple  bodies,  and  on  their 
application  to  the  arts,  404. 

Birds,  on  the  structure  of  fibrinous  exu- 
dations in,  244. 

Blood-corpuscles,  on  the  nuclei  of  the,107. 

Blood,  on  the  pus-like  globules  of  the,  168. 

Bone-bed  in  the  lower  lias  near  Tewkes- 
bury, 540. 

Booth  (J.)  on  the  rectification  and  qua- 
drature of  the  spherical  ellipse,  54 ;  on 
a  theorem  in  analytic  geometry,  1 76, 
444. 

Bowerbank  (J.  S.)  on  organic  tissues  in 
the  bony  structure  of  the  Corallidae,  53. 

Bremicker's  comet,  observations  on,  59. 

Brewing,  observations  on,  317. 

Brewster's  (Sir  D.)  deductions  from  the 
hourly  observations  at  Leith,  remarks 
on,  43 ;  on  the  absorption  of  light  and 
the  colours  of  thin  plates,  208. 

Brodie  (Rev.  P.  B.)  on  the  occurrence  of 
plants  in  the  plastic  clay,  546. 

Budan's  criterion  for  the  imaginary  roots, 
on  the  extension  of,  96. 

Cadmium,  on  some  salts  of,  355. 

Cahours  (M.)  on  the  oils  of  fennel,  anise 
and  star-anise,  15. 

Calomel,  non-conversion  of,  into  sublimate 
by  the  alkaline  chlorides,  411. 

Calvert  (F.  C.)  on  the  preparation  of 
quina  and  cinchonia,  171. 

Cambridge  Philosophical  Society,  pro- 
ceedings of  the,  485. 

Cerium  and  its  salts,  on,  278. 

Chalk  of  the  Brighton  chffs,  analysis  of, 
379. 

Challis  (Rev.  J.)  on  the  rectilinear  mo- 
tion of  fluids,  101,  297,  423. 

Chemical  rays,  on  a  new  class  of,  453. 

Chemical  Society,  proceedings  of  the,  313, 
378. 

Chemistry : — oils  of  fennel,  anise  and 
star-anise,  15  ;  action  of  chromic  acid 
on  volatile  oils,  17 ;  action  of  hydrate 
of  potassa  on  hydro-benzamide,    18  ; 


INDEX. 


5G3 


salts  of  uvic  acid,  18;  nicotin,  19;  a 
new  acid  of  sulphur,  ib. ;  double  hypo- 
sulphites, 20 ;  on  the  basic  sulphate  of 
mercury,  35 ;  new  process  for  prepa- 
ring oxygen,  42 ;  compounds  of  palla- 
dium and  platinum,  50 ;  alloys  of  cop- 
per with  tin  and  zinc,  66  ;  red  molyb- 
date  of  lead,  73;  method  of  distinguish- 
ing between  nitrates  and  chlorates,  74 ; 
sulphur  in  plants,  74  ;  action  of  salts 
on  plants,  75  ;  analysis  of  native  alu- 
minates,  78  ;  scientific  labours  of  Rich- 
ter,  81 ;  hyponitrite  of  methyl,  150, 
152;  ultramarine,  156;  oxichloric  acid, 
157 ;  action  of  water  on  lead,  158  ; 
stearophanic  acid  and  salts,  161 ;  pal- 
mitine,  167 ;  laurostearic  acid,  1 67, 
237 ;  preparations  of  quina  and  cincho- 
nia,  171 ;  general  formula  for  elimi- 
nating the  weights  of  mixed  bases,  188; 
biniodide  of  mercury,  192  ;  a  new  ox- 
alate of  chromium  and  potash,  197 ; 
curcumine,  233  ;  solubility  of  the  in- 
soluble salts  of  the  alkaline  earths  in 
chloride  of  sodium,  236 ;  production 
of  formic  acid  in  oil  of  turpentine,  ib. ; 
precipitation  of  certain  salts  by  excess 
of  acids,  ib.  ;  solubility  of  salts  in  per- 
nitrate  of  mercury,  237 ;  antimony  in 
arsenious  acid,  238 ;  didymium,  239, 
278  ;  compounds  of  boron  and  silicon 
with  nitrogen,  270;  cerium  and  its 
salts,  278  ;  atomic  weights  of  chlorine 
arid  zinc,  279 ;  hyposulphites,  ib. ; 
sulphocyanurets,  280;  sulphates  of 
alumina  and  chromium,  281 ;  chro- 
mates,  283 ;  glucinium  and  its  com- 
pounds, 284 ;  action  of  water  on  sul- 
phurets  and  haloid  salts,  285  ;  agency 
of  caloric  in  modifying  the  state  of 
aggregation  of  bodies,  313;  decomposi- 
tion of  oxalic  methylic  aether  by  alco- 
hol, 315;  on  brewing,  317  ;  bichloride 
of  hydrogen,  320  ;  action  of  chlorides 
upon  protochloride  of  mercury,  ib. ; 
cinchovatina,  323 ;  preparation  of 
pure  potash  and  soda,  324 ;  detection 
of  iodine  in  bromides,  ib. ;  ferrocyanic 
acid  and  ferridcyanideof  potassium, 325, 
326 ;  iodide  of  mercury,  336  ;  artificial 
yeast,  352 ;  salts  of  cadmium,  355 ; 
analysis  of  the  chalk  of  the  Brighton 
cliffs,  379;  chromate  of  manganese, 
381 ;  preparation  of  hippuric  acid,  382; 
Prussian  blue,  384  ;  South  Sea  Guano, 
385  ;  artificial  uranite,  387  ;  atomic 
weight  of  elements,  409 ;  conversion 
of  calomel  into  sublimate,  411  ;  me- 
thod of  distinguishing  zinc  from  man- 
ganese, 412  ;  determination  of  nitro- 
gen, ib. ;  new  salt  of  soda  and  oxide 
of  platina,  413  ;    conia,  414  ;  hema- 


toxylin, 446 ;  opianic  acid,  449 ; 
quinoiline,  ib. ;  iudigotic  acid,  450 ; 
compounds  of  sugar  with  bases,  451  ; 
plumbo-sulphate  of  ammonia,  452 ; 
use  of  sulphate  of  ammonia  in  agricul- 
ture, 488  ;  test  for  vegetable  alkalies, 
489 ;  decomposition  by  fermentation 
of  vegetable  alkalies,  490;  pepsin, 
491  ;  action  of  chlorides  on  mercurial 
compounds,  492;  new  mode  of  form- 
ing ammonia,  495. 

Chlorite,  analysis  of,  76. 

Christie  (J.  It.)  on  the  extension  of  Bu- 
dan's  criterion  for  the  imaginary  roots, 
96. 

Christison  (Prof.)  on  the  action  of  water 
on  lead,  158. 

Chromates,  observations  on  some,  283. 

Chromic  acid,  action  of,  on  volatile  oil, 
17. 

Chromium,  on  a  new  oxalate  of,  197,  201 . 

Cinchonia  and  quina,  on  the  preparation 
of,  171. 

Cinchovatina,  a  new  vegetable  alkali,  323. 

Clark  (Prof.)  on  a  new  gas  burner,  384. 

Cock  (W.  J.)  on  the  production  of  artifi- 
cial uranite,  387. 

Colours,  vegetable,  on  the  action  of  the 
rays  of  the  solar  spectrum  on,  225. 

Colthurst  (J.)  on  contortions  and  faults 
produced  in  strata,  544. 

Conchyliometry,  researches  in,  300. 

Conia,  on  the  composition  of,  414. 

Copper,  properties  of  the  alloys  of,  with 
tin  and  zinc,  66. 

Corallidse,  on  organic  tissues  in  the  bony 
structure  of,  53. 

Corals  in  a  conglomerate  at  Malvern,  288. 

Cornwall,  on  earthquakes  in,  153. 

Croft  (H.)  on  a  new  oxalate  of  chromium 
and  potash,  197  ;  on  some  salts  of  cad- 
mium, 355  ;  on  the  decomposition  of 
oxalic  methylic  aether  by  alcohol,  315. 

Croft  and  Francis's  notices  of  the  inves- 
tigations of  continental  chemists,  15, 
278,  446. 

Crombie  (Ch.)  on  the  solar  eclipse  of  July 
18,  1841,  57. 

Crosse  (A.)  on  the  transfer  of  mineral  sub- 
stances through  fluids  by  electric 
agency,  64. 

Crystalline  reflexion  and  refraction,  on 
the  dynamical  theory  of,  228. 

Crystals,  on  the  optic  axes,  and  axes  of 
elasticity  of  biaxal,  293. 

Curcumine,  preparation  of,  233. 

Currents  produced  by  the  induction  of 
electric  currents,  observations  on  the, 
497. 

Cycle  of  eighteen  years,  reviewed,  69. 

Daguerreotype,  426. 

Daniell  (J.  F.)  on  voltaic  combinations, 
2  P  2 


564 


INDEX. 


54  ;  on  the  voltaic  battery,  329,  333, 
421. 
Darwin  (C.)  on  the  effects  produced  by 
the  ancient  glaciers,  and  on  the  boulders 
transported  by  ice,  180. 

Davies  (T.  S.)  on  Pascal's  mystic  hexa- 
gram, 37  ;  on  the  employment  of  po- 
lar coordinates  in  the  equation  of  a 
straight  line,  190. 

De  la  Rue  (W.)  on  the  agency  of  caloric 
in  modifying  the  state  of  aggregation 
of  the  molecules  of  bodies,  3l3. 

De  Morgan  (Prof.  A.)  on  Fcrnel's  mea- 
sure of  a  degree,  22. 

Density,  mean,  of  the  earth,  111. 

Devonian  system,  on  the  position  of  the 
Cornish  killas  in  the,  25. 

Dew-point,  influence  of  the,  on  vegeta- 
bles, 1. 

Dialytic  method  of  elimination,  on  the, 
534. 

Didvmium,  description  of  the  new  metal, 
239. 

Dioptase,  on  the  optical  constants  of,  277. 

Dove  (Prof.),  experiments  in  magneto- 
electricity,  33. 

Drach  (S.  M.)  on  Sir  D.  Brewster's  de- 
ductions from  the  hourly  observations 
at  Leith,  43 ;  on  the  aggregate  mass 
of  the  binary  star,  61  Cygni,  528. 

Draper  (Dr.  J.  W.)  on  certain  spectral 
appearances,  and  on  the  discovery  of 
latent  light,  348;  on  a  class  of  chemical 
ravs  analogous  to  the  rays  of  dark  heat, 
453. 

Dufrenoy  (M.)  on  Greenovite,  246. 

Earnshaw  (S.)  on  the  motion  of  luminous 
waves  in  an  elastic  medium,  46 ;  on 
the  theory  of  the  dispersion  of  light, 
122,  217,  340,  437. 

Earth,  on  the  mean  density  of  the,  111. 

Earthquakes  in  Cornwall,  153. 

Eclipse,  solar,  of  July  18, 1841,  on  the,  57. 

Electrical  Society  of  London,  proceedings 
of  the,  61,310,  404,  484. 

Electricity,  experiments  in,  33 ;  on  the 
transfer  of  mineral  substances  through 
fluids,  by,  64. 

Electro-magnetic  coils,  use  of  iron  wire 
for,  411. 

Electro-tint,  remarks  on,  62. 

Electrotype  manipulation,  61. 

Elements,  atomic  weights  of  some,  409. 

Elevation  and  denudation  of  the  district 
of  the  lakes  of  Cumberland  and  West- 
moreland, 468, 

Ellipse,  on  the  rectification  and  quadra- 
ture of  the  spherical,  54. 

Eisner  (M.)  on  the  blue  colour  of  ultra- 
marine, 156. 

Embryology,  on  the  progress  of,  337. 

Erdmann  (M.)  on  haematoxylin,  446. 


Everest  (Rev.  R.),  geological  observations 

on  the  Himalaya  mountains,  366. 
Ewart  (P.),  notice  of  the  late,  327. 
Farquharson  (Rev.  J.)  on  a  remarkable 

aurora  borealis,  52. 
Femel's  measure  of  a  degree,  remarks 

on,  22. 
Ferrocyanic  acid,  anhydrous  preparation 
of,  325. 

Fibre,  observations  on,  220. 

Fibrine,  on  the  structure  of,  109,  171, 
241. 

Fielding  (G.  H.)  on  the  causes  of  the  in- 
fluenza, 52. 

Fisher  (Prof.)  on  the  development  of  the 
spinal  ganglia,  and  on  malformations 
of  the  nervous  system,  485. 

Fluid  motion,  remarks  on,  29,  101,  297, 
423. 

Forbes  (J.  D.)  on  the  transparency  of 
the  atmosphere,  and  the  law  of  extinc- 
tion of  the  solar  rays  in  passing  through 
it,  223. 

Fossil  bones  found  on  a  raised  beach  near 
Plymouth,  notice  of,  543. 

Fownes  (Dr.  G.)  on  the  preparation  of 
artificial  yeast,  352  ;  on  the  prepara- 
tion of  hippuric  acid,  382  ;  on  South 
Sea  guano,  385. 

Francis  and  Croft's  notices  of  the  investi- 
gations of  continental  chemists,  15, 
278,  446. 

Francis  (Dr.  W.)  on  the  fruit  of  Meni- 
spermum  Cocculus,  and  on  stearophanic 
acid  and  its  salts,  161. 

Freezing  cavern,  observations  on  a,  358, 
362. 

Frend  (Mr.),  notice  of  the  late,  510. 

Fresenius  (R.)  on  the  salts  of  uvic  acid,  1 8. 

Ganglia,  on  the  development  of  the  spinal, 
and  on  the  nervous  system,  485. 

Galloway  (T.)  on  Femel's  measure  of  a 
degree,  22. 

Gardner  (Dr.  D.  P.)  on  the  influence  of 
the  dew-point  on  vegetables,  1. 

Gassiot  (J.  P.)  on  the  polarity  of  the  vol- 
taic battery,  485. 

Geological  Society,  proceedings  of  the, 
141,306,365,540. 

Geology : — on  the  position  of  the  Cornish 
killas  in  the  Devonian  system,  25  ;  on 
the  stratified  rocks  inferior  to  the  old 
red  sandstone,  141 ;  effects  produced 
by  the  ancient  glaciers  of  Caernarvon- 
shire, 180 ;  on  shells  and  corals  in  a 
conglomerate  at  Malvern,  288  ;  on  the 
geology  of  the  United  States,  and  on 
Stigmaria  clay,  306. 

Geometry,  analytic,  on  a  theorem  in,  176, 
444. 

,  the  difficulties  of  elementary, 

&c,  review  of  the,  405. 


INDEX. 


565 


Geometry,  spherical,  on  the  application 
of  analysis  to,  532. 

Gcrhardt  (M.)  on  quinoiline,  449. 

Glaciers,  on  the  effects  produced  by  the 
ancient,  180 ;  on  some  phenomena 
observed  on,  362. 

Glucinium  and  its  compounds,  researches 
on,  284. 

Gold,  use  of  the  chloride  of,  as  a  test  for 
vegetable  alkalies,  489. 

Goodwin  (H.  A.)  on  the  property  of  the 
parabola,  219. 

Graves  (Rev.  C.)  on  the  application  of 
analysis  to  spherical  geometry,  532. 

Greenovite,  description  of,  246. 

Grove  (W.  R.)  on  the  constant  voltaic 
battery,  333 ;  on  a  gaseous  voltaic 
battery,  417. 

Guano,  examination  of,  385. 

Gulliver  (G.)  on  the  nuclei  of  the  blood- 
corpuscles  of  the  Vertebrata,  107  ;  on 
the  structure  of  fibrine,  109 ;  on  the 
pus-like  globules  of  the  blood,  168, 
241 ;  on  the  structure  of  false  mem- 
branes, ib. 

Gymnotus  electricus,  remarks  on,  62, 
312. 

Hajmatoxylin,  examination  of,  446. 

Hall  (Capt.  Basil)  on  the  occultation  of 
Venus,  Sept.  11,  1841,  58. 

Halley's  comet,  observations  on,  397. 

Hansen  (Prof.),  award  of  the  astronomi- 
cal gold  medal  to,  521. 

Hare  (Dr.)  on  hyponitrite  of  metbyle, 
150 ;  on  the  electricity  of  steam,  151 ; 
on  hypochlorite  of  methyle,  152. 

Harris  (W.  S.)  on  the  action  of  lightning 
conductors,  313. 

Heat,  specific,  of  plants,  1. 

Henderson  (Prof.)  on  the  parallax  of  a 
Centauri,  531. 

Herschcl  (Sir  J.  F.  W.)  on  the  action  of 
the  rays  of  the  solar  spectrum  on  ve- 
getable colours,  225  ;  on  some  phaeno- 
mena  observed  on  glaciers,  and  on  the 
internal  temperature  of  masses  of  ice, 
362. 

Hertwig  (M.)  on  the  sulphates  of  alumina 
and  chromium,  281. 

Hess  (M.)  on  the  scientific  labours  of 
Richter,  81. 

Hippuric  acid,  on  the  preparation  of,  382. 

Hood  (Ch.)  on  changes  in  the  structure 
of  iron,  130. 

Hopkins  (W.)  on  the  elevation  and  de- 
nudation of  the  district  of  the  lakes  of 
Cumberland  and  Westmoreland,  468. 

Howard's  (Luke)  Cycle  of  18  Years,  re- 
viewed, 69. 

Hunt  (Mr.)  on  the  destruction  by  earth- 
quake of  the  town  of  Prava  de  Victoria, 
365. 


Hunt  (R.)  on  thermography,  and  on  the 
formation  of  images  in  the  dark,  462. 

Hutchinson  (J.)  on  the  specific  heat  and 
conducting  power  of  building  materials, 
318. 

Hydrobenzamide,  action  of  potash  on, 
18. 

Hydrogen,  bichloride  of,  320. 

Hyposulphites,  on  some  double,  20,  279. 

Ice,  on  the  boulders  transported  by,  180 ; 
on  the  internal  temperature  of  large 
masses  of,  362. 

Images,  on  the  formation  of,  in  the  dark, 
462. 

Indigo-nitric  acid,  experiments  on,  450. 

Influenza,  on  the  causes  of  the,  52. 

Institution  of  Civil  Engineers,  proceed- 
ings of  the,  401. 

Iodine,  detection  of,  in  bromides,  324 ; 
on  the  coloured  films  formed  by,  upon 
various  metals,  426. 

Iron,  on  changes  in  the  structure  of,  130. 

Ivory  (Mr.),  notice  of  the  late,  327. 

Jellett  (J.  H.)  on  surfaces  of  the  second 
order,  64. 

Kane  (Dr.  R.)  on  the  compounds  of  pal- 
ladium and  platinum,  50 ;  on  the  basic 
sulphate  of  mercury,  35. 

Kelland  (Rev.  P.)  on  the  theory  of  mole- 
cular action,  29,  124,  202,  263,  340, 
342,  344,  422,  437. 

Klett  (M.)  on  tachylite,  77. 

KobeU  (M.)  on  chlorite  and  repidolite,  76. 

Kopp  (Dr.)  on  some  chromates,  283. 

Langlois  (M.)  on  a  new  acid  of  sulphur, 
19. 

Larocque  (M.)  on  chloride  of  gold  as  a 
test  for  vegetable  alkalies,  489. 

Latitude  at  sea,  on  a  method  of  deter- 
mining, 531. 

Laurostearine  and  laurostearic  acid,  com- 
position of,  237. 

Lead,  action  of  water  on,  158. 

Lee's  (Dr.)  observatory  at  Hart  well,  on 
the  longitude  of,  56. 

Lee  (Dr.  R.)  on  the  nervous  ganglia  of 
the  uterus,  228. 

Lefroy  (Lieut.  J.  H.)  on  the  influence  of 
the  moon  on  the  atmospheric  pressure, 
227. 

Lenz  (M.)  on  some  hyposulphites,  20. 

Letheby  (H.)  on  the  anatomy  of  the 
Gymnotus  electricus,  312. 

Liebig  and  Wohler  (Prof.)  on  opianic 
acid,  449. 

Light,  on  the  theory  of  the  dispersion 
of,  122,  217,340,437;  on  the  absorp- 
tion of,  208. 

,  latent,  on  the  discovery  of,  348. 

Lightning  conductors,  observations  on, 
63,  310,  313. 

Litton  (Mr.)  on  a  new  salt  of  soda  and 


566 


INDEX. 


protoxide  of  platina,  413 ;  on  the 
plumbo-sulphate  of  ammonia,  452. 

Littrow  (Prof.),  notice  of  the  late,  510. 

Lloyd  (Prof.  H.)  on  a  remarkable  mag- 
netic disturbance  on  the  2nd  and  4th 
July  1842,  137. 

Logarithmic  and  trigonometric  tables, 
&c,  noticed,  406. 

London  Electrical  Society,  proceedings 
of  the,  61,310,  404,  484. 

Luminous  waves,  on  the  motion  of,  in  an 
elastic  medium,  46. 

Lyell  (C.)  on  the  geology  of  the  United 
States,  and  on  the  Stigmaria  clay, 
306 ;  on  the  recession  of  the  falls  of 
the  Niagara,  548. 

MacCullagh  (J.)  on  the  dynamical  theory 
of  crystalline  reflexion  and  refraction, 
228 ;  on  the  dispersion  of  the  optic 
axes,  and  of  the  axes  of  elasticity  in 
biaxal  crystals,  293 ;  on  the  law  of 
double  refraction,  407. 

Magnetic  disturbance,  notice  of  a  re- 
markable, 137. 

Magneto-electricity,  experiments  in,  33. 

Mallet  (R.)  on  the  physical  properties  of 
alloys  of  copper  with  tin  and  zinc,  66. 

Manzini  (M.)  on  cinchovatina,  323. 

Marchand  (M.)  on  indigotic  acid,  450. 

Marianini  (Prof.)  on  the  currents  pro- 
duced by  the  induction  of  electric  cur- 
rents, 497. 

Marsson  (M.)  on  laurostearine  and  lau- 
rostearic  acid,  237. 

Meitzendorff  (M.)  on  the  sulphocyanu- 
rets,  280. 

Membranes,  false,  on  the  structure  of, 
241. 

Menispermum  Cocculus,  chemical  exa- 
mination of  the  fruit  of,  161. 

Mercurial  compounds,  action  of  chlo- 
rides on,  320,  492. 

Mercury,  on  the  basic  sulphate  of,  35  ; 
on  the  change  of  colour  in  the  bini- 
odide  of,  192 ;  change  of  colour  of  the 
iodide,  336  ;  solubility  of  salts  in  per- 
nitrate  of,  237. 

Meteorological  observations  and  table, 
79,  80  ;  159, 160  ;  239,  240  ;  327,328; 
415,  416  ;  495,  496. 

Mialhe  (M.)  on  the  action  of  chlorides 
upon  protochloride  of  mercury,  320, 
492. 

Miller  (Prof.  W.  H.)  on  the  crystals  of 
the  red  oxalate  of  chromium  and  pot- 
ash, 201 ;  on  the  optical  constants  of 
tourmaline,  dioptase,  and  anatase,  277. 

Millon  (M.)  on  the  bichloride  of  hydro- 
gen, 320. 

Minerals,  analyses  of :— chlorite  and  repi- 
dolite,  76 ;  tachylite,  77 ;  of  native  aiu- 
minates,  78 ;  Greenovite,  246  ;  on  the 


salt  steppe  south  of  Orenburg,  357  ;  on 
phenomena  observed  on  glaciers,  362 ; 
of  the  Himalaya  mountains,  366  ;  ma- 
rine turtles  from  the  London  clay,  370; 
elevation  and  denudation  of  the  Lake 
district,  468 ;  bone-bed  in  the  lower 
lias  of  Tewkesbury,  540  ;  fossil  bones 
on  a  raised  beach  near  Plymouth,  543  ; 
production  of  faults  and  contortions  in 
strata,  544 ;  on  plants  in  the  plastic 
clay  of  the  Hampshire  coast,  546  ;  on 
the  mouths  of  Ammonites  and  on  fos- 
sils from  the  Oxford  clay,  ib. ;  reces- 
sion of  the  Falls  of  the  Niagara,  548  ; 
geology  of  the  South  of  Westmoreland, 
555. 

Molecular  action,  on  the  theory  of,  124, 
202,  263,  340,  342,  344,  422, 437. 

Molecules  of  bodies,  agency  of  caloric  in 
modifying  the  aggregations  of  the,  313. 

Molybdate  of  lead,  remarks  on  the,  73. 

Moon,  influence  of  the,  on  atmospheric 
pressure,  227. 

Moore  (Dr.)  on  fossil  bones  found  on  a 
raised  beach  near  Plymouth,  543. 

Mosander  (M.)  on  the  new  metal  didy- 
mium,  278. 

Moseley  (Rev.  H.)  on  conchyliometrv, 
300. 

Moser  (Prof.)  on  latent  light,  348,  409  ; 
on  the  recent  discoveries  of,  462. 

Motion,  on  fluid,  29 ;  of  luminous  waves 
in  an  elastic  medium,  46. 

M  tiller  (M.)  observations  of  Halley's  co- 
met in  the  years  1835,  1836,  397. 

Murchison  (R.  I.)  on  the  salt  steppe 
south  of  Orenburg,  and  on  a  remark- 
able freezing  cavern,  357. 

Muscle,  on  the  structure  of,  351. 

Nativelle  (M.)  on  the  preparation  of 
oxichloric  acid,  157. 

Nervous  system,  on  malformations  of  the, 
485. 

Newmann's  (F.  W.)  difficulties  of  ele- 
mentary geometry,  reviewed,  405. 

Niagara,  on  the  recession  of  the  falls  of 
the,  548. 

Nicotin,  constitution  of,  19. 

Nitrate  of  soda  for  constant  batteries,  61. 

Nitrates  and  chlorates,  method  of  distin- 
guishing between,  74. 

Nitrogen,  on  compounds  of,  with  boron 
and  silicon,  270. 

Nixon  (C.)  on  the  tunnels  between  Bris- 
tol and  Bath  on  the  Great  Western 
Railway,  401. 

Nuclei  of  the  blood-corpuscles  of  the 
vertebrata,  observations  on  the,  107. 

O'Brien  (Rev.  M.)  on  the  dispersion  of 
light,  342,  344. 

Oils  : — of  fennel,  anise,  and  star-anise,  15  ; 
action  of  chromic  acid  on  volatile,  1 7  ; 


INDEX. 


567 


of  turpentine,  formation  of  formic  acid 
in,  236. 

Opianic  acid,  preparation  of,  449. 

Optic  axes,  on  the  dispersion  of  the,  293. 

Optical  constants  of  tourmaline,  dioptase, 
and  anatase,  277. 

Ortigosa  (V.)  on  nicotin,  19 ;  on  the 
composition  of  conia,  414. 

Otto  (M.)  on  distinguishing  zinc  from 
manganese,  412. 

Owen  (Prof.  R.)  on  the  fossil  remains  of 
six  species  of  marine  turtles,  370. 

Oxichloric  acid,  on  the  preparation  of, 
157. 

Oxygen,  new  process  for  preparing,  42. 

Palladium  and  platinum,  on  the  com- 
pounds of,  50. 

Parabola,  on  a  property  of  the,  190,  219. 

Parnell  (E.  A.)  on  the  equilibrium  of  the 
temperature  of  bodies  in  contact,381. 

Pascal's  mystic  hexagram,  37. 

Pearce  (J.  C.)  on  the  mouths  of  ammo- 
nites, 546. 

Peligot  (M.)  on  the  compounds  of  sugar 
with  bases,  451. 

Pepsin,  on  the  composition  of,  491. 

Persoz  (M.)  on  the  action  of  chromic 
acid  on  volatile  oils,  17. 

Phillips  (J.)  on  shells  and  corals  in  aeon- 
glomerate  at  Malvern,  288. 

Phillips  (Mr.)  on  a  fatal  accident  by  light- 
ning, 404. 

Photography,  on  facts  connected  with, 
348,  409. 

Piesse  (S.)  observations  on  brewing,  317. 

Plants,  on  the  existence  of  sulphur  in, 
74 ;  action  of  salts  on,  76 ;  fossil, 
occurrence  of  in  the  plastic  clav, 
546. 

Plates,  on  the  colours  of  thin,  208. 

Porrett  (R.)  on  a  curious  formation  of 
Prussian  blue,  384. 

Posselt  (M.)  on  the  preparation  of  ferro- 
cyanic  acid,  325. 

Potash  and  chromium,  on  a  new  oxalate 
of,  197,  201. 

Powell  (Prof.  B.)  on  the  theory  of  the 
dispersion  of  light,  122,  217. 

Quina  and  cinchonia,  on  the  preparation 
of,  171. 

Quinoiline,  preparation  of,  449. 

Rammelsberg  (Dr.)  on  the  hvposulphites, 
279. 

Rees  (J.,  jun.)  on  general  formula  for 
eliminating  the  weights  of  mixed  bases, 
188. 

Refraction,  on  the  law  of  double,  407- 

Reizet  (M.)  on  the  determination  of  ni- 
trogen in  organic  analyses,  412. 

Repidolite,  analysis  of,  76.  , 

Richter  (J.  B.)  on  the  scientific  labours 
of,  81. 


Roberts  (M.)  on  a  new  form  of  battery, 

311. 
Rochleder  (M.)  on  the  action  of  hydrate 

of  potassa  on  hydrobenzamide,  18. 
Royal  Astronomical  Society,  proceedings 

of  the,  56,  397,  477,510;  anniversary 

of  the,  510. 
Royal  Irish  Academy,  proceedings  of  the, 

64,  228,  389,  532. 
Royal  Society,  proceedings  of  the,  50, 

220. 
Rose  (G.)  on  the  molybdate  of  lead,  73. 
Rose  (H.)  on  the  analysis  of  native  alu- 

minates,  78 ;  on  the  action  of  water 

on  sulphurets  and  haloid  salts,  285. 
Rothman  (R.  W.)  on  the  mass  of  Venus, 

529. 
Salt  steppe  south  of  Orenburg,  observa- 
tions on  the,  357. 
Santini  (M.)  on  Bremicker's  comet,  59  ; 

catalogue  of  1677  stars,  60. 
Schubert  (M.)  on  the  preparation  of  pure 

potash  and  soda,  324. 
Schulze  (M.)  on  a  new  method  of  ascer- 
taining the  quantity  of  phosphoric  acid, 

379. 
Schweitzer  (Dr.  E.  G.)  on  the  analysis  of 

the  chalk  of  the  Brighton  cliffs,  379. 
Sedgwick   (Rev.   A.)  on    the    stratified 

rocks  inferior  to  the  old  red  sandstone, 

141. 
Sharpe  (D.)  on  the  geology  of  the  south 

of  Westmoreland,  555. 
Sheepshanks  (Rev.  R.)  on  Mr.  Snow's 

observations   of  Venus  and  the  star 

A.  S.  C.  423,  398. 
Shells  in  a  conglomerate  at  Malvern,  288. 
Smee  (A.)  on  the  voltaic  circuit,  with 

formulae  for  ascertaining  its  power,  248. 
Solar  rays,  on  the  extinction  of  the,  223. 
Specific  heat  and  conducting  power  of 

building  materials,  318. 
Stars,   on   an  instrument  for  observing 

right  ascensions  and  declinations  of, 

477. 
Steam,  electricity  of  nascent,  151. 
Stearophanic  acid  and  salts,  composition 

of,  161. 
Stigmaria-clay  of  Pennsylvania,  306. 
Stokes  (G.  G.)  on  the  rectilinear  motion 

of  fluids,  297,  423. 
Strickland  (H.  E.)  on  the  occurrence  of 

the  Bristol  bone-bed  in  the  lower  lias 

near  Tewkesbury,  540. 
Sugar,  on  the  compounds  of,  with  bases, 

451. 
Sulphocyanurets,  on  the,  280. 
Sulphur,  on  a  new  acid  of,  19 ;  on  the  ex- 
istence of,  in  plants,  74. 
Surfaces,  on  some  new  properties  of,  64. 
Sylvester  (Prof.  J.  J.)  on  the  dialytic  me- 
thod of  elimination,  534. 


568 


INDEX. 


Tachylite,  analysis  of,  77. 

Talbot  (II.  F.)  on  the  iodide  of  raercurv, 
336. 

Temperature  of  vegetables,  1. 

Thibierge  (M.)  on  chloride  of  gold  as  a 
test  for  vegetable  alkalies,  489. 

Tithonicity,  a  new  imponderable  sub- 
stance, 453. 

Torsion-rod,  experiments  with  the,  111. 

Tourmaline,  on  the  optical  constants  of, 
277. 

Tubercles,  on  the  nature  of,  171. 

Turpeth  mineral,  on  the  composition  of, 
35. 

Turtles,  description  of  the  fossil  remains 
of  six  species  of,  370. 

Ultramarine,  on  the  blue  colour  of,  156. 

Uranite,  on  the  production  of  artificial, 
387. 

Uterus,  on  the  nervous  ganglia  of  the, 
228. 

Uvic  acid,  on  the  salts  of,  18. 

Vapour,  aqueous,  on  the  force  of,  389. 

Vegetables,  on  the  influence  of  the  dew- 
point  on,  1. 

Venus,  on  the  lunar  occultation  of,  Sept. 
11,  1841,58;  on  the  mass  of,  398, 529. 

Vogel  (M.  jun.)  on  a  method  of  distin- 
guishing between  nitrates  and  chlo- 
rates, 74 ;  on  curcumine,  233  ;  on  pep- 
sin, 491. 

(M.,  sen.)  on  the  existence  of  sul- 
phur in  plants,  74  ;  on  the  action  of 
salts  on  living  plants,  76. 

Voltaic  battery,  observations  on  the  con- 
stant, 329 ;  on  a  remarkable  new,  417; 
on  the  polarity  of  the,  485. 

circuit,  new  definition  of  the,  248. 

combinations,  observations  on,  54. 


Wackenroder  (II.)  on  the  solubility  of 
the  insoluble  salts  of  the  alkaline 
earths  in  hydrochlorate  of  ammonia 
and  chloride  of  sodium,  236 ;  on  the 
precipitation  of  certain  salts  by  excess 
of  acids,  ib. 

Walker  (C.  V.)  on  electrotype  manipula- 
tion, 61 ;  on  lightning  conductors,  63, 
310,  313. 

Wallace's  (Prof.)  property  of  the  para- 
bola, proof  of,  219. 

Waller  (Dr.  A.)  on  the  coloured  films 
formed  by  iodine,  bromine,  and  chlo- 
rine upon  various  metals,  426. 

Warington  (R.)  on  the  change  of  colour 
in  the  biniodide  of  mercury,  192 ;  on 
the  red  oxalate  of  chromium  and  pot- 
ash, 201 ;  on  a  new  chromate  of  man- 
ganese, 380. 

Water,  action  of,  on  lead,  158. 

Weppen  (M.)  on  the  production  of  formic 
acid  in  oil  of  turpentine,  236. 

Wettinger  (M.)  on  an  instrument  for  ob- 
serving right  ascensions  and  declina- 
tions of  stars,  477. 

Wiggers  (A.)  on  the  presence  of  anti- 
mony in  arsenious  acid,  238. 

Williams  (Rev.  D.)  on  the  true  position 
in  the  Devonian  system  of  the  Cornish 
killas,  25. 

Wind,  effect  of  the  direction  of  the,  on 
the  difference  between  distant  baro- 
meters, 222. 

Wbhler  (Prof.)  on  opianic  acid,  449. 

Yeast,  on  the  preparation  of  artificial, 
352. 

Yorke  (Lieut.-Col.  P.)  on  the  effect  of  the 
direction  of  the  wind  on  the  difference 
between  distant  barometers,  222. 


END  OF  TH 


VOLUME. 


PRINTED  BY  RICHARD  AND  JOHN  E.  TAYLOR, 
RED  HON  COURT,  FLEET  STREET. 


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